6. Eye movements
Evaluation of eye movements does not help in immediate management, but provides a useful prognostic guide.
Eye movements may occur spontaneously, or can be elicited reflexly (page 30) by head rotation (oculocephalic reflex) or by caloric stimulation (oculovestibular reflex).
spontaneous oculocephalic oculovestibular reflex spontaneous oculocephalic oculovestibular reflex
Abnormal eye movements may result from: brainstem dysfunction, damage to the nerves supplying the extraocular muscles or damage to the vestibular apparatus. Absent eye movements relate to low levels of responsiveness and indicate a gloomy prognosis.
At the beginning of the century, the eminent neurosurgeon Harvey Cushing noted that a rise in intracranial pressure led to a rise in blood pressure and a fall in pulse rate and produced abnormal respiratory patterns. In the past, much emphasis has been placed on close observation of these vital signs in patients with head injury. These changes, however, may not occur and when present are usually preceded by deterioration in conscious level. This last observation is therefore more relevant.
Basal skull fracture or extracranial injury can result in damage to the cranial nerves. Evidence of this damage must be recorded but, with the exception of a III nerve lesion, does not usually help immediate management. Full cranial nerve examination is difficult in the comatose patient and this can await patient co-operation.
Clinical assessment cannot reliably distinguish the type or even the site of intracranial haematoma, but is invaluable in indicating the need for further investigation and in providing a baseline against which any change can be compared.
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