Individual with intact brainstem may present with doll’s eyes. What is doll’s eye? In the case of doll’s eye, the eye will move laterally towards the side which is opposites to the direction where the head is turned. The Doll’s eye is detected by gentle but the rapid turning of the patient’s head from one side to the other sides. The effect of the doll’s eye is also known as oculocephalic reflexes.
An individual with dysfunction of the brainstem, the doll’s eye effect will be absent. In this situation, the eyes will remain fixed in the mid position while the head is turned from sides to sides. The eyes do not move laterally towards the side opposites to the direction which the head is turned. Any injury to the midbrain or pons which involves the eighth cranial nerve, sixth cranial nerve and third cranial nerve may lead to an absence of the doll’s eye signs. The dysfunction of the brainstem may progress to a deeper coma and presented with an absence of the doll’s eye signs or reversible in some cases.
The doll’s eye sign cannot be assessed on a conscious individual as the eye movement can be controlled voluntarily. The absence of the doll’s eye signs is usually elicited in a comatose patient. Coma is associated with lesions of the brainstem and cerebellum. Absence of the doll’s eye reflex is also important in determining that the patient may be brain death. This situation is implied in the patient who is comatose and suffers from an increase in the intracranial pressure.
There are a few variants of abnormal doll’s eye signs which develop gradually. This abnormal doll’s eye sign is associated with raised in intracranial pressure and metabolic coma. The abnormal doll’s eye sign is presented with loss of conjugate eye movement that cause one eye to remain fixed or move in a direction opposites to the other eye that move laterally.
Neurological examination is performed after detecting the absence of doll’s eye sign. The present of decorticate and decerebrate postures are noted. Glasgow coma scale is used to evaluate the patient level of consciousness. The pupils response to the light, the sizes and equality of pupils are noted. Signs of raised intracranial pressure such as bradycardia, rise in pulse pressure and hypertension are checked.
The common causes of an absence of the doll’s eye signs may include posterior fossa hematoma, pontine haemorrhage, brain stem tumour, brainstem infarction and central midbrain infarction.
A patient who suffers from the posterior fossa hematoma may present with stiff neck, vomiting, headache, confusion, drowsiness, cerebral ataxia, unequal pupils, cranial nerve palsies and dysphagia. These conditions will be worsened with coma and absent of the doll’s eye signs.
Pontine haemorrhage is a life threatening condition. The patient may fall into a deep coma within minutes with an absence of the doll’s eye signs. Pontine haemorrhage may lead to death as the patient condition deteriorates. The patient may suffer from complete paralysis, small but reactive pupils, a positive Babinski’s reflex and decerebrate posture.
A patient who suffers from brainstem tumour may also present with an absence of the doll’s eye sign. This will accompany with comas. Before developing coma, patients may suffer from facial paralysis, loss of sensation, facial pain, nystagmus, hemiparesis, extra ocular nerve palsies, hearing loss, tinnitus, drooling, loss of corneal reflex, ataxia, dizziness, vertigo and vomiting.
Besides causing coma and absent of doll’s eye sign, brainstem infarction may also present with the variability of loss of sensation, muscle flaccidity, decerebrate posture, a positive Babinski’s reflex, bilateral cerebellar ataxia, facial weakness, nystagmus, visual field defect, diplopia, weakness, blindness and paralysis of the limb.
Central midbrain infarction may present with abnormalities of the pupils, nystagmus, contralateral ataxic tremor and Weber’s syndrome (oculomotor palsy that is presented with contralateral hemiplegia, coma and absent of the doll’s eye sign.
A barbiturate which is a hypnotic sedative drug may cause severe depression of the central nervous system which results in an absence of doll’s eye sign or coma.
In children, absent of the doll’s eye sign and coma is more common in situations such as brainstem astrocytoma, near drowning, head injury and near suffocation. The doll’s eye signs may not present during the first ten days of life. It is commonly present at 2 years of age.
In comatose patient who is suspected to suffer from cervical spine injury, it is advisable to avoid performing the test to elicit the doll’ s eye sign as it carries high risk of damaging the spinal cord. As an alternative, cold caloric test is performed to evaluate the oculovestibular reflex. This is performed by instilling the cold water in the ear and in normal individual the eye will move towards the irrigated ear. The cold caloric test is useful to confirm the absence or the present of the doll’s eye sign in trauma patients.
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