Introduction

• Myokymia refers to the presence of focal or generalized continuous muscle twitching, often exhibiting as an undulating vermiform movement of the overlying skin due to the contraction of small bands of muscle fibers.
• Neuromyotonia is characterized by a combination of myokymia, muscle stiffness/cramp (and sometime collapse) and impaired muscle relaxation.
• Both myokymia and neuromyotonia persist during sleep and under anesthesia.
• Axonal voltage gated potassium channel abnormalities may be responsible for these clinical signs.
• Focal myokymia is generally caused by a structural lesion of the corresponding Lower Motor Neuron (LMN).
• Diagnosis is made by electromyography (EMG) and investigations for possible underlying cause.
• Symptomatic treatment (membrane stabilizing agent) is indicated if it affects quality of life, as well as treatment of underlying cause if one can be found.
• Prognosis is variable depending on severity of clinical signs.

Neuroanatomical basis and pathophysiology

Clinical presentation

Diagnosis

Differential diagnosis

Treatment

Prognosis

Further Reading

Publications

Refereed papers

• Recent references from PubMed and VetMedResource.
• Lowrie M, Garosi L (2016) Classification of involuntary movements in dogs: Tremors and twitches. Vet J 214, 109-116 PubMed.
• Rogatko C P, Glass E N, Kent M et al (2016) Use of botulinum toxin type A for the treatment of radiation therapy induced myokymia and neuromyotonia in a dog. J Am Vet Med Assoc 248 (5), 532-537 PubMed.
• Vanhaesebrouck A E, Bhatti S F, Franklin R J et al (2013) Myokymia and neuromyotonia in veterinary medicine: a comparison with peripheral nerve hyperexcitability syndrome in humans. Vet J 197 (2), 153-162 PubMed.
• Bhatti S F, Vanhaesebrouck A E, Van Soens I et al (2011) Myokymia and neuromyotonia in 37 Jack Russell terriers. Vet J 189 (3), 284-288 PubMed.
• Holland C T, Holland J T, Rozmanec M (2010) Unilateral myokymia in a dog with an intracranial meningioma. Aust Vet J 88 (9), 357-361 PubMed.
• Vanhaesebrouck A E, Van Soens I, Poncelet L et al (2010) Clinical and electrophysiological characterization of myokymia and neuromyotonia in Jack Russell Terriers. J Vet Intern Med 24 (4), 882-889 PubMed.
• Van Ham L, Bhatti S, Polis I et al (2004) ‘Continuous muscle fibre activity’ in six dog with episodic myokymia, stiffness and collapse. Vet Rec 155 (24), 769-774 PubMed.