Aspek Penerangan, Kebisingan dan Getaran di Tempat Kerja dan Pengendaliannya

PENERANGAN

Penerangan di tempat kerja adalah salah satu sumber cahaya yang menerangi benda-benda ditempat kerja. Penerangan dapat berasal dari cahaya alami dan cahaya buatan, banyak obyek kerja beserta benda atau alat dan kondisi disekitar yang perlu dilihat oleh tenaga kerja, hal ini penting untuk menghindari kecelakaan yang mungkin terjadi, selain itu penerangan yang memadai memberikan kesan pemandangan yang lebih baik dan keadaan lingkungan yang menyegarkan.

Alat untuk mengetahui intensitas penerangan adalah “Luxmeter”. Alat ini bekerja berdasarkan pengubahan energy cahaya menjadi tenaga listrik oleh photo electric cell. Intensitas penerangan diukur oleh 2 cara, yaitu:

• Penerangan umum, diukur setiap meter persegi luas lantai, dengan tinggi pengukuran kurang lebih 85 cm dari lantai (setinggi pinggang).
• Penerangan lokal, diukur di tempat atau meja kerja pada obyek yang dilihat oleh tenaga kerja.

Penerangan yang buruk di lingkungan kerja akan menyebabkan hal-hal sebagai berikut :

• Kelelahan dan ketidaknyamanan pada mata yang akan mengakibatkan kurangnya daya efesiensi kerja.
• Kelelahan mental yang akan berpengaruh pada kelelahan fisik.
• Keluhan pegal di daerah mata dan sakit kepala di sekitar mata.
• Kerusakan alat penglihatan (mata).
• Meningkatnya kecelakaan kerja.

Pengendalian terhadap penerangan buruk dapat dilakukan dengan cara :

Pengendalian secara teknis

           Memperbesar ukuran obyek (sudut penglihatan) dengan menggunakan kaca pembesar dan kaca pembesar dan layer monitor, memperbesar intensitas penerangan, menambah waktu yang diperlukan untuk melihat obyek, bila menggunakan penerangan alami, harus diperhatikan agar jalan masuknya sinar tidak terhalang.

Pengendalian secara administrative

Untuk pekerjaan malam atau yang membutuhkan ketelitian tinggi, memperkerjakan tenaga kerja yang berusia relatif masih muda dan tidak menggunakan kacamata adalah lebih baik.

Menjaga kebersihan dinding, langit-langit, lampu dan perangkatnya penting untuk diperhatikan. Perawatan tersebut sebaiknya dilakukan minimal 2 kali dalam 1 tahun, karena kotoran atau debu yang ada ternyata dapat mengurangi intensitas penerangan.

KEBISINGAN

            Bising adalah suara/bunyi yang tidak diinginkan. Terdapat dua hal yang menentukan kualitas suatu bunyi, yaitu frekuensi dan intensitasnya. Frekuensi dinyatakan dalam jumlah getaran perdetik (Hertz, Hz), telinga manusia mampu mendengarkan frekuensi antara 16-20.000 Hz. Intensitas atau arus energy persatuan luas biasanya dinyatakan dalam suatu logaritma yang disebut desible (dBA atau dB(A)). Alat pengukur kebisingan disebut level meter. Contoh di pabrik yaitu generator pembangkit listrik, pemotong plat baja, pekerjaan bubut, gurinda, pengamplasan bahan logam. Intensitas kebisingan yang dianjurkan adalah 85 dB(A) untuk 8 jam kerja.

Kebisingan di lingkungan kerja akan menyebabkan hal-hal sebagai berikut :

• Mengurangi kenyamanan dalam bekerja
• Mengganggu komunikasi/percakapan antar pekerja
• Mengurangi konsentrasi
• Menurunkan daya dengar
• Tuli akibat kebisingan

Pengendalian terhadap kebisingan dapat dilakukan dengan cara :

Pengendalian secara teknis

Pengendalian secara teknis dapat dilakukan pada sumber bising, media yang dilalui bising dan jarak sumber bising terhadap pekerja. Pengendalian bising pada sumbernya merupakan pengendalian yang sangat efektif dan hendaknya dilakukan pada sumber bising yang paling tinggi.

Cara-cara yang dapat dilakukan antara lain :

• Desain ulang peralatan untuk mengurangi kecepatan atau bagian yang bergerak, menambah muffler pada masukan maupun keluaran suatu buangan, mengganti alat yang telah usang dengan yang lebih baru dan desain peralatan yang lebih baik.
• Melakukan perbaikan dan perawatan dengan mengganti bagian yang bersuara dan melumasi semua bagian yang bergerak.
• Mengisolasi peralatan dengan cara menjauhkan sumber dari pekerja/penerima, menutup mesin ataupun membuat barrier/penghalang.
• Meredam sumber bising dengan jalan memberi bantalan karet untuk mengurangi getaran peralatan dari logam, mengurangi jatuhnya sesuatu benda dari atas ke dalam bak maupun pada sabuk roda.
• Menambah sekat dengan bahan yang dapat menyerap bising pada ruang kerja. Pemasangan peredam ini dapat dilakukan pada dinding suatu ruangan bising.

Pengendalian secara administratif

Pengendalian ini meliputi rotasi kerja pada pekerja yang terpapar oleh kebisingan dengan intensitas tinggi ke tempat atau bagian lain yang lebih rendah, cara mengurangi paparan bising dan melindungi pendengaran.

• Pemakaian alat pelindung telinga. Pengendalian ini tergantung terhadap pemilihan peralatan yang tepat untuk tingkat kebisingan tertentu, kelayakan dan cara merawat peralatan. Dapat menggunakan sumbat telinga (ear plug) atau tutup telinga (ear muff).
• Pengendalian secara medis. Pemeriksaan audiometri secara periodik.

GETARAN

Getaran adalah suatu factor fisik yang bekerja pada manusia dengan penjalaran (Transmission) dari pada tenaga mekanik yang berasal dari sumber goyangan (osilattor). Getaran kerja adalah getaran mekanis yang ada ditempat kerja dan berpengaruh terhadap tenaga kerja.

