He had been vomiting excessively, felt to be associated with his chemotherapeutic regimen. Note horizontal greater than vertical gaze evoked nystagmus, consistent with marked involvement of the nucleus prepositus hypoglossi bilaterally (figure 18.32), impairing gaze holding functions. Thiamine levels were found to be very low — following parenteral replacement, his vision, ocular motor abnormalities, and neuroimaging findings markedly improved.

She underwent sub-occipital decompression in attempt to improve her significant oscillopsia (see video 18.6).

9 months later, she developed this vertical dysconjugate pendular nystagmus, and subtle, synchronous palatal movements. She responded well to gabapentin 1800 mg daily, titrated up to this dose over 3 months.

These abnormalities localize to compression of the dorsal vermis and floccular purkinje fibers.

This is accompanied by upbeat nystagmus, more prominent in upgaze, resulting from interruption of the ventral tegmental tract (VTT) which course longitudinally through the paramedian pons and midbrain, immediately adjacent to the MLF fibers. The VTT carries vestibular (slow phase) signals to the the inferior oblique (IO) and superior rectus (SR) subnuclei from the superior vestibular nuclei (SVN), allowing slow (smooth) upward eye movements. Conversely, interruption of VTT fibers leads to a tonic downward slow drift of the eyes, followed by compensatory corrective upward saccades (fast phase), resulting in upbeat nystagmus.

On evaluation, he exhibited macrosaccadic oscillations in all field of gaze and rhythmic movements of his cricoid cartilage were noted on external inpection. Soft palate undulations were observed, occurring simultaneously to the disordered eye movements.

MR imaging revealed vascular compression of the subarachnoid portion of the left facial nerve.

8 months prior, he had experienced a pontine cavernoma hemorrhage.

Follow-up of 7 years with repeat PET and fully body MR imaging has not revealed an underlying malignancy. Note gaze-evoked nystagmus in all fields of gaze suggesting floccular involvement, and hypermetric saccades (vertical, horizontal) indicative of bilateral fastigial nuclei overactivity due to lack of their inhibition by the overlying purkinje cells (PC). The PC are preferentially attacked by the GAD antibodies.

Note bilateral symmetric increased blinking with intermittent eyelid spasms.

Note that the patient varies from a paretic phase to a spastic phase.

Note that the abduction movement is initiated well; however, partially through the conjugate gaze trajectory, his eyes become dysconjugate, due to a convergence movement overcoming abduction. During convergence, note pupillary miosis, which is a telltale sign of convergence excess. This eye movement abnormality, when occurring in isolation (eg. no other features of Parinaud's syndrome or lesions involving the thalamo-mesencephalic region) is considered non-organic in nature.

The incyclotorsion is best observed by asking the patient to abduct the eye, then attempt infraduction (hence isolating the paretic inferior rectus (IR)). Given the lack of IR function, the superior oblique takes over as the only available depressor, incyclotorting the eye as this is its primary action. Observing a radially oriented conjunctival vessel allows for easier appreciation of the cyclo-rotation. Lack of observed incyclotorsion in this setting should raise suspicion for fourth nerve involvement in addition to the oculomotor palsy.

During the paretic phase, note ptosis, deficits in adduction, elevation, depression and relative mydriasis of the left pupil. This gives way to a period of spastic contraction, producing upper eyelid retraction, esotropia, and miosis.

This results from a delay in relaxation of the inferior rectus even after the voluntary stimulus to infraduct is extinguished.

Periodic reversal of the nystagmus direction was seen, indicating a torsional PAN.

The clinical findings are indistinguishable from those of the previous patient, emphasizing the need for imaging in all patients with spasmus nutans.

Note weakness of the left side of the face associated with synkinesis between the orbicularis oculi and orbicularis oris muscles; ie, when the patient gently closes her left eye, the left corner of her mouth and left side of the face tighten, whereas when the patient moves the left side of the mouth, the left eyelid closes.

Note dampening of nystagmus with extreme lateral gazes. The patient also has a skew deviation from her demyelinating disease.

Note that the patient has normal responses when the optokinetic drum is rotated toward his right side but blunted responses when the drum is rotated toward his left side (the side of the lesion). (Courtesy of Drs. David L. Knox and Megan Collins).

Attempted blinks reveal facial weakness. Note preservation of vertical gaze and convergence.

Note the decreased adduction velocities bilaterally, and constant, high frequency upbeat nystagmus.

During attempted lateral gaze in either direction, nystagmus of the abducting eye is observed.

After looking down for 15 seconds, the patient is asked to look straight ahead. The more ptotic right upper lid in particular shows over-elevation before settling into primary position.

Note that after about 10 seconds of downward gaze, followed by a saccade back to primary position, the right upper eyelid elevates normally but then immediately goes downward. The left upper lid shows a similar but less impressive phenomenon.

Determination of the direction (incyclotorsion vs excyclotorsion) and amount of torsion can readily be achieved with the use of this subjective, yet quantifiable test.

She also had pursuit-saccadic dissociation (not shown here).

Amplitude increases on downgaze (Alexander's law) and also upon lateral gaze.

