Sensory Examination
A complete examination of all peripheral sensory modalities is possible only in older children(42). Nevertheless, some modalities can be tested in infants and young children, and provide significant information.
An infant who cries and squirms to move away from pinprick obviously perceives pain(43). A sleepy infant may be slow to respond and requires repeated stimuli. Withdrawal of the leg from painful stimuli may represent the triple flexion spinal withdrawal reflex in thoracic spinal cord lesion and should not be mistaken for active movement and presence of sensation. Comparing the infant's reaction to pinprick on the arms or face differentiates actual sensory perception in such cases. Older infants respond to touch and vibration by turning toward or moving away from the stimulus. Presence of superficial reflexes signals an intact afferent and efferent reflex arc. The neuro- segmental levels are T8-T12 for abdominal reflexes, L1-L2 for the cremasteric reflex, and S4-S5 for the anocutaneous reflex. In spina bifida, absence of these reflexes generally coincides with sensory deficit in the respective dermatomes. In young children who cannot be tested for proprioceptive function, ataxia and incoordination may suggest absence of this sensation. Testing of position sense is usually reliable by school age.Cortical sensory function is impaired in parietal lobe damage (42,44). The most frequent childhood example is hemiparetic cerebral palsy. Disproportionately poor spontaneous function, neglect, and visual monitoring during use of the arm and hand are suspicious signs. Objective evaluation is generally feasible after five to six years of age, using the same technique as in adults for stereognosis, two-point discrimination (45). and topognosia with single or double sensory stimulation. Testing for graphesthesia may be attempted by using a circle or square.
Around eight years of age, the traditional number identification gives more accurate information. Cutaneous sensation and proprioception must be intact, and adequate cognitive ability is a prerequisite for testing cortical sensory function.The child's age and ability to cooperate need to be considered in the examination of special senses. Moving a bright light or attractive object across the visual field is used to test vision in infants. At one month, the infant will follow to midline and at three months, from side to side through a 180-degree arc. The Stycar test and the illiterate E chart are used for screening preschool children at risk for visual deficit (46,47). At an early age, unilateral impairment or loss of vision and visual field defects, such as hemianopsia, are more likely to remain undetected than bilateral deficits. A child with strabismus or suspicion of diminished vision should see an ophthalmologist as soon as the problems are discovered. Early treatment with eye patching or corrective lenses is necessary to prevent amblyopia ex anopsia (48,49). Central dysfunction of visual attentiveness, discrimination, and information processing may be misinterpreted as diminished vision and require both ophthalmologic and neuropsychologic investigation.
Screening of auditory function is a routine procedure in the neonatal nursery, pediatric office, and school. The examination of handicapped infants and children also should include simple screening of hearing, eliciting the blink or startle reflex. Responses by hand clapping to speech of conversational loudness or whisper; perception of finger rubbing near the ear; and reaction to tuning fork, bell, or cricket toy are methods of testing. Absent, lost, or delayed speech, articulation deficits, inattentiveness to sound, a history of recurrent otitis media, head injury, or failure to pass the screening test indicates a need for complete evaluation of auditory function (43,48,50,51).