Seesaw-Pattern Ocular Bobbing in a Patient With Pontine Bleed

Non-nystagmus hyperkinetic eye movement disorders

BACKGROUND

While nystagmus is an involuntary ocular movement relatively frequent, well described, and easily recognized by most practitioners, non-nystagmus hyperkinetic eye movement disorders (NHEMD) are less obvious and can be overlooked. NHEMD may arise from intrinsic abnormalities in ocular muscles and oculomotor nerves, brain and brainstem lesions, systemic diseases, dysimmune disorders, drugs or can even be functional in nature. Given that some treatable disorders initially manifest with NHEMD, their knowledge becomes crucial.

AIMS

This review aims to offer a practical and comprehensive guide to recognize specific types of NHEMD, to choose the appropriate diagnostic tests and treatments.

RESULTS

The review approaches individual NHEMD based on the location of anatomical lesions and the underlying pathophysiological mechanisms; therefore, it begins with those arising from abnormalities in extraocular muscles or oculomotor nerves (as for example, superior oblique myokymia and ocular neuromyotonia), then moves to NHEMD due to brainstem and brain involvement (as for example, ocular bobbing, opsoclonus, and tonic downward gaze deviation). Lastly, functional NHEMD and nonnystagmus ocular hyperkinesias associated with specific neurological disorders, such as Parkinson's disease or blepharospasm will be considered.

CONCLUSION

Overall, the review offers a comprehensive reappraisal of hyperkinetic disorders of eye motility.

Subtle ocular movements in a patient with brain death

Introduction and Case Presentation: Brain death can be associated with limb movements that are attributed to spinal reflexes. Although head/face movements have been rarely reported, no case of overt eye movements in brain death has been documented. We report a case of a patient with subtle eye movements whose exam was otherwise consistent with brain death. The presence of eye movements delayed pronouncing the patient as brain dead and delayed organ donation. We agree with American Academy of Neurology Position statement from 2019 that brain death does not mean demise of every neuron. Discussion: This case raises important questions about the types of movements that should be "allowed" during the determination of brain death to avoid delays in diagnosis.

Pendular Oscillation and Ocular Bobbing After Pontine Hemorrhage

The pathophysiology of acute, vertical spontaneous eye movements following pontine hemorrhage is not well understood. Here, we present and discuss the video-oculography findings of a patient with acute pontine hemorrhage who developed vertical pendular oscillation and ocular bobbing while comatose. The amplitudes, peak velocities, frequency distribution, and phase planes (velocity versus position) of the eye movements were analyzed. The vertical pendular oscillation was rhythmic with a peak frequency of 1.7 Hz, but amplitudes (mean 1.9°, range 0.2-8.2°) and peak velocities (mean 20.6°/s; range 5.9-60.6°/sec) fluctuated. Overall, their peak velocities were asymmetric, faster with downward than upward. Higher peak velocities were seen with larger amplitudes (downward phase r = 0.95, p < 0.001; upward phase r = 0.91, p < 0.001) and with movements beginning at eye positions lower in the orbit (downward phase r = - 0.64, p < 0.001; upward phase r = - 0.86, p < 0.001). Interspersed were typical ocular bobbing waveforms with a fast (peak velocity 128.8°/s), large-amplitude (17.5°) downward movement, sometimes followed by a flat interphase interval (0.5 s) when the eye was nearly stationary, and then a slow return to mid-position with a decaying velocity waveform. To account for the presence and co-existence of pendular oscillations and bobbing, we present and discuss three hypothetical models, not necessarily mutually exclusive: (1) oscillations originating in the inferior olives due to disruption of the central tegmental tract(s); (2) unstable neural integrator function due to pontine cell group damage involving neurons involved in gaze-holding; (3) low-frequency saccadic intrusions following omnipause neuron damage.