Upbeat nystagmus as an early sign of cerebellar astrocytoma

Summary A boy with a left-hemispheric cerebellar astrocytoma had upbeat nystagmus exhibiting increasing-velocity slow phases. The nystagmus improved after excision of the tumour.     

Hereditary cerebellar degeneration with downbeat nystagmus. A case and it''s treatment

We present a female patient of 48 years with downbeat nystagmus (DBN), moderate impairment of coordination testing and a family history of cerebellar ataxia. We report that a single 2 mg dose of clonazepam (following Currie & Matsuo) resulted in a virtual disappearance of nystagmus and of the patient's symptom of oscillopsia. This result is interpreted in terms of current models of DBN.     

Perverted head‐shaking and positional downbeat nystagmus in patients with multiple system atrophy

The diagnosis of multiple system atrophy (MSA) is mainly based on the clinical criteria, which are often of little assistance in the early stages of the disease. Positional downbeat nystagmus (pDBN) and perverted head‐shaking nystagmus (pHSN), possible signs of cerebellar dysfunction, may be useful in differentiating MSA from other parkinsonian disorders. To investigate the occurrences of pDBN and pHSN in patients with MSA compared with those in patients with Parkinson's disease (PD). A total of 127 consecutive patients with MSA and 274 patients with PD underwent a video‐oculographic recording of head‐shaking and positional nystagmus over a year. The occurrences of pDBN and pHSN were higher in MSA than in PD. pDBN was more frequently observed in MSA with overt cerebellar signs than in those without, but the occurrence of pHSN did not differ between the MSA groups. pHSN was more frequently observed in MSA‐p without overt cerebellar signs than in PD, but there was no difference in the occurrence of pDBN between them. The presence of pHSN and pDBN may be a clue for the diagnosis of MSA, and pHSN may be helpful in differentiating MSA‐p from PD when the patients do not have overt cerebellar features. © 2009 Movement Disorder Society     

Positional nystagmus and vertigo due to a solitary brachium conjunctivum plaque

The authors describe two patients suffering from demyelinating central nervous system disease who developed intense vertigo and downbeat nystagmus upon tilting their heads relative to gravity. Brain MRI revealed in both cases a single, small active lesion in the right brachium conjunctivum. The disruption of otolithic signals carried in brachium conjunctivum fibres connecting the fastigial nucleus with the vestibular nuclei is thought to be causatively involved, in agreement with a recently formulated model simulating central positional nystagmus. Insufficient otolithic information results in erroneous adjustment of the Listing's plane in off-vertical head positions, thus producing nystagmic eye movements.     

Downbeat nystagmus indicates cerebellar or brain-stem lesions in vitamin B12 deficiency

Summary Two cases of vitamin B₁₂ deficiency caused by gastric atrophy are described. Together with the neuropsychiatric features usually associated with this condition, a downbeat nystagmus syndrome was observed. It is concluded that vitamin B₁₂ deficiency may also result in lesions to those cerebellar or brain-stem structures that are generally assumed to cause downbeat nystagmus.     

Positional vertigo and macroscopic downbeat positioning nystagmus in spinocerebellar ataxia type 6 (SCA6)

To investigate the frequency of positioning nystagmus in degenerative ataxic disorders, we examined downbeat positioning nystagmus (DPN) in 25 patients with spinocerebellar ataxia type 6 (SCA6) and 58 patients with other types of degenerative ataxia. DPN was observed in 21 of the 25 patients with SCA6 (84 %) versus only 3 of the 58 patients (5.2 %) with other types of degenerative ataxia, including multiple system atrophy, SCA1, SCA2, SCA3/Machado-Joseph disease, and non-SCA6 late-onset pure cerebellar ataxia. Our findings indicated that DPN is a distinct part of the clinical presentation of SCA6, showing that vestibular cerebellum is more affected in SCA6 than other types of degenerative ataxia. Received: 11 June 2002, Received in revised form: 24 October 2002, Accepted: 8 November 2002 Correspondence to Hidenao Sasaki, MD, PhD     