Getaran dihasilkan oleh; Mesin-mesin diesel, mesin produksi, kendaraan-kendaraan, Tractor, truk, bus, tank dll, alat-alat kerja tangan (hand tool) dengan menggunakan mesin: jack hammer (pembuka jalan), pneumatic hammer (pabrik besi), jack lec drill (pengebor batu gunung, karang dll).

Jenis-jenis getaran kerja :

        1. Getaran seluruh badan  (Whole body vibration)

Getaran ini berpengaruh terhadap seluruh tubuh, dihantarkan melalui bagian tubuh tenaga kerja yang menopang seluruh tubuh. Misalnya : kaki saat berdiri, pantat pada saat duduk, punggung  saat bersandar, lengan saat bersandar. Getaran ini mempunyai frekwensi 5 – 20 Hz.

        2. Getaran alat-lengan (Hand arm vibration)

Getaran yang merambat melalui tangan atau lengan dari operator atal yang bergetar. Getaran ini mempunyai frekuensi 20 – 500 Hz.

Getaran di lingkungan kerja akan menyebabkan hal-hal sebagai berikut :

Pengaruh whole body vibration

• Penglihatan kabur
• Sakit kepala
• Sakit pada persendian dan otot
• Gemeteran (shakeness)
• Kerusakan organ tubuh bagian dalam

Pengaruh hand and arm vibration

• Sakit kepala
• Sakit pada persendian dan otot lengan
• Indera perasa pada jari-jari menurun fungsinya
• Terbentuk noda putih pada punggung jari / telapak tangan (white finger syndrome)

Pengendalian terhadap getaran dapat dilakukan dengan cara :

Pengendalian secara teknis

• Menggunakan peralatan dengan intensitas getaran yang rendah (dilengkapi dengan peredam)
• Menyisipkan damping / peredam diantara tangan dan alat
• Penempatan alat yang bergetar dengan baik
• Perawatan mesin atau alat kerja dengan baik
• Menggunakan remote kontrol

Pengendalian secara administrative

• Rotasi pekerja
• Mengurangi jam kerja sehingga sesuai NAB yang berlaku
• Secara medis yaitu pemeriksaan berkala sesuai keperluan
• Penggunaan APD

Higiene Perusahaan

Higiene Perusahaan adalah spesialisasi dalam ilmu higiene beserta prakteknya yang dengan mengadakan penilaian kepada faktor-faktor penyebab penyakit kualitatif dan kuantitatif dalam lingkungan kerja dan perusahaan melalui pengukuran yang hasilnya dipergunakan untuk dasar tindakan korektif kepada lingkungan tersebut serta bila perlu pencegahan, agar pekerja dan masyarakat sekitar suatu perusahaan terhindar dari bahaya akibat kerja serta dimungkinkan mengecap derajat kesehatan setinggi-tingginya. (Menurut Suma’mur, 1976). Jenis sifat-sifat Higiene Perusahaan; sasaran adalah lingkungan kerja dan bersifat teknik.

Kesehatan kerja adalah spesialisasi dalam ilmu kesehatan/kedokteran beserta prakteknya yang bertujuan, agar pekerja/masyarakat memperoleh derajat kesehatan setingg-tingginya, baik fisik, atau mental, maupun sosial, dengan usaha-usaha preventif dan kuratif, terhadap penyakit-penyakit/gangguan-gangguan kesehatan yang diakibatkan faktor-faktor pekerjaan dan lingkungan kerja, serta terhadap penyakit-penyakit umum. Jenis sifat-sifat kesehatan kerja yaitu; sasaran adalah manusia dan bersifat medis.

Kesehatan lingkungan kerja yang sering kali dikenal juga dengan istilah Higiene Industri atau Higiene Perusahaan. Tujuan utama dari Higiene Perusahan dan Kesehatan Kerja adalah menciptakan tenaga kerja yang sehat dan produktif. Selain itu Kegiatannya bertujuan agar tenaga kerja terlindung dari berbagai macam resiko akibat lingkungan kerja, masyarakat sekitar perusahaan dan masyarakat umum yang menjadi konsumen dari hasil-hasil produksi perusahaan, diantaranya melalui pengenalan, evaluasi, pengendalian dan melakukan tindakan perbaikan yang mungkin dapat dilakukan. Sehingga dibutuhkan pemahaman mengenai hygiene perusahaan dan kesehatan kerja.

Tujuan utama dari Higene Perusahaan dan Kesehatan Kerja adalah menciptakan tenaga kerja yang sehat dan produktif. Tujuan demikian mungkin dicapai, oleh karena terdapatnya korelasi diantara derajat kesehatan yang tinggi dengan produktivitas kerja atau perusahaan, yang didasarkan kenyataan-kenyataan sebagai berikut :

1. Untuk efisiensi kerja yang optimal dan sebaik-baiknya. Pekerjaan harus dilakukan dengan cara dan dalam lingkungan kerja yang memenuhi syarat-syarat kesehatan. Lingkungan dengan cara yang dimaksud meliputi diantaranya : tekanan panas, penerangan ditempat kerja, debu di udara ruang kerja, sikap badan, perserasian manusia dan mesin, pengekonomisan upaya. Cara dan lingkungan tersebut perlu disesuaikan pula dengan tingkat kesehatan dan keadaan gizi tenaga kerja yang bersangkutan.
2. Biaya dari kecelakaan dan penyakit akibat kerja, serta penyakit umum yang meningkat jumlahnya oleh karena pengaruh yang memburukkan keadaan oleh bahaya-bahaya yang ditimbulkan oleh pekerjaan adalah sangat mahal dibandingkan dengan biaya untuk pencegahannya. Biaya-biaya kuratif yang mahal seperti itu meliputi : pengobatan, peralatan rumah sakit, rehabilitasi, absenteisme, kerusakan mesin, peralatan dan bahan oleh karna kecelakaan, terganggunya pekerjaan, dan cacat yang menetap.

