Clinical and Electrophysiological Characterization of Myokymia and Neuromyotonia in Jack Russell Terriers

Abstract

Background: Generalized myokymia and neuromyotonia (M/NM) in Jack Russell Terriers (JRTs) is related to peripheral nerve hyperexcitability syndrome in humans, a symptom complex resulting from diverse etiologies.Objective: Clinical and electrodiagnostic evaluation is used to narrow the list of possible etiological diagnoses in JRTs with M/NM.Animals: Nine healthy JRTs and 8 affected JRTs. Methods: A prospective study was conducted comparing clinical and electrophysiological characteristics in 8 JRTs affected by M/NM with 9 healthy JRT controls.Results: All affected dogs except 1 had clinical signs typical of hereditary ataxia (HA). In 6 dogs, neuromyotonic discharges were recorded during electromyogram. Motor nerve conduction studies showed an axonal neuropathy in only 1 affected dog. Compared with controls, brainstem auditory-evoked potentials (BAEP) showed prolonged latencies (P o .05) accompanied by the disappearance of wave components in 3 dogs. Onset latencies of tibial sensory-evoked potentials (SEP) recorded at the lumbar intervertebral level were delayed in the affected group (P o .001). The BAEP and SEP results of the only neuromyotonic dog without ataxia were normal.Conclusions and Clinical Importance: The BAEP and spinal SEP abnormalities observed in JRTs with M/NM were associated with the presence of HA. Therefore, these electrophysiological findings presumably arise from the neurodegenerative changes characterizing HA and do not directly elucidate the pathogenesis of M/NM. An underlying neuronal ion channel dysfunction is thought to be the cause of M/NM in JRTs.

Neuromyotonia in a dachshund with clinical and electrophysiological signs of spinocerebellar ataxia

“…In the following case report, a young dachshund with early‐onset ataxia and neuromyotonia is presented. The clinical and electrophysiological findings of the dachshund presented here show a striking resemblance to the results previously reported in Jack Russell terriers with hereditary ataxia and neuromyotonia (Vanhaesebrouck and others 2010b, Bhatti and others, in press).…”

Neurophysiological assessment of spinal cord injuries in dogs using somatosensory and motor evoked potentials

“…Neurophysiological tests have been employed to record SSEPs [5, 6] and MEPs in healthy animals [7–10] and in cases of cervical spondylomyelopathy [11, 12], intervertebral disk disease [13], lumbosacral stenosis [14], hereditary diseases [15, 16] and traumatic injuries [17]. Their use in evaluation of responses to regenerative therapy [18] and in intraoperative monitoring during cervical spinal surgery [19] has also been reported.…”

“…Several anesthetic protocols have been described in veterinary medicine. The use of drugs such as xylazine and dexamedetomidine, midazolam, sufentanil [5, 12, 37–39], ketamine, methohexital and isoflurane [37, 40] has been reported; anesthetic induction and maintenance through constant rate infusion of propofol [15, 35] has also been proposed. While MEPs can be obtained via transcranial magnetic stimulation in sedated patients, strong contraction of masticatory muscles induced by electrical stimulation dictates the need for general anesthesia and the use of protectors to prevent tongue laceration when this technique is employed.…”

“…More investigation and standardization should be determinant for better and more trustable results, and more information extracted from human medicine should be of great benefit to application in animals. SSEPs and MEPs have been used alone or in combination to complement neurological examination, as well as for disease characterization and functional classification of spinal cord injuries [15–17, 20, 26, 31, 37, 40–42]. Several aspects need to be further investigated and defined before results can be compared between studies.…”

A Novel Movement Disorder in Related Male Labrador Retrievers Characterized by Extreme Generalized Muscular Stiffness

“…In dogs, sustained involuntary skeletal muscle contraction leading to muscle stiffness can originate from the muscles (eg, myotonia 1 ), the peripheral nervous system (eg, cramps 2 or neuromyotonia 3 ), or the central nervous system (CNS) (eg, tetanus, myoclonus or movement disorders such as dystonia 4 ). In all of these syndromes, the electromyogram (EMG) shows abnormal electrical muscle discharges.…”