Ocular motor control disorder during the neutral phase of periodic alternating nystagmus

Summary Oculographic recordings of refixation saccades and pursuit movements during nystagmus-free intervals in a patient with periodic alternating nystagmus revealed cerebellar ocular motor disturbances that support the hypothesis that cerebellar disinhibition plays a role in the pathogenesis of periodic alternating nystagmus.Fellow in Neuro-Ophthalmology, with grants from Schweizerische Stiftung für medizinischbiologische Stipenden, and Geigy Jubiläumsstiftung Basel     

Finger extension weakness and downbeat nystagmus motor neuron disease syndrome: A novel motor neuron disorder?

Introduction: Disturbances of eye movements are infrequently encountered in motor neuron diseases (MNDs) or motor neuropathies, and there is no known syndrome that combines progressive muscle weakness with downbeat nystagmus. Methods: To describe the core clinical features of a syndrome of MND associated with downbeat nystagmus, clinical features were collected from 6 patients. Results: All patients had slowly progressive muscle weakness and wasting in combination with downbeat nystagmus, which was clinically most obvious in downward and lateral gaze. Onset was in the second to fourth decade with finger extension weakness, progressing to other distal and sometimes more proximal muscles. Visual complaints were not always present. Electrodiagnostic testing showed signs of regional motor axonal loss in all patients. Discussion: The etiology of this syndrome remains elusive. Because finger extension weakness and downbeat nystagmus are the discriminating clinical features of this MND, we propose the name FEWDON‐MND syndrome. Muscle Nerve 56 : 1164–1168, 2017     

Periodic alternating nystagmus and rebound nystagmus in spinocerebellar ataxia type 6.

We report on a family with ataxia type 6 (SCA6) showing peculiar oculomotor symptoms. The proband presented with periodic alternating nystagmus (PAN), and her 2 brothers had rebound nystagmus and gaze-evoked nystagmus. They carried the identical mutation (the number of expanded CAG repeat, 24) in the CACNA1A gene. The intrafamilial variability of oculomotor symptoms may be ascribed to factors other than CAG repeat expansion size in SCA6.     

Divergent effects of deep cerebellar lesions on two different conditioned somatomotor responses in rabbits

Rabbits with bilateral lesions involving either the anterior interpositus nucleus or the superior cerebellar peduncle were subjected to appetitive Pavlovian conditioning training involving repeated pairings of a 2-s tone with an intraoral pulse of water. Such training resulted in the rapid development of robust, anticipatory jaw-movement responses (JM CRs) to the tone, and, in fact, the performance levels exhibited by lesioned animals did not differ significantly from those observed in sham-operated control animals. Additional experiments involving unpaired tone/water presentations confirmed the associative character of the JM CRs. On the other hand, lesioned animals exhibited severe bilateral performance deficits when later subjected to aversive eyeblink conditioning procedures, consistent with previous findings. The present results thus suggest that the interpositus nucleus is not an essential neural substrate for the development of appetitively conditioned masticatory responses.     

Flicker-induced nystagmus in a ganzfeld situation in monkeys

The possibility that flicker-induced nystagmus (FIN) is a form of optokinetic nystagmus evoked by an apparent motion effect was explored in six rhesus monkeys. FIN was elicited by stroboscopic stimulation of one or both eyes directly (heterogeneous field condition), and through a diffuser which approximates a Ganzfeld situation (homogeneous field condition). FIN and afterresponses (FIAN) were easily obtained with monocular stimulation and, in fact, were enhanced in the homogeneous field condition as shown by a shorter latency and higher frequency of FIN, and by longer and more prevalent FIAN with additional reversals. The magnitudes of FIAN were greater following longer stimulation. The build-up period and mean peak frequency were interdependent in the heterogeneous but not in the homogeneous field condition. Binocular flicker, particularly in the latter situation, resulted in a preponderance of FIN to the right, a response characteristic of right eye stimulation. Similarly, in some animals, the response and afterresponses were stronger on flickering the right eye. The results demonstrate that apparent motion does not play a role in the initiation and/or propagation of FIN and FIAN. The enhancement obtained in the Ganzfeld situation suggests the opening of a negative feedback loop which may operate during direct stimulation. The “reafference principle” could explain the relationship of the build-up period and mean peak frequency in the two stimulus conditions. The asymmetric responses obtained in this study reflect a lateralization of function. FIN, as an unlearned form of behavior, could be useful as a model for elucidating the mechanism of such a bias.     