PRINSIP HIGIENE PERUSAHAAN

Untuk penerapan higiene perusahaan di tempat kerja suatu perusahaan akan di perlukan pemahaman terhadap tiga prinsip dasar yaitu :

1. Pengenalan terhadap bahaya faktor-faktor lingkungan kerja.

Pengenalan dalam prinsip dasar penerapan Higiene Industri/perusahaan yang pertama adalah pengenalan terhadap bahaya faktor – faktor yang timbul di lingkungan kerja sebagai akibat penerapan teknologi proses produksi suatu industri (yang meliputi faktor kimia, faktor fisik, faktor ergonomik dan faktor biologi) yang dapat berpengaruh buruk kepada pekerjaan dan lingkungan kerja, yang terhadap tenaga kerja dapat mengakibatkan gangguan kesehatan (sakit) yang akan mencakup pengetahuan dan pengertian tentang berbagai jenis bahaya serta pengaruhnya terhadap kesehatan tenaga kerja atau akibat – akibat yang dapat ditmbulkan kepada kesehatan tenaga kerja.

Mengenal atau rekognisi merupakan serangkaian kegiatan untuk mengenali suatu bahaya lebih detil dan lebih komprehensif dengan menggunakan suatu metode yang sistematis sehingga dihasilkan suatu hasil yang objektif dan bisa dipertanggungjawabkan. Dimana dalam rekognisi ini kita melakukan pengenalan dan pengukuran untuk mendapatkan informasi tentang konsentrasi, dosis, ukuran (partikel), jenis, kandungan atau struktur, dan sifat. Adapun tujuan dari pengenalan, yaitu :

• Mengetahui karakteristik suatu bahaya secara detil (sifat, kandungan, efek, severity, pola pajanan, besaran).
• Mengetahui sumber bahaya dan area yang  berisiko.
• Mengetahui pekerja yang berisiko.

2. Penilaian/evaluasi terhadap bahaya faktor-faktor lingkungan kerja.

Di dalam higiene industry/perusahaan evaluasi adalah proses pengambilan keputusan untuk menilai tingkat resiko pajanan dari bahaya semua faktor yang timbul (yang ada) di lingkungan tempat kerja kepada tenaga kerja, sebagai akibat penerapan teknologi proses produksi suatu industry ( termasuk faktor kimia, faktor fisik, faktor ergonomic, dan faktor biologi ).

Kebutuhan untuk melakukan evaluasi terhadap bahaya tersebut didorong oleh suatu kenyataan bahwa faktor yang timbul dilingkungan tempat kerja dapat menyebabkan sakit, lika, cacatdan kematian yang lebih cepat kepada tenaga kerja yag terpajan kepadanya. Maka dengan evaluasi telah diperoleh suatu manfaat yang berupa keinginan melakukan upaya pencegahan terhadap pajanan faktor – faktor lingkungan kerja yang berbahaya yang dapat menghasilkan pengaruh yang merugikan keehatan.

Pada tahap penilaian/evaluasi lingkungan, dilakukan pengukuran, pengambilan sampel dan analisis di laboratorium. Melalui penilaian lingkungan dapat ditentukan kondisi lingkungan kerja secara kuantitatif dan terinci, serta membandingkan hasil pengukuran dan standar yang berlaku, sehingga dapat ditentukan perlu atau tidaknya teknologi pengendalian, ada atau tidaknya korelasi kasus kecelakaan dan penyakit akibat kerja dengan lingkungannya , serta sekaligus merupakan dokumen data di tempat kerja. Tujuan dari pengukuran dalam evaluasi, yaitu :

• Untuk mengetahui tingkat risiko.
• Untuk mengetahui pajanan pada pekerja.
• Untuk memenuhi peraturan (legal aspek).
• Untuk mengevaluasi program pengendalian yang sudah dilaksanakan.
• Untuk memastikan apakah suatu area aman untuk dimasuki pekerja.
• Mengetahui jenis dan besaran hazard secara lebih spesifik.

3. Pengendalian terhadap bahaya faktor-faktor lingkungan kerja.

Pengendalian faktor – faktor lingkungan kerja sesungguhnya dimaksudkan untuk menciptakan atau memelihara lingkungan kerja agar tetap sehat dan aman atau memenuhi persyaratan kesehatan dan norma keselamatan, sehingga tenaga kerja terbebas dari ancaman gangguan kesehatan dan keamanan atau tenaga kerja tidak menderita penyakit akibat kerja dan tidak mendapat kecelakaan kerja.

Pengendalian faktor – faktor lingkungan kerja sesungguhnya dimaksudkan untuk menciptakan atau memelihara lingkungan kerja agar tetap sehat dan aman atau memenuhi persyaratan kesehatan dan norma keselamatan, sehingga tenaga kerja terbebas dari ancaman gangguan kesehatan dan keamanan atau tenaga kerja tidak menderita penyakit akibat kerja dan tidak mendapat kecelakaan kerja. Ada beberapa bentuk pengendalian atau pengontrolan di tempat kerja yang dapat dilakukan , yaitu :

• Eliminasi : Merupakan upaya menghilangkan bahaya dari sumbernya serta menghentikan semua kegiatan pekerja di daerah yang berpotensi bahaya.
• Substitusi : Modifikasi proses untuk mengurangi penyebaran debu atau asap, dan mengurangi bahaya, pengendalian bahaya kesehatan kerja dengan mengubah        beberapa peralatan proses untuk mengurangi bahaya, mengubah kondisi fisik bahan baku yang diterima untuk diproses lebih lanjut agar dapat menghilangkan potensi bahayanya.
• Isolasi : Menghapus sumber paparan bahaya dari lingkungan pekerja dengan menempatkannya di tempat lain atau menjauhkan lokasi kerja yang berbahaya dari pekerja lainnya, dan sentralisasi kontrol kamar.
• Engineering control : Pengendalian bahaya dengan melakukan modifikasi pada faktor lingkungan kerja selain pekerja.
• Administrasi control: Pengendalian bahaya dengan melakukan modifikasi pada interaksi pekerja dengan lingkungan kerja.
• APD (Alat Pelindung Diri) : Langkah terakhir dari hirarki pengendalian.
• Ventilasi umum : Mengalirkan udara bersih, aman, dan untuk menekan kadar kontaminan dari bahan yang berbahaya.
• Ventilasi lokal : Menangkap bahan kontaminan sebelum membahayakan pekerja.