Note marked increase in ptosis on the left when the right upper eyelid is raised. There is only minimal increase in ptosis on the right when the left upper eyelid is raised.

The patient has bilateral ptosis, and elevation of either eyelid results in increased (enhanced) ptosis on the opposite side.

Note the marked improvement in downbeat nystagmus in primary position (only residual, small amplitude, low frequency), with some persistence in lateral fields, albeit much improved from pre-operative state.

With attempted abduction of either eye, eyelid elevation occurs.

Followed by inspection, saccades, smooth pursuit, ductions, and versions can all be assessed in a quick and informative manner. Paying attention to laterncy, velocity an accuracy of the eye movements can provide valuable information about the integrity of the underlying systems and help direct further clinical and ancillary examinations.

Starting in darkness, anisocoria is present but of small magnitude. With light, both pupils show brisk constriction, and anisocoria is accentuated when the light is turned off because of dilation lag in the affected eye (Courtesy of Randy H. Kardon, M.D., Ph.D.)

Note larger pupils than seen in Video 15.2.

The condition resolved within 3 weeks after she reduced her caffeine intake.

Courtesy of Randy H. Kardon, MD, PhD.

Pupils are small bilaterally and show virtually no reaction to a bright light stimulus, but brisk bilateral constriction to a near target.

She had no other neurological symptoms or findings, and an underlying cause for her condition was not found despite extensive radiographic and serologic workup.

Note not only blepharospasm but involuntary movements of the mid and lower face on both sides.

Such patients almost universally have bilateral pontine insults. Courtesy of David Zee, MD. Reproduced with permission from Oxford University Press, USA.

At baseline, she has a mild partial right CN III palsy with ptosis and a slight exotropia. With sustained left gaze, there is progressive right upper eyelid elevation and right eye adduction, such that when she returns to primary position, she has a manifest esotropia. She had chronic compression of the right CN III by the posterior communicating artery. From Cruz et al. Partial Third Nerve Palsy and Ocular Neuromyotonia From Displacement of Posterior Communicating Artery Detected by High-Resolution MRI. J Neuroophthalmol 2013;33:263-265.

The convergent-divergent nystagmus is not associated with globe retraction, unlike the nystagmus of Parinaud syndrome, and occurs in all horizontal gaze positions with accompanying rhythmic mastication. The final segment (in color) shows the same patient after treatment. (Courtesy of John B. Selhorst, MD).

An initially left beating jerk nystagmus nearly stops and then becomes a right beating nystagmus.

Note involvement of the right forehead, eyelids, cheek, and lips.

Defect is easier to appreciate in upgaze.

Courtesy of Dr. Eric Eggenberger.

The first child has the classic triad of head bobbing, anomalous head posture, and nystagmus. The nystagmus is essentially monocular in this child, while in the infant it is asymmetric. Both children were examined prior to routine availability of neuroimaging, and findings resolved by age 5.

Courtesy of David Newman-Toker, M.D., Ph.D.

This patient presented with intermittent monocular (right eye only) vertical and torsional oscillopsia. Note the frequent torsional, with slight vertical movements of the right eye, lacking a regular pattern. Occasionally, patients may demonstrate a vertical misalignment during the attacks, due to over- or underaction of the affected superior oblique. These monocular, involuntary movements can be well observed at the slit lamp under magnification. Observing a conjunctival landmark such as a radially oriented vessel, or as in this case, a pingueclum, can also be helpful.

Because this ability depends on proprioception and not on vision, truly blind patients should be able to perform this task.

Note there is gaze-evoked nystagmus that is separate from this phenomenon. From Nguyen and Borruat. Teaching Video NeuroImages: Heimann-Bielschowsky phenomenon. Neurology 2018;90:e731.

A large mirror is held in front of the patient's eyes (if the patient claims no or little vision in both) or in front of the patient's supposedly non-seeing eye. It is then rotated from side to side. Patients with visual acuity of 20/400 or better will be unable to keep their eyes steady because the visual environment in front of them is moving.

Note not only bilateral ptosis and ophthalmoplegia but also dilated, non-reactive pupils. The patient was quadriparetic but had no sensory deficits and was alert and awake. She was treated with supportive care and eventually made a full recovery.

She displays intermittent involuntary contractions of the pretarsal orbicularis muscle, making it difficult for her to keep her right eye open. Local injections of small doses of botulinum toxin in the superior pretarsal orbicularis muscle were beneficial.

This patient was referred for evaluation because of episodic blinking behaviors. Although he does blink abnormally, the additonal lip smacking, left-sided facial contraction, and sudden head movements are characteristic of a motor tic and not benign essential blepharospasm.

Although he carried a diagnosis of pulmonary sarcoid, neuroimaging did not support this diagnosis, and the underlying cause could not be identified with certainty. (Courtesy of Dan Gold, DO.)

Note the unsustained, rapidly alternating, high-frequency saccades.

Note mild deficit of abduction bilaterally (pseudo-abducens palsy) presumably due to increased convergence tone, as well as symmetric upgaze limitation. On attempted upgaze, marked convergence-retraction nystagmus is appreciated.