Acquired pendular nystagmus in multiple sclerosis: clinical observations and the role of optic neuropathy.

Thirty seven patients with pendular nystagmus due to multiple sclerosis were reviewed. Most developed nystagmus later in a progressive phase of the disease. All had cerebellar signs on examination and evidence of optic neuropathy. MRI in eight patients showed cerebellar or brainstem lesions in seven; the most consistent finding was a lesion in the dorsal pontine tegmentum. Dissociated nystagmus was seen in 18 patients: in these the signs of optic neuropathy were often asymmetric and the severity correlated closely with the side with larger oscillations. This suggests that dissociations in acquired pendular nystagmus may be due to asymmetries in optic neuropathy rather than asymmetries in cerebellar or brainstem disease.     

Acquired pendular nystagmus with oscillopsia in multiple sclerosis: a sign of cerebellar nuclei disease

In an unselected series of 644 cases of multiple sclerosis, 25 cases with acquired pendular nystagmus were found. Ten additional cases of pendular nystagmus in multiple sclerosis were investigated, and four cases from the literature are analysed. Acquired pendular nystagmus is purely sinusoidal in form, ceases with eye closure, is accompanied by oscillopsia, often monocular and vertical in direction, and never accompanied by optokinetic inversion. This is different from congenital nystagmus. Acquired pendular nystagmus in multiple sclerosis shows a high correlation with holding tremor of head and arm and with trunk ataxia, and must therefore be viewed as a result of lesions of cerebellar nuclei or their fibre connections with the brain-stem. Supporting evidence is discussed. The results fit into a theory of cerebellar function according to which the cerebellar nuclei are involved in the maintenance of positions.     

Drug therapy for acquired pendular nystagmus in multiple sclerosis

Acquired pendular nystagmus (APN) is regularly accompanied by oscillopsia and impairment of static visual acuity. Therapeutic approaches to APN remain controversial, and there is no generally accepted therapeutic approach. We tested 14 patients who had suffered from APN caused by multiple sclerosis for several years; 12 patients presented with fixational pendular nystagmus (increasing during fixation) and 2 with spontaneous pendular nystagmus. All 11 patients with fixational pendular nystagmus who were given memantine, a glutamate antagonist, experienced complete cessation of the nystagmus. In contrast, scopolamine caused no (6 of 8) or only a minor (10–50%) reduction of the nystagmus (2 of 8). It was concluded that memantine is a safe treatment option for APN. Received: 29 August 1995 Received in revised form: 6 August 1996 Accepted: 19 August 1996     

Acquired pendular nystagmus in multiple sclerosis: an examiner-blind cross-over treatment study of memantine and gabapentin

A prospective examiner-blind, cross-over study was conducted to compare the efficacy of memantine (40 or 60 mg/day) and gabapentin (1,200 mg/day) as therapy for acquired fixational pendular nystagmus (APN) in 11 patients with multiple sclerosis. APN was documented in 20 eyes by electrooculography (EOG). The primary objective of the study was an at least 50% reduction in amplitude and/or frequency of APN compared with baseline values in EOG. This aim was reached for 17 of 20 APN-affected eyes with memantine 40–60 mg and for 11 eyes with gabapentin up to 1,200 mg. A complete cessation of APN was achieved in eight eyes (four patients) with memantine 40 mg and in a further four eyes (two patients) with memantine 60 mg. One patient achieved the same benefit with memantine 40 mg and gabapentin. In two other eyes APN completely subsided with gabapentin 1,200 mg only, but not with memantine. Near visual acuity, a secondary outcome parameter, improved by at least 0.1 in 11 of 17 eyes treated with memantine and in 8 out of 16 eyes treated with gabapentin. In summary, memantine and gabapentin are safe and effective treatment options for APN.     

Acquired pendular nystagmus associated with the lesion of tegmentum mesencephali in a patient with probable multiple sclerosis]

A 42-year old woman was admitted to our hospital because of sudden onset of dizziness and oscillopsia. Neurologic examination revealed horizontal, binocular pendular nystagmus, which increase their amplitude on left lateral gaze. She also showed that mild right blephaloptosis, right facial spasms, increased tendon reflexes and positive pathological reflexes of four limbs and mild chorea-like movement of both feet. MRI showed an abnormal high intensity area on a T2weighted and proton density images located at the right tegmentum mesencephali. She was diagnosed as clinically probable multiple sclerosis according to the Poser's criteria. The nystagmus was suppressed by clonazepam and diazepam. To our knowledge, it is a first report of acquired pendular nystagmus associated with the lesion of tegmentum mesencephali. We speculate that the involvement of the tract of paramedian pontine reticular formation causes the nystagmus and the dysfunction of GABAnergic neurons might play an important role of the nystagmus.     

Acquired pendular nystagmus after pontine hemorrhage]