PENGUJIAN LINGKUNGAN KERJA

            Proses pengujian lingkungan kerja yang dilakukan oleh seorang ahli hygiene perusahaan terutama ditujukan kepada faktor fisika, seperti suhu/tekanan panas, kelembaban, pencahayaan, kebisingan, getaran, radiasi, dan faktor kimia berupa gas, uap, larutan kimia, debu. Akan tetapi bersamaan dengan keahlian lain seperti ahli biologi, ahli ergonomi, psikolog, ahli lingkungan.

Pengujian lingkungan kerja dilakukan atas inisiatif pejabat yang berwenang untuk menentukan sejauh mana pekerja terpajan oleh faktor lingkungan kerja, menentukan efektivitas alat pengendali di perusahaan, meneliti tempat kerja berdasarkan keluhan atau gangguan kesehatan pekerja, peningkatan kesehatan pekerja dan produktivitas pekerja dan memenuhi komitmen perusahaan dalam penerapan Hiperkes dan Keselamatan Kerja dalam sistem manajemen nasional dan internasional. Terdapat juga NAB yang ditentukan sebagai pengendali. Nilai ambang batas (NAB) adalah sebagai pedoman dalam pengendalian bahaya lingkungan kerja.

Milestone of Development

THE FIRST YEAR

Motor Development

During early childhood, the primitive reflexes are replaced by voluntary motor control, which is under the higher cortical control. Motor development is a cumulative process; higher level skills are dependent on lower level skills.

           In the first two months, an infant’s movements consist largely of uncontrolled writhing with apparently purposeless hand opening and closing. Smiling occurs involuntarily. However, eye gaze, head turning, and sucking are under conscious control.

        At 2 to 6 month old, early reflexes that limited voluntary movement. Infants can begin to examine objects in the midline and manipulate them with both hands. Waning of early grasping reflex allows them to voluntarily hold and release objects. A novel object may elicit purposeful but inefficient reaching. The quality of spontaneous movements also changes, from larger writhing to smaller, circular movements, described as ‘fidgety’. Intentional rolling is made possible by increased control of truncal flexion. Head control improves, allowing infants to gaze across things and begin to take food from a spoon.

            Between 6 to 12 month old, infants gain the ability to sit up unsupported and later pivot while sitting, providing increasing opportunities to manipulate several objects at one time. These explorations are aided by the emergence of pincer grasp. Many infants begin crawling and pulling to stand around 8 months, and walk before 12 months.

Cognitive Development

            Caretaking activities provide visual, tactile, olfactory, and auditory stimuli. All these stimuli play an important part in the development of cognition. Infants can see, hear and smell within days of birth. They are able to perceive objects and events as coherent. These abilities allow them to sort stimuli into meaningful sets. Infants appear to seek stimuli actively as tough satisfying an innate need to make sense of the world.

            At the age 1 month, infants can enjoy conversations. By 5 to 6 weeks, infants begin to smile, at first once or twice in a day, more frequently and to more different stimuli as they get older. In a further week or two, they vocalize their pleasure when spoken to.

            Around 4 month old, infants are described as ‘hatching’ socially, they become interested in a wider world. Infants between 2 to 6 months old also explore their own bodies, staring intently at their hands, vocalizing, etc. These explorations represent early stage in the understanding of cause and effects as infants learn that voluntary muscle movements produce predictable tactile and visual sensation. They also have a role in the emergence of a sense of self.

            At 6 to 12 month old, infants begin to put everything into the mouth, later they are picked up, inspected, passed from hand to hand, and banged dropped, then mouthed. Each action represents a nonverbal idea about what things are for. Anytime after 5 months old, infants may begin to imitate such acts as chewing or protrusion of the tongue. From age 6 month, they begin to show memory of foodstuffs by strong reactions of like and dislike.

The major milestone is the achievement of object constancy (about 9 month), the understanding that objects continue to exist even when not seen. At 4 to 7 month, infants try to look for dropped toy, but quickly give up if it is not seen. With object constancy, infants persist in searching and finding hidden objects.

Emotional and Communication Development

Basic trust develops as infants learn that their urgent needs are met regularly. The consistent availability of a trusted adult creates a condition for secure attachment. The emotional significance of any experience depends on an individual child’s temperament as well as the parents’ responses.

At 2 to 4 month old, infants interact with increasing sophistication and range of emotions. The primary emotions of anger, joy, interest, fear, disgust and surprise appear in appropriate contexts as distinct facial expressions. Face-to-face with a trusted adult, the infant and adult match affective expressions. Such face-to-face behavior reveals the infant’s ability to share emotional states, the first step in the development of communication.

Between 6 to 12 months, infants can recognize parents and strangers, they may cling or cry anxiously when being approached by strangers. Separation often becomes more difficult. At the same time, the demand for autonomy emerges. Infants begin to refuse or consent activities. They may turn away as the spoon approaches when being fed, or may insist on holding it themselves. Self feeding with finger foods may be the only way to get them to eat. Tantrums make their first appearance as the drives for autonomy and mastery come in conflict with parental controls and with infants’ self limited abilities.

The average infants begin to vocalize with vowel sounds, ah, eh, uh, a week or two after beginning to smile in response to parents. In three or four weeks, these vowel sounds are followed by the addition of front consonant (m, p, b) and back consonant (g, k). At 2 to 3 months, he says “gaga.” At 3 months, infants hold long conversation with parents, with increasing tone and pitch. At 4 months, he says “ah goo”, and much vocal play begins, he enjoys the vibration when he razzes. At 6 months, they add many syllables, and by 7 months they begin combining syllables without meaning. Up to this stage, an infant’s vocalization is largely unrelated to his race or hearing.