Primary position upbeat nystagmus reversed with carbamazepine

A 16-year old girl presented with primary position upbeat nystagmus (PPUN). MRI showed a small lesion at the perihypoglossal nuclei of the dorsal medulla oblongata. The case was diagnosed as a demyelinating disease for its response to prednisone, and the nystagmus decreased after administration of carbamazepine. Primary position upbeat nystagmus might be caused by an abnormal firing of neurons in the nuclei resulting in a tonic imbalance of vertical gaze. Also this is the first report to confirm the attenuation of PPUN by carbamazepine.     

Primary position upbeat nystagmus

Primary position upbeat nystagmus is a rare clinical finding. We report a patient with clinically isolated syndrome suggestive of multiple sclerosis who presented with primary position upbeat nystagmus. MRI revealed a demyelinating lesion in the lower medulla, which affected the nucleus intercalatus; this type of lesion inhibits the flocculovestibular inhibitory pathway, thereby causing upbeat nystagmus. Nystagmus still persisted after pulsed corticosteroid therapy. This could be due to a loss of central adaptation of the vestibulo-ocular system in our patient, because of more diffuse brainstem damage, shown on vestibular-evoked myogenic potentials as delayed latencies on both sternocleidomastoid muscles and a conduction block for the left extraocular muscles.     

Unilateral internuclear ophthalmoplegia and ipsiversive torsional nystagmus

We report four patients with internuclear ophthalmoplegia and torsional nystagmus, ipsiversive to the side of the medial longitudinal fasciculus (MLF) lesion. The MLF lesion could be responsible for an inactivation of the ispilateral interstitial nucleus of Cajal inducing a contraversive slow phase. The presence of a corrective ipsiversive quick phase implicates an intact rostral interstitial nucleus of the MLF.     

Downbeat nystagmus in two siblings with spinocerebellar ataxia type 6 (SCA 6)

We report two siblings with spinocerebellar ataxia type 6 (SCA 6), both showing downbeat nystagmus (DBN) as a predominant clinical feature. Familial hemiplegic migraine (FHM), episodic ataxia type 2 (EA-2) and SCA 6 are allelic disorders, and interestingly, the occasional presence of DBN in EA-2 was reported. Our observations suggest that common molecular mechanisms might underlie DBN in FHM, EA-2 and SCA 6. Then, these disorders should be kept in mind in diagnosing patients with DBN.     

Anti-Yo positive paraneoplastic cerebellar degeneration: a report of three cases and review of the literature

Anti-Yo is an anti-Purkiney cell cytoplasmic antibody found in approximately 50% of patients with parancoplastic cerebellar degeneration (PCD). We report three patients with anti-Yo positive PCD (one ovarian carcinoma and two poorly differentiated adenocarcinomas consistent with breast origin). Two were treated with chemotherapy and plasmapheresis but died within months of the diagnosis from progressive neurological disease. The other was given gamma-globulin and has remained table at 6 months follow up. Anti-Yo antibodies are highly specific with almost all patients having breast or gynaecological malignanies. Commonly the tumour is of small volume and asymptomatic. Attempts at treatment are usually unsuccessful but there are a number of reports of stabilisation or improvement when treatment is begun before the development of severe neurological disability. The detection of anti-Yo antibodies is very useful for the diagnosis of PCD allowing early tumour detection and prompt institution of treatment.