Progressive Ataxia and Downbeat Nystagmus in the Adult

Abstract Background Cerebrotendinous xanthomatosis (CTX) is a rare but treatable neurometabolic disorder of lipid storage and bile acid synthesis. Whilst CTX is said to present with the classic triad of juvenile onset cataracts, tendon xanthomata and progressive ataxia, the diversity of presentation can be such that the diagnosis may be substantially delayed resulting in permanent neurological disability. Methods A retrospective review of the clinical characteristics and imaging findings of 4 patients with CTX presenting to the Sheffield Ataxia Centre over a period of 25 years. Results Although CTX-related symptoms were present from childhood, the median age at diagnosis was 39 years. Only 1 of the 4 cases had tendon xanthomata, only 2 cases had juvenile onset cataracts and 3 had progressive ataxia with one patient presenting with spastic paraparesis. Serum cholestanol was elevated in all 4 patients, proving to be a reliable diagnostic tool. In addition, cholestanol was raised in the CSF of 2 patients who underwent lumbar puncture. Despite treatment with chenodeoxycholic acid (CDCA) and normalization of serum cholestanol, CSF cholestanol remained high in one patient, necessitating increase in the dose of CDCA. Further adjustments to the dose of CDCA in the patient with raised CSF cholestanol resulted in slowing of progression. Two of the patients who have had the disease for the longest continued to progress, one subsequently dying from pneumonia. Conclusion A high index of suspicion for CTX, even in the absence of the classical triad is essential in reaching such diagnosis. The earlier the diagnosis and treatment, the better the outcome.

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Age-dependent ataxia and neurodegeneration caused by an αII spectrin mutation with impaired regulation of its calpain sensitivity

Scientific Reports ◽

10.1038/s41598-021-86470-1 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Arkadiusz Miazek ◽

Michał Zalas ◽

Joanna Skrzymowska ◽

Bryan A. Bogin ◽

Krzysztof Grzymajło ◽

...

Keyword(s):

Neuronal Development ◽

Neuronal Membrane ◽

Post Translational Modifications ◽

Calcium Dependent ◽

Enhanced Sensitivity ◽

Embryonic Lethal ◽

Progressive Ataxia ◽

Substrate Level ◽

Age Dependent ◽

Excessive Activation

AbstractThe neuronal membrane-associated periodic spectrin skeleton (MPS) contributes to neuronal development, remodeling, and organization. Post-translational modifications impinge on spectrin, the major component of the MPS, but their role remains poorly understood. One modification targeting spectrin is cleavage by calpains, a family of calcium-activated proteases. Spectrin cleavage is regulated by activated calpain, but also by the calcium-dependent binding of calmodulin (CaM) to spectrin. The physiologic significance of this balance between calpain activation and substrate-level regulation of spectrin cleavage is unknown. We report a strain of C57BL/6J mice harboring a single αII spectrin point mutation (Sptan1 c.3293G > A:p.R1098Q) with reduced CaM affinity and intrinsically enhanced sensitivity to calpain proteolysis. Homozygotes are embryonic lethal. Newborn heterozygotes of either gender appear normal, but soon develop a progressive ataxia characterized biochemically by accelerated calpain-mediated spectrin cleavage and morphologically by disruption of axonal and dendritic integrity and global neurodegeneration. Molecular modeling predicts unconstrained exposure of the mutant spectrin’s calpain-cleavage site. These results reveal the critical importance of substrate-level regulation of spectrin cleavage for the maintenance of neuronal integrity. Given that excessive activation of calpain proteases is a common feature of neurodegenerative disease and traumatic encephalopathy, we propose that damage to the spectrin MPS may contribute to the neuropathology of many disorders.

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Therapy-Resistant Atypical Downbeat Nystagmus with Vertigo Confined to Specific Head-Hanging Positions: Mapping to the Gravity Vector on a Multi-Axis Turntable

Case Reports in Neurology ◽

10.1159/000517840 ◽

2021 ◽

pp. 464-469

Author(s):

Dominik Péus ◽

Dominik Straumann ◽

Alexander Huber ◽

Christopher J. Bockisch ◽

Vincent Wettstein

Keyword(s):

Hair Cells ◽

Whole Body ◽

Downbeat Nystagmus ◽

Two Dimensional ◽

Body Rotation ◽

Therapeutic Approaches ◽

Atypical Case ◽

Anterior Semicircular Canal ◽

Head Positions ◽

Peripheral Origin

Downbeat nystagmus (DBN) observed in head-hanging positions, may be of central or peripheral origin. Central DBN in head-hanging positions is mostly due to a disorder of the vestibulo-cerebellum, whereas peripheral DBN is usually attributed to canalolithiasis of an anterior semicircular canal. Here, we describe an atypical case of a patient who, after head trauma, experienced severe and stereotypic vertigo attacks after being placed in various head-hanging positions. Vertigo lasted 10–15 s and was always associated with a robust DBN. The provocation of transient vertigo and DBN, which both showed no decrease upon repetition of maneuvers, depended on the yaw orientation relative to the trunk and the angle of backward pitch. On a motorized, multi-axis turntable, we identified the two-dimensional Helmholtz coordinates of head positions at which vertigo and DBN occurred (y-axis: horizontal, space-fixed; z-axis: vertical, and head-fixed; x-axis: torsional, head-fixed, and unchanged). This two-dimensional area of DBN-associated head positions did not change when whole-body rotations took different paths (e.g., by forwarding pitch) or were executed with different velocities. Moreover, the intensity of DBN was also independent of whole-body rotation paths and velocities. So far, therapeutic approaches with repeated liberation maneuvers and cranial vibrations were not successful. We speculate that vertigo and DBN in this patient are due to macular damage, possibly an unstable otolithic membrane that, in specific orientations relative to gravity, slips into a position causing paroxysmal stimulation or inhibition of macular hair cells.

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