A 60-year-old hypertensive woman had a pontine hemorrhage that caused slight right hemiplegia, deep sensory disturbance on her right side and dysarthria. Three months after the stroke, she was transferred to our hospital for rehabilitation. Approximately 6 months later, she gradually began to complain of the visual oscillation. Continual, unceasing conjugate vertical/rotatory eye movements were observed. Fixation was momentary at best because of an inability to dampen the spontaneous eye movements. Electrooculography (EOG) showed bilateral vertical/rotatory sinusoidal eye movements of 2.5 Hz frequency and 10- to 35-degree amplitude. Both vertical and horizontal optokinetic nystagmus were absent. Caloric stimulation did not evoke any responses bilaterally. There were no rhythmical movements at similar frequencies in other parts of the body such as palatal myoclonus. MRI revealed not only hematoma mainly at the dorsal pontine tegmentum but also hypertrophy of the inferior olive nucleus, suggesting disruption of the central tegmental tract. Lesions of this tract may be one cause of pendular nystagmus. Several drug therapies were investigated for the nystagmus. There was no response to baclofen 15 mg. Trihexyphenidyl 4 mg was discontinued because of drug-induced hallucinations. Tiapride 600 mg and phenobarbital 90 mg were each slightly effective in reducing both frequency and amplitude of nystagmus. Treatment with clonazepam 1 mg resulted in the striking disappearance of nystagmus. She was aware of this and no longer experienced oscillopsia. Despite the visual benefit, however, the patient did not wish to continue this drug because of drowsiness and muscle relaxation. The potential long-term therapeutic application of clonazepam should be further investigated. To our knowledge, there have been no reports of successful treatment in acquired pendular nystagmus with clonazepam. Therefore, based on this favorable experience, it is suggested that clonazepam should be added to the list of potential therapies for pendular nystagmus.     

Acquired pendular nystagmus: its characteristics, localising value and pathophysiology

Investigations were made of 16 patients with acquired pendular nystagmus and a further 32 cases reported in the literature were reviewed. Amongst our own patients two thirds had multiple sclerosis, almost one third a cerebrovascular accident or angioma and two had optic atrophy with squint. The nystagmus took forms which could be monocular or binocular, conjugate or disconjugate and could involve movements about single or multiple axes. Spectral analysis was used to characterise the amplitude and frequency of the movements and to estimate the degree of relationship (coherence) between movements of the two eyes or between movements of one eye about several axes. The oscillations ranged in frequency from 2·5 Hz to 6 Hz, with typical amplitudes between 3° and 5°. In a given patient all oscillations, regardless of plane, were highly synchronised. Somatic tremors of the upper limb, face and palate associated with the nystagmus were often at similar frequencies to the eye movement. The other ocular signs common to all our patients were the presence of squint with failure of convergence. Most patients also had skew deviation or internuclear ophthalmoplegia or both. The major oculomotor systems, that is, saccades, pursuit, optokinetic and vestibulo-ocular reflexes could be intact. It is inferred that the mechanism responsible for the pendular nystagmus lies at a level which is close to the oculomotor nuclei so that it can have monocular effects but is not part of the primary motor pathways. It is possible that this mechanism normally subserves maintenance of conjugate movement and posture of the eyes. The periodicity of the nystagmus is likely to arise from instability in a certain type(s) of neurone, for the associated somatic tremors have similar characteristics and yet involve very different neuronal muscular circuitry. Prognosis for cessation of the nystagmus is poor. In five patients with multiple sclerosis it was suppressed by intravenous hyoscine with, however, unacceptable subsequent side effects.     

Latent nystagmus and acquired pendular nystagmus masquerading as spasmus nutans.

SUMMARY: We used ocular motility recordings to identify the characteristics of a rare combination of conjugate, horizontal jerk, and pendular nystagmus in a 9-year-old boy. The clinical diagnoses were amblyopia, left esotropia, congenital nystagmus, and an apparently uniocular pendular nystagmus that mimicked spasmus nutans. Ocular motility recordings revealed an unusual latent/manifest latent nystagmus, pendular nystagmus with characteristics of an acquired nystagmus, and uniocular saccades. The ocular motor data identified clinically unrecognized types of nystagmus and suggested that the pendular nystagmus was acquired in infancy rather than as a result of failure to develop good vision or binocularity. The presence of uniocular saccades adds to the mounting evidence that individual control for each eye exists in humans.     

Trihexyphenidyl treatment of vertical pendular nystagmus

Vertical pendular nystagmus developed 4 months after massive brainstem hemorrhage due to eclampsia. The symptom markedly improved with chronic trihexyphenidyl treatment.     

Diagnosing children presenting with asymmetric pendular nystagmus

Horizontal asymmetric nystagmus usually occurs in one of three situations: secondary to an intracranial lesion, with monocular visual loss, or as part of the triad that constitutes the diagnosis of spasmus nutans (asymmetric nystagmus, abnormal head posture, head shake). Clinical records of 277 children, presenting with congenital nystagmus over an 8-year period were reviewed. Nystagmus was asymmetric in 24 of 277 cases. Seven of these patients were diagnosed with spasmus nutans. This is a rare condition that is only diagnosed retrospectively based on the absence of any abnormal neuroimaging or electrophysiological findings. Twelve of 24 patients had intracranial pathology and all had abnormal visual evoked potentials (VEPs). Five patients were diagnosed with congenital sensory defect nystagmus including one with albinism, three with congenital cone dysfunction, and one with cone-rod dystrophy. This paper stresses that although neuroimaging is necessary in all patients presenting with asymmetric nystagmus, such nystagmus can also occur with retinal disease or albinism and indicates the importance of non-invasive VEP/ERG testing in all forms of nystagmus.     

Conjugate pendular nystagmus evoked by accommodative vergence

Conjugate pendular nystagmus evoked by accommodative vergence in a healthy 18-year-old girl is described. This is clinically demonstrated to be induced by accommodative convergence, and not related to fusional convergence. The lack of neurological or ophthalmic abnormalities supports the classification of a 'congenital' type of this rare phenomenon. A differential diagnosis is also discussed.     

Is acquired pendular nystagmus always phase locked?

A patient with multiple sclerosis presented with oscillopsia due to an acquired pendular nystagmus that was dissociated in amplitude, being larger in the eye with a relative afferent pupil defect. Eye movement recordings showed an unusual dissociation in nystagmus frequency as well. Although the frequencies differed, the eyes remained phase locked as the right eye was oscillating exactly twice as fast as the left eye.