Effect of chlorzoxazone in patients with downbeat nystagmus: A pilot trial

Feil, Katharina; Claassen, Jens; Bardins, Stanislavs; Teufel, Julian; Krafczyk, Siegbert; Schneider, Erich; Schniepp, Roman; Jahn, Klaus; Kalla, Roger; Strupp, Michael (2013). Effect of chlorzoxazone in patients with downbeat nystagmus: A pilot trial. Neurology, 81(13), pp. 1152-1158. Lippincott Williams & Wilkins 10.1212/WNL.0b013e3182a55f6d

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Objective: Downbeat nystagmus (DBN) is the most frequent form of acquired persisting fixation nystagmus with different symptoms such as unsteadiness of gait, postural instability, and blurred vision with reduced visual acuity (VA) and oscillopsia. However, different symptomatic therapeutic principles are required, such as 3,4-diaminopyridine and 4-aminopyridine, that effectively suppress DBN. Chlorzoxazone (CHZ) is a nonselective activator of small conductance calcium-activated potassium (SK) channels that modifies the activity of cerebellar Purkinje cells. We evaluated the effects of this agent on DBN in an observational proof-of-concept pilot study.

Methods: Ten patients received CHZ 500 mg 3 times a day for 1 or 2 weeks. Slow-phase velocity of DBN, VA, postural sway, and the drug's side effects were evaluated. Recordings were conducted at baseline, 90 minutes after first administration, and after 1 or 2 weeks.

Results: Mean slow-phase velocity significantly decreased from a baseline of 2.74°/s ± 2.00 to 2.29°/s ± 2.12 (mean ± SD) 90 minutes after first administration and to 2.04°/s ± 2.24 (p < 0.001; post hoc both p = 0.024) after long-term treatment. VA significantly increased and postural sway in posturography showed a tendency to decrease on medication. Fifty percent of patients did not report any side effects. The most common reported side effect was abdominal discomfort and dizziness.

Conclusions: The treatment with the SK-channel activator CHZ is a potentially new therapeutic agent for the symptomatic treatment of DBN.

Classification of evidence: This study provides Class IV evidence that CHZ 500 mg 3 times a day may improve eye movements and visual fixation in patients with DBN.

Item Type:

Journal Article (Original Article)


04 Faculty of Medicine > Department of Head Organs and Neurology (DKNS) > Clinic of Neurology

UniBE Contributor:

Kalla, Roger


600 Technology > 610 Medicine & health




Lippincott Williams & Wilkins




Valentina Rossetti

Date Deposited:

23 Jun 2014 08:58

Last Modified:

13 Dec 2014 17:23

Publisher DOI:






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