Ocular bobbing

A 68-year-old woman presented with deep coma (E1, V1, and M2) of 2 days duration. On examination the patient had pinpoint sluggishly reacting pupils, absence of extraocular movements on oculocephalic maneuvers, ocular bobbing, and bilateral extensor plantar responses. CT of the patient’s brain documented a large pontine hematoma. The patient died on the fourth day of her illness. Ocular bobbing is a distinctive involuntary vertical eye movement seen in comatose patients with pontine lesions. It is characterized by intermittent, often conjugate, rapid downward movement of the eyes, followed by a slow return to mid-position. As compared to jerk nystagmus, ocular bobbing is much slower in frequency, with the slow phases lasting several seconds. Typical ocular bobbing is associated with extensive pontine destruction (infarction, hemorrhage, tumor, central pontine myelinolysis) or extra-axial posterior fossa masses (eg, cerebellar hemorrhage). Neuroanatomic reasons for ocular bobbing are not clear, but both mesencephalic and medullary burst neuron centers may play a part in its genesis (Rosa et al 1987). Some suggest that ocular bobbing is akin to roving eye movements when horizontal gaze has been severely disrupted. Others suggest that it is because of surviving vestibular nuclei (mediating vertical gaze) in the medulla in patients with pontine lesions. (Contributed by Dr. Ravindra Kumar Garg.)