Infants at 7 month are adept at nonverbal communication, expressing a range of emotions and responding to vocal tone and facial expressions. Around 9 months, infants become aware that emotions can be shared between people. Between 8 to 10 months, babbling takes on a new complexity, with many syllables (ba-da-ma) and inflections that mimic the native language. The first true word, that is a sound used consistently to refer to a specific object or person, appears in concert with the discovery of object constancy.

THE SECOND YEAR

Motor Development

            Most children begin to walk independently near their first birthday, some do not walk until 15 months. After several months of practice, the child is able to stop, pivot, and stoop without toppling over. At the age of 18-24 months, motor development is incremental, with improvement of the balance and agility and the emergence of running and stair climbing.

Cognitive Development

            Object exploration accelerates because reaching, grasping, and releasing are nearly fully mature and walking increases access to interesting things; Toddlers combine objects to create interesting effects such as stacking blocks. Playthings are more intended to be used for their intended purposes (comb for hair, cups for drinking). Imitation of parents and older children is an important mode of learning.

            At approximately 18 months, object permanence is firmly established. Cause and effect are better understood, and they demonstrate the flexibility in problem solving, using sticks to obtain a toy out of reach and figuring how to wind a mechanical toy.

Emotional Development

            Infants developmentally approaching the milestone of their first steps may be irritable. Once they start walking, their predominant mood changes markedly. Toddlers are described ‘intoxicated’ with their new ability and with the power to control the distance between themselves and their parents.

            In many children, the relative independence of the preceding period gives way to increased clinginess around 18 months. This stage, described as rapprochement, may be a reaction to growing awareness of the possibility of separation. Many children use a special blanket or stuffed toy as a transitional object: something that functions as a symbol of the absent parent.

            Self-conscious awareness and internalized standard of evaluation first appear at 18 to 24 months. They begin to reach for their own face, rather than the mirror image, when they see an unusual appearance. They begin to recognize a broken toy and may hand them to parents to fix. When tempted to touch a forbidden object, they may tell themselves “no, no,” evidence of internalization of standards of behavior.

Linguistic Development

            Receptive language proceeds expressive. By the time infants speak their first words, around 12 months, they already responds appropriately to several simple statements such as “no,” “bye-bye,” “give me.” By 15 months, the average child points to major body parts and uses four to six words spontaneously and correctly. Most communications of wants and ideas continues to be nonverbal.

            Labeling objects coincides with the advent of symbolic thought. Children may point at things with index finger and ask their names. After the realization that words can stand for things, a child’s vocabulary grows from 10-15 words at 18 months into 100 or more at 2 years. After acquiring about 50 words, toddlers begin to combine words to make simple sentences. At this stage, toddlers understand two-step commands, such as “give me the ball and then get your shoes.”

PRESCHOOL YEARS

Motor Development

            Most children walk with mature gait and run steadily before the end of their third year. Beyond this basic level, there is wide variation in ability as the range of motor activities expands to include throwing, catching, and kicking ball, climbing, dancing and other complex-pattern behaviors.

            Handedness is usually established by the third year. Variations in fine motor development reflect both individual proclivities and different opportunities for learning.

            Bowel and bladder control emerge during this period. Daytime bladder control typically precedes bowel control and girls precede boys. Bed-wetting is normal up to age 4 in girls and 5 in boys. Many children master toileting with ease, particularly once they are able to verbalize their bodily needs.

Cognitive Development

            The preschool period is characterized by magical thinking, egocentrism, and thinking that is dominated by perception. Magical thinking includes a confusion of coincidence for causality, animism, and unrealistic beliefs about the power of wishes.

            During the preschool period, play is marked by increasing complexity and imagination, from simple scripts replicating common experiences such as shopping (age 2-3 year) to a more extended scenarios involving singular events such as going to the zoo (age 3 or 4 year) to creation of scenario that have only been imagined, such as flying to the moon (age 4 or 5 year). Similar progression in socialization moves from minimal social interaction with peers during play (solo or parallel play, age 1 or 2 year) to cooperative play (age 3 or 4 year) to organized group play with distinct role assignments.

            Moral thinking mirrors and is constrained by a child’s cognitive level. Emphatic responses to others’ distress arise during the second year, but the ability to cognitively consider another child’s point of view remains limited through out the preschool period. Fairness is taken to mean equal treatment regardless of circumstantial differences. Rules tend to be absolute, with guilt assigned for bad outcomes regardless of intentions.

Emotional Development

Emotional challenges facing preschool children include accepting limits while maintaining a sense of self-direction, reigning in aggressive and sexual impulses, and interacting with a widening circle of adults and peers. At age 2 year, behavioral limits are predominantly external; the age 5 years, these controls need to be internalized if the child is to function in a typical classroom.

Children learn what behaviors are acceptable by testing limits. Excessively tight limits can undermine a child’s sense of initiative; whereas the overly loose limits can provoke anxiety in a child who feels no one is in control. Control is the central issue. Inability to control some aspects of the external world often results in a loss of internal control that is a temper tantrum. Tantrums normally appear toward the end of the first year of life, and peak in prevalence between 2 and 4 years.

Preschool children normally experienced complicated feelings toward their parents: intense love and jealousy and resentment and fear that angry feelings might lead to abandonment. The swirl of these emotions, most beyond the child’s ability to express or analyze, often find expression in highly labile moods.

Curiosity about genitals and adult sexual organs is normal. Modesty appears gradually between age 4 and 6 year, with wide variations among cultures and families.

Language Development

            Language development occurs most rapidly between 2 and 5 year of age. Vocabulary increases from 50-100 words to more than 2000. Sentence structures advances from telegraphic phrase to sentences incorporating all the major grammatical components. As a rule of thumb, between age 2 to 5, the number of words in typical sentences equals the child’s age (2 by age of 2, 3 by age of 3, and so on). By 2 ½, most children are using possessives (my ball), questions and negatives. By the 4, they can count to 4.

