Neuromyotonia in association with systemic sclerosis

Neuromyotonia: a skin-deep problem

A 45-year-old woman was evaluated for right-sided hemicorporal scar-like skin lesions on her arm and thoracic and inguinal areas that appeared shortly after reduction mammoplasty. Five years later, she developed spontaneous cramps and involuntary abnormal, painful, twitching movements in the same areas. With time, the cramps worsened and disabled the patient. The use of her right arm triggered contractures of muscles and abnormal movements. A diagnosis of neuromyotonia (NMT) was established on the basis of clinical findings and on electromyographic findings of a burst of high-frequency motor unit potentials recorded in the right triceps in the area of skin lesions. The results of medullary, encephalic MRI as well as a comprehensive metabolic panel were normal. She was positive for antinuclear antibodies without specificity. Neither antineural antibodies nor antivoltage-gated potassium channel complex antibodies (specifically, leucine-rich glioma inactivated protein 1 and contactin-associated protein-like-2) were detected. Her skin lesions were diagnosed as morphea. Two combined strategies of treatment were initiated: antiepileptic drugs for NMT and corticosteroids and methotrexate for morphea. NMT is a rare, debilitating neurological complication of morphea.

Epidemiology and treatment of peripheral neuropathy in systemic sclerosis

OBJECTIVE

The epidemiology and treatment of peripheral neuropathy in systemic sclerosis (SSc) is poorly understood. The objectives of this study were to evaluate the incidence, prevalence, risk factors, and treatments of peripheral neuropathy in SSc.

METHODS

A systematic review of Medline, Embase and CINAHL databases for literature reporting peripheral neuropathy in SSc was performed. Studies evaluating incidence, prevalence, risk factors, and treatments were synthesized. Meta-analysis using a random effects model was used to evaluate the prevalence of peripheral neuropathy.

RESULTS

113 studies reported 949 subjects with at least one type of peripheral neuropathy out of 2143 SSc patients studied. The mean age was 48.5 years. The mean time between SSc onset and detection of peripheral neuropathy was 8.85 years. The pooled prevalence of neuropathy was 27.4% (95%CI 22.4% - 32.7%). Risk factors for peripheral neuropathy in SSc included advanced diffuse disease, anticentromere antibodies, calcinosis cutis, ischemia of the vasa nervosum, iron deficiency anemia, metoclopramide, pembrolizumab, silicosis and uremia. There were 73 subjects with successful treatments (n=36 restoring sensation, n=37 restoring motor or sensorimotor function). Treatments included decompression surgery, prednisone, cyclophosphamide, carbamazepine, transcutaneous electrical nerve stimulation, tricyclic antidepressants and IVIG.

CONCLUSION

All-cause peripheral neuropathy is not uncommon in SSc. Compression neuropathies can be treated with decompression surgery. Observational data reporting immunosuppressive and anticonvulsants to treat peripheral neuropathy in SSc is limited and conflicting. This data provides the signal of effect to justify RCT to evaluate the efficacy of these interventions.

Isaacs' syndrome in a patient with dermatomyositis: case report and review of the literature

This is a case report of Isaacs' syndrome in dermatomyositis. The patient presented with proximal muscle weakness, rash, elevated muscle enzyme, myopathic electromyograph and typical muscle biopsy. Ultimately he developed typical symptoms of Isaacs' syndrome which is an autoimmune channelopathy from voltage gated potassium channel antibody (anti-VGKC) leading to dysfunction of axonal discharge at neuromuscular junctions. It shares some similar characteristics with dermatomyositis such as autoimmunity, its association with malignancy and the response to treatment.