Leveraging a neurotoxin

Botulinum toxin is among the most effective pharmacologic agents accessible to neurologists, but it is also one few resident physicians experience using. Derived from the lethal bacterium, Clostridium botulinum, this neurotoxin can cause flaccid paralysis and death among newborns or these poisonous effects can be tactically harnessed for good. In this week’s BrainWaves episode, Dr. Anh-Thu Vu discusses the therapeutic uses of this bacterial product.

The toxin’s active component is a core protein with a heavy chain that binds to the neuron, and a light chain that cleaves SNARE proteins preventing release of vesicles that contain neurotransmitters. When used therapeutically in our movement disorders clinic, it is administered as intramuscular injections, and the targets and amount used depend on what is being treated. With only 1-10 units used on facial muscles (for disorders like blepharospasm), and 50 or more units on larger muscle groups like the trapezius (for some cases of spasmodic torticollis). Benefits start to take effect over a week and typically last 3-5 months.

Recording with Anh-Thu Vu.

What conditions are amenable to botulinum toxin treatment?

Rendition of a patient with hemifacial spasm.

  • Focal or Segmental Dystonias (e.g., cervical dystonia, “writer’s cramp”)
  • Strabismus
  • Blepharospasm
  • Hemifacial spasm
  • Spastic bladder
  • Hyperhidrosis
  • Sialorrhea
  • Chronic Migraine

It can also help improve quality of life in stroke patients with spasticity, but not necessarily improve function of the affected limb. It can reduce sialorrhea in patients with parkinsonism and ALS, but caution must be exercised to avoid dysphagia. In particularly violent neck tics, it can be helpful in reducing the sensory urge to perform the tic.

For more information on the benefits of botulinum toxin, the toxin serotypes, and the process of chemodenervation, check out the podcast and hear what Dr. Vu has to say.

 

[Jim Siegler]


REFERENCES

  1. Arnon SS, Schechter R, Inglesby T V, et al. Botulinum toxin as a biological weapon: medical and public health management. JAMA. 2001;285(8):1059-1070.
  2. Thenganatt MA, Fahn S. Botulinum toxin for the treatment of movement disorders. Curr Neurol Neurosci Rep. 2012;12(4):399-409. doi:10.1007/s11910-012-0286-3.
  3. Aurora SK, Winner P, Freeman MC, et al. OnabotulinumtoxinA for treatment of chronic migraine: pooled analyses of the 56-week PREEMPT clinical program. Headache. 2011;51(9):1358-1373. doi:10.1111/j.1526-4610.2011.01990.x.
  4. Dauer WT, Burke RE, Greene P, Fahn S. Current concepts on the clinical features, aetiology and management of idiopathic cervical dystonia. Brain. 1998;121 ( Pt 4):547-560.
  5. Karp BI. Botulinum toxin treatment of occupational and focal hand dystonia. Mov Disord. 2004;19 Suppl 8:S116-S119. doi:10.1002/mds.20025.
  6. Elia AE, Filippini G, Calandrella D, Albanese A. Botulinum neurotoxins for post-stroke spasticity in adults: a systematic review. Mov Disord. 2009;24(6):801-812. doi:10.1002/mds.22452.
  7. Naumann M, Dressler D, Hallett M, et al. Evidence-based review and assessment of botulinum neurotoxin for the treatment of secretory disorders. Toxicon. 2013;67:141-152. doi:10.1016/j.toxicon.2012.10.020.
  8. Lotia M, Jankovic J. Botulinum Toxin for the Treatment of Tremor and Tics. Semin Neurol. 2016;36(1):54-63. doi:10.1055/s-0035-1571217.

ACKNOWLEDGEMENTS

Emory Movement Disorders Fellowship Director, Dr. Stewart Factor, and Dr. Hyder Jinnah in their expertise in the area of dystonia.

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