Developmental Brain Anomalies

Although the incidence of nervous system malformations in living newborns is 1%-3%, such malformations are present in 40% of infant deaths. The etiologies associated with developmental anomalies may result from a variety of insults from genetic to environmental. Abnormalities associated with the neural tube and the neural plate generally occur within the first 28 days of gestation. On the other hand, abnormalities associated with cellular proliferation and migration in the CNS generally occur after the 28th day of gestation. This chapter will cover malformations associated with both of these periods. Included among these malformations are Arnold-Chiari malformations and a group of disorders collectively referred to as neuronal migration defects (1).

Professor Hans Chiari, a German pathologist described a group of malformations characterized by the displacement of the cerebellum. He classified the manifestations into types based on the order of increasing severity (type I being least severe) and these became known as Chiari malformations (2). Of note, type II Chiari malformations (CM) are also known as the Arnold-Chiari malformation. However, other publications use "Arnold Chiari" malformations as the umbrella term for the four types of cerebellar displacement. This chapter will look at the Chiari malformations that are more commonly seen (1,3).

Type I CM is defined as a caudal displacement of the cerebellar tonsils below the foramen magnum by 5 mm. Hydrocephalus is present in 90% of patients and syringomyelia may also be present. Patients may live asymptomatically up until the third or fourth decade of life or later, when signs and symptoms of this disorder may present. The presentation is dependent upon the degree of the abnormality and associated manifestations, on neural structures. These can include lower cranial neuropathies, downbeat nystagmus, ataxia, vertigo, vocal cord paralysis, and eye movement abnormalities (3). Additional skeletal anomalies include scoliosis (especially from syringomyelia) and skull base abnormalities (2). The differential diagnosis of type I can vary tremendously, depending on the neural structures involved. A diagnosis of type I can be made on the basis of imaging (MRI is preferred) along with clinical information. Treatment is done surgically by cervical bony decompression of structures in the foramen magnum and along the spinal cord if necessary. This process involves removal of bone (usually by cutting through bones of the spine). Relief of signs and symptoms related to the compression of the brain stem is better than those related to the spinal cord (2). Treatment of hydrocephalus involves finding an alternative route of drainage of the cerebrospinal fluid in the ventricles. This is usually accomplished by a ventriculoperitoneal shunt (4). Successful interventions may allow the individual to have normal mental development, if there are no additional CNS malformations (2).

Type II (Arnold-Chiari) malformation is the commonest type of CM malformation (4). It is manifested by an increased caudal displacement of the cerebellum into the foramen magnum, along with the lower brainstem. Myelomeningocele is usually associated with this type II malformation usually resulting in hydrocephalus (80% or more). There is an increased likelihood to develop hydrocephalus if the meningomyelocele is more rostral. As in type I, the presentation of signs and symptoms depends upon the degree of the abnormality and associated manifestations, on neural structures. Symptoms related to hindbrain dysfunction may develop which include difficulty feeding, choking, stridor, apnea, vocal cord paralysis, pooling of secretion, and spasticity of the upper extremities. An increased head circumference may be present due to hydrocephalus. Ventricular enlargement may be slow or rapid and cause a bulging anterior fontanel, dilation of scalp veins, irritability, and vomiting. Diagnosis is the same as type I but a more severe displacement is seen, and a myelomeningocele is usually obvious on gross inspection. Treatment is done surgically to repair the myelomeningocele and to relieve the hydrocephalus. Bony decompression may also be performed. Prognosis depends on the site and severity of myelomeningocele. Improved prognosis is associated with a more caudal lesion. It is also advisable to recommend a multivitamin with folate for expectant mothers to reduce the risk of subsequent neural tube defects (3).

Type III (rare) CM is characterized by a cerebellar displacement into an occipital encephalocele. An occipital encephalocele is a defect in the closure of the neural tube near the base of the skull, a condition known as occipital encephalocele. Prognosis is poor (4).

Neuronal migration defects form a group of developmental brain anomalies. Abnormal cerebral cortical development is generally viewed as an improper migration of neural tissue. In other words, neurons fail to reach their destination in the cortex in the period of cortical neurogenesis beginning around 10 to 12 weeks of gestational age or earlier. Environmental factors such as retinoic acid, radiation, and methylmercury have been implicated in the pathogenesis. Viral infections in utero are also known to result in migrational abnormalities, although the mechanism of action is unknown. The abnormalities, which may present together, can be grouped into three general categories. They include lissencephaly/pachygyria, polymicrogyria, and heterotopia.

It is thought that lissencephaly and pachygyria are different representations of the same manifestation. Lissencephaly (means smooth brain) refers to a more diffuse bilateral brain abnormality and pachygyria (thick gyri) is a more focal or multifocal abnormality. The basic abnormality, seen on imaging and on gross pathologic examination, is the smooth surface of the cerebral cortex. The cortex is also noticeably thickened with a relative abundance of gray matter, compared to white matter which is variably preserved. There are at least 2 types of lissencephaly (2).

Autosomal and X-linked forms of type I lissencephaly have been identified, but this type may also be associated with other syndromes such as the Miller-Dieker Syndrome (about 15% of cases) (5). A cross-section of the brain reveals an extremely thick cortex organized into four abnormal layers, rather than the usual six. In type I lissencephaly, seizures and severe mental/psychomotor retardation are present. Most cases of type I present in the neonatal period with marked hypotonia, and later with weakness in all four extremities. In the Miller-Dieker syndrome, characteristic facial features are present in childhood and include a prominent forehead, bitemporal hollowing, a short nose with anteverted nostrils, a prominent upper lip, and jaw abnormalities. Lissencephaly as an isolated abnormality is distinguished from the Miller-Dieker Syndrome based on these facial characteristics. Diagnosis of lissencephaly is based on the smooth surface finding along with a widely opened Sylvian fissure on neuroimaging. Cytogenetic studies may often reveal a deletion on the LIS-1 (lissencephaly gene) in chromosomal region 17p13.3. Treatment of the disorder involves seizure medications and supportive care. The prognosis for type I lissencephaly, when associated with other entities, is generally poor and many patients do not survive into childhood.

