E-Pearls of the Week: Tonic Spasms

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Brought to you by the Residents & Fellows Section of Neurology®.

June 17, 2013

Paroxysmal attacks of dysarthria, ataxia, paresthesias, falls, and muscle spasms have been described in central demyelinating disorders, including multiple sclerosis (MS). While these symptoms mimic those of an acute MS exacerbation, they are transient and fleeting. Paroxysmal dystonia, also called tonic spasms, are the most common paroxysmal movement disorders in MS. They are characterized by brief, stereotyped often painful unilateral muscle contractions lasting 30 seconds - 3 minutes (1). Patients retain awareness and electroencephalographic evaluation excludes seizure. Attacks are classically precipitated by hyperventilation. Ectopic or ephaptic transmission along damaged axons has been commonly implicated but the underlying pathophysiology is debated. Response to carbamazepine is dramatic. Other antiepileptics, acetazolamide, and even botulinum neurotoxin may be useful adjuncts (2).


  1. Rose MR, Ball JA, Thompson PD. Magnetic resonance imaging in tonic spasms of multiple sclerosis. J Neurol 1993;241:115-117. 
  2. Restivo DA, Tinazzi M, Patti F, Palmeri A, Maimone D. Botulinum toxin treatment of painful tonic spasms in multiple sclerosis. Neurology 2003;61:719-720.

Submitted by Roy Strowd, M.D. Resident Physician, Wake Forest School of Medicine, Winston Salem, NC.

Dr. Strowd is a member of the Resident and Fellow Section of Neurology.

For more clinical pearls and other articles of interest to neurology trainees, visit the Neurology Residents & Fellows page.  Listen to this week's Neurology Podcast.


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