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.     

Skeletal myoclonus in olivopontocerebellar atrophy: treatment with trihexyphenidyl

We studied two patients with nonfamilial olivopontocerebellar atrophy with skeletal myoclonus. Palatal or skeletal myoclonus is probably not a coincidental finding but another manifestation of the underlying disease. In both cases, the myoclonus was suppressed by administration of trihexyphenidyl, indicating a cholinergic disorder.     

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.     

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.     

Rhythmic palatal myoclonus and the dentato-olivary pathway

Summary The anatomical basis of palatal myoclonus and related rhythmic skeletal myoclonus is described. The most constant lesion is a special type of degeneration with hypertrophy of the olivary nucleus of the medulla oblongata, on the side opposite to the myoclonus when it is unilateral. This degeneration is usually secondary to a primary lesion located either in the ipsilateral (to the hypertrophied olive) central tegmental tract or in the contralateral dentate nucleus. To link these data, Trelles (1935, 1943) suggested a dentato-olivary pathway from the dentate nucleus to the contralateral inferior olive via the superior cerebellar peduncle and the central tegmental tract after crossing the midline. The existence of this pathway was demonstrated by Lapresle and Ben Hamida (1965–1971), first by showing a topistic relationship between dentate nucleus and contralateral inferior olive, then by delineating this pathway in the vicinity of the red nucleus at the crossing of the superior cerebellar peduncle and the central tegmental tract. The significance of these lesions with their ensuing symptoms is discussed. It is considered as a transsynaptic degeneration which probably reveals an archaic phenomenon, submerged but not lost through evolution.Lecture given at Nagoya University School of Medicine, Japan, on 16 October 1978     

Benign segmental myoclonus: electrophysiological evidence of transient dysfunction in the brainstem.

We present a 66-year-old patient with segmental myoclonus evoked by a brainstem infarction. The myoclonus appeared soon after a cerebrovascular accident and it was evident in the soft palate, jaw, neck, shoulders and upper limbs. Brain MRI showed infarction in the left pons and left cerebellum. Small amounts of orally administered clonazepam were remarkably effective. Electroencephalogram (EEG) and auditory brainstem response (ABR) were normal. Somatosensory evoked potential (SSEP) revealed delays in P 14 and N19 recorded at C3 by right median nerve stimulation. These findings were normalized in 4 days. Seg-mental myoclonus is thought to be evoked by olivary hypertrophy following cerebrovascular accident in the brainstem and is said to be resistant to medication. The limited involvement of the brainstem in our patient may account for the transient segmental myoclonus. The prognosis for this type of segmental myoclonus is excellent.     

Unusual CT and MRI findings in palatal myoclonus

A 23-year-old man suffered from palatal myoclonus for 2 years. It had appeared one week after a minor head trauma. MRI and basal cisternography revealed a localized atrophy of the left paramedian part of the medulla, encroached upon the left vertebral artery. Clonazepam treatment was beneficial. This particular case is discussed in relation to etiopathogenesis and other causes of palatal myoclonus.     

Autosomal dominant palatal myoclonus and spinal cord atrophy

We report a new family with palatal myoclonus, pyramidal tract signs, cerebellar signs, marked atrophy of the medulla oblongata and spinal cord, and autosomal dominant inheritance. These findings were almost identical with those in patients previously reported to have histopathologically confirmed adult-onset Alexander disease. Recently, heterozygous point mutations in the coding region of glial fibrillary acidic protein (GFAP) in patients with an infantile form of Alexander disease have been reported. We found a new heterozygous amino acid substitution, Val87Gly in exon 1 of GFAP, in the affected individuals in this family but not in 100 spinocerebellar ataxia (SCA) patients and 100 controls. Therefore, this family might have new clinical entities related to adult-onset Alexander disease and GFAP mutation.     

Memory dysfunction in myasthenia gravis: evidence for central cholinergic effects

Two studies are presented that investigate the possible central cholinergic effects of myasthenia gravis as measured by cognitive dysfunction. In the first study, performance on a battery of cognitive tasks by 12 subjects with myasthenia gravis is compared with that of ten healthy control subjects and ten medical control subjects with chronic disease of a nonneurologic nature. The tests used were the Boston Naming Test, Rey Auditory Verbal Learning Test (AVLT), and the Logical Memory and Design Reproduction portions of the Wechsler Memory Scale (WMS). Results indicate that the myasthenic group was significantly impaired relative to both the medical and healthy control groups for performance on the Boston Naming Test, WMS Logical Memory, and WMS Design Reproduction. Both the myasthenic and the medical control groups were impaired relative to the healthy controls on the AVLT. In the second study, a myasthenic patient had plasmapheresis for treatment of her myasthenia on two separate occasions. Her memory was examined prior to as well as following each series of plasma exchanges with a variation of the Peterson-Peterson consonant trigram task. Results showed that this patient had significantly fewer interference effects and less rapid forgetting following plasmapheresis. The results of these two studies support the hypothesis that myasthenia gravis has central cholinergic effects manifested by cognitive dysfunction.     

Symptomatic palatal myoclonus: an unusual cause of respiratory difficulty

A 67-year-old man presented with dysphagia and difficulty breathing. Physical examination revealed palatal myoclonus. In this patient, the respiratory difficulty was caused by the fragmentation of breathing. Electromyographic examination of the cricothyroid muscle demonstrated rhythmic myoclonic jerks. Magnetic Resonance Imaging (MRI) yielded a pontine midline and right sided tegmental infarct. The patient responded to sodium valproate.