The inheritance for type II is autosomal recessive but there has not been any association with a specific gene or locus. In contrast to type I, type II lissencephaly is often associated with congenital muscular dystrophies that often involves the eyes as well. Examples are the Walker-Warburg syndrome and the Finnish muscle-eye-brain disorder. In type II lissencephaly the surface of the cerebral cortex usually presents as a diffuse smooth brain appearance. A cross-section reveals an increased thickening of grey matter. Clinical manifestations, when seen with associated muscular dystrophies will involve abnormalities of muscle and CNS development. This may include neonatal hypotonia and eye abnormalities (e.g., retinal dysplasia, cataracts, microphthalmia), and joint contractures. Laboratory results reveal elevated creatine kinase levels (from the muscular dystrophy). Diagnosis is made by careful examination of the MRI of the cortex. Treatment and prognosis of type II is basically the same as in type I.

Polymicrogyria (also known as microgyria, meaning small gyri) is also considered to be a migrational disorder (defects seem to occur between week 17 to 18 and weeks 24 to 26 gestation). Unlike lissencephaly and pachygyria, the border between the polymicrogyria and normal cortex is distinct. Polymicrogyria usually reveals a cerebral cortex with a complex set of small gyri appearing fused together. This gives the surface of the cortex a fine stubbling appearance. A number of malformations and abnormalities have polymicrogyria as one part of an overlying CNS manifestation. For instance the polymicrogyria-schizencephaly complex is a disorder with clinical features including delayed development, pyramidal signs, motor speech dysfunction and epilepsy. Schizencephaly (means cleft brain) is the presence of fused or unfused, unilateral or bilateral clefts within the cerebral hemispheres as a result of abnormal morphogenesis (3). Polymicrogyria presents with psychomotor retardation and frequent focal seizures. The differential diagnosis for this disorder can include Aicardi's, Neu-Laxova, Zellweger, and Smith-Lemli-Opitz syndromes. Removal of a focal area of polymicrogyria may be curative. Multifocal removal may result in improved seizure control. The prognosis is variable, but usually poor.

Cerebral heterotopia are defined as focal or multifocal disorganized nodules of gray matter at inappropriate places in the cerebrum. The heterotopia may be found incidentally on imaging or there may be associated clinical manifestations that present itself. The main presenting feature is a childhood seizure disorder of various types including focal, multifocal, and generalized. Motor and mental retardation may also be present depending upon the extent of the heterotopia abnormality. Focal area heterotopia removal may improve seizures (2). 

Department of Pediatrics, University of Hawaii John A. Burns School of Medicine.

Kaipo T. Pau 

December 2002 

Neural Tube Defects

Neural tube defects (NTDs) are a group of birth defects which are associated with a defective closure of the neural tube and the subsequent development of the central nervous system (brain and spinal cord). It is one of the most common birth defects occurring in approximately 0.7-1.0 per 1000 live birth each year (1,2). There are three types of NTDs: anencephaly, encephalocele, and spina bifida. Spina bifida, the most common NTD, means "split spine" in Latin and is a result of failure of the neural tube to close during the 3rd-5th week of pregnancy. The terminology can be confusing since multiple terms have been used for various conditions depending on the extent of the involvement of the spinal cord and surrounding structures.

Spinal dysraphism and spina bifida apply to a heterogeneous group which has defects of closure affecting the spinal canal (which may encompass the meninges and spinal cord itself in addition to bony vertebral elements). Myelodysplasia refers to defects of spinal cord development, which commonly occurs with spina bifida; however not necessarily associated with failure of fusion of the arches of the vertebral spine, so this could include entities such as syringomyelia and diastematomyelia. Spina bifida occulta is the simple failure of fusion of the spinal arches (i.e., bony involvement only), such that the neural elements are covered by skin and do not protrude above the level of the back. Occult spinal dysraphism means that spina bifida occulta is present with overlying cutaneous markers such as dimple, fistula, hair patch, and hemangioma. These markers may indicate the presence of cord tethering with a lipoma or a dermoid cyst. Spina bifida cystica is the commonest type of NTD which includes meningocele, meningomyelocele/myelomeningocele, lipomyelomeningocele. A meningocele is a lesion which does not involve neural elements in the cystic outpouching of the meninges. Meningomyelocele or myelomeningocele means that dysplastic neural elements protrude through the unfused vertebral arches. It can be completely covered with meninges and skin (closed meningomyelocele) or there may be a connection of spinal fluid to outside (open meningomyelocele). Lipomeningocele and lipomyelomeningocele are closed meningomyelocele with overgrowth of fatty tissue involving the meninges alone or including the spinal cord. The term spina bifida is ambiguous in that it is often used to describe conditions from spina bifida occulta to spina bifida with myelomeningocele.

The manifestations of the spina bifida depend on the level of the spinal cord involvement at which neural tube closure was incomplete. The lesion is located in lumbosacral area in more than 80% of the cases (3).

Children with the less common thoracic lesions, have flaccid paralysis of lower extremities with variable weakness in abdominal and trunk musculature. These defects are frequently associated with serious complications (e.g., respiratory compromise). Children with high lumbar lesions (L1, L2) have flaccid paralysis of knees and ankles and may walk with extensive braces and crutches. Children with midlumbar lesions (L3) have paralyzed ankles and toes. These children can accomplish independent ambulation with braces. Children with low lumbar lesions (L4, L5) often have weak ankle and toe mobility. They are particularly prone to ankle or foot deformities and often need orthosis for independent ambulation.

Bladder and bowel problems are present in more than 90% of children with meningomyelocele regardless of the level of lesion (1). Some children may have problems with bladder emptying, while others may have problems with storing the urine adequately. Despite the type of neurogenic bladder, it is crucial to prevent urinary tract infections and protect the upper urinary tract since renal failure is one of the important causes of death among these children. Bowel continence requires normal external sphincter control, internal sphincter reflex relaxation, rectal sensation and colonic motility. Lack of sensation and inability to control external sphincters makes these children unable to sense or control stool passage. Bowel management programs with regularly scheduled toileting, use of stool softeners, and dietary measures (i.e., additional fiber) are important to avoid constipation and soiling.

Spina bifida is often not only an isolated birth defect of the spinal cord and spine, but there commonly are associated congenital malformations of the brain. Hydrocephalus is a major complication of meningomyelocele and is present at birth in 85-95% of cases as shown by ultrasonography (3,4). These children with hydrocephalus require ventriculoperitoneal shunt (VP shunt) placement. Shunt malfunction and infection are frequent complications and most children eventually require shunt revision (30-40% within one year of insertion of the shunt). Lethargy, vomiting, irritability, bulging and tense fontanelle, and headache, are common symptoms of shunt malfunction. Seizures also occur in up to 17% of the children with meningomyelocele and almost always occur in those with hydrocephalus (5).

Arnold-Chiari II malformation (the cause of the hydrocephalus) is present in the majority of children with meningomyelocele. The cerebellum and medulla oblongata are shifted caudally, so this resultant packing into the cervical spinal canal results in deformation. The symptoms are due to progressive hydrocephalus (if untreated) and dysfunction of the lower cranial nerves, respiration and swallowing. Hydrocephalus occurs in most children secondary to aqueductal stenosis or obstruction to CSF flow around the medulla.

Any clinical changes in children with meningomyelocele should prompt a search for an underlying cause. By far, the most common cause of deterioration is shunt malfunction. Another important cause is tethering of the spinal cord. Up to one third of children with myelodysplasia may experience spinal cord tethering. A tethered spinal cord results from traction on the conus medullaris and cauda equina, which causes spinal cord stretching and ischemia with subsequent loss of neurological function. Symptoms of a tethered spinal cord include spasticity, weakness, decreased sensation in the lower extremities, changes in urinary and bowel functions, or back pain, progressive scoliosis and foot deformity. Some children with occult spinal dysraphism (i.e., no overlying meningomyelocele) are asymptomatic and truly have an occult spinal cord condition. An MRI scan will identify the spinal abnormality. Surgery is indicated in symptomatic patients. Prophylactic intervention among asymptomatic children can prevent the long-term disabilities associated with this condition.

Mastery of bowel and bladder continence is crucial to optimal functioning and is of the major importance for social acceptance. The voiding program may include medications, intermittent catheterization, and possibly operative reconstruction. Clean intermittent catheterization is the most commonly used method to help urinary continence. It is used to remove residual urine, improve urinary drainage, and provide decompression. The goal is to have this task accomplished by early school age. A child's physical abilities and psychological readiness for toileting should be assessed and continued assistance may be necessary for some children.

Children with physical disabilities are often described by their disabilities, and not by their strengths or abilities, which are also important. Children with spina bifida are often automatically placed in regular classes or classes for children with orthopedic problems. Although this is frequently the best placement, there are children whose orthopedic problems are secondary and their learning disability associated with spina bifida may be the major disability. Children with spina bifida and hydrocephalus may have problems with motor skills, attention, memory and organization. These issues should be understood and addressed in the Individualized Education Program (IEP).

Latex allergy has been common among children with spina bifida (about 20-70%) (6). Although the cause of latex allergy in children with spina bifida is not known, it may be due to the early, intense, constant exposure to rubber products among these children. Latex comes from the sap of the rubber tree Hevea brasiliensis. After the commercial purification process there are small amount of residual proteins that could cause allergy symptoms ranging from mild skin rashes or sneezing to hives, respiratory distress and anaphylactic shock. 

Many products contain rubber components of which we are unaware and environmental exposure to rubber products in both the community and hospital is widespread (e.g., rubber bands, erasers, gym mats, certain paints and glues, elastic waist or leg bands in clothing and disposable diapers). There are some food items (e.g., bananas, avocado, chestnuts) which can also cause cross-reactions. Prevention is the best approach. This allergic condition should be documented on medical and school records, communication devices such as medical alert bracelet should be provided as well as auto-injectable epinephrine as a part of the emergency plan for these children. In fact, it is commonly recommended that all children with spina bifida and/or myelodysplasia be kept latex free even if allergy has not yet been demonstrated.

The initial treatment for spina bifida is early surgical closure of the defect. Because of the multisystem involvement of this condition as stated above, management of this condition requires a comprehensive, multidisciplinary team approach. This team may include pediatricians, nurses, specialists (neurologists, neurosurgeons, urologists, orthopedists, developmental-behavioral pediatricians), physical therapists, occupational therapists, social workers, and special education teachers.

Alpha-fetoprotein (AFP) is elevated in maternal serum (MSAFP) and amniotic fluid (AFAFP) in open NTDs such as encephalocele, meningomyelocele and anencephaly. It is also increased in other conditions such as abdominal wall defects (gastroschisis and omphalocele). AFP becomes measurable in maternal serum at the end of first trimester. Maternal blood sample measurements are collected between 16-18 weeks of gestation to provide enough time for more definitive testing as necessary and to allow sufficient time for decision making regarding continuation or termination of an affected pregnancy. The MSAFP level is affected by gestational age and the number of fetuses. Elevated AFP level in amniotic fluid is more definitive than MSAFP, identifying 90-95% of affected fetuses with open NTDs. Acetylcholinesterase assay is more specific for neural tissue with a 99% accuracy rate. Ultrasonography also has been increasingly accurate in prenatal diagnosis of fetal anomalies.

Folic acid is a synthetic compound used in dietary supplements and fortified foods. The term folate includes all compounds that have the vitamin properties of folic acid (folic acid and naturally occurring compounds in food). The average diet in the United States contains 200 microgram of naturally occurring folate, which is less bioavailable than folic acid. Studies have demonstrated that 50% or more NTDs can be prevented if women consume a folic acid supplement before and during the early weeks of pregnancy. The American Academy of Pediatrics endorses the US Public Health Service recommendation that all women capable of becoming of pregnant consume 400 microgram of folic acid to prevent NTDs.

Studies have shown improved long term outcome regarding ambulation, urinary continence, and social continence of stool. One of the studies also showed that about 60% of children with spina bifida attended regular school programs. These outcomes depend on the level of lesion and the severity of complications. 

Department of Pediatrics, University of Hawaii John A. Burns Schoolof Medicine.

Mari Uehara, MD 

October 2002