Musculocutaneous neuropathy.

INTRODUCTION: Isolated musculocutaneous neuropathy is uncommon. In this study we aimed to determine its causes and clinical presentation and interpret the electrodiagnostic findings associated with this condition. METHODS: Our investigation was a retrospective review of patients diagnosed with musculocutaneous neuropathy at the Mayo Clinic (Rochester, Minnesota) electromyography (EMG) laboratory between 1997 and 2015. RESULTS: Thirty-two patients with musculocutaneous neuropathy and 5 patients with lateral antebrachial cutaneous neuropathy were identified. The most common cause was acute trauma or surgery (65%). Fourteen percent of the cases were idiopathic and 14% were inflammatory. Pain and sensory disturbance were more common presentations than weakness. Weakness from nerve injury was not noted in 2 patients, suggesting that other muscles may provide adequate elbow flexion/supination. The bilateral absence of lateral antebrachial cutaneous nerve sensory responses suggests an inflammatory cause. DISCUSSION: Musculocutaneous neuropathy usually results from trauma or iatrogenic injury. Nerve conduction studies alone are insufficient to confirm neuropathy, and needle EMG examination should be a routine part of the diagnostic evaluation. Muscle Nerve 58: 726-729, 2018.

Incidence and prevalence of NMOSD in Australia and New Zealand.

OBJECTIVES: We have undertaken a clinic-based survey of neuromyelitis optica spectrum disorders (NMOSDs) in Australia and New Zealand to establish incidence and prevalence across the region and in populations of differing ancestry. BACKGROUND: NMOSD is a recently defined demyelinating disease of the central nervous system (CNS). The incidence and prevalence of NMOSD in Australia and New Zealand has not been established. METHODS: Centres managing patients with demyelinating disease of the CNS across Australia and New Zealand reported patients with clinical and laboratory features that were suspicious for NMOSD. Testing for aquaporin 4 antibodies was undertaken in all suspected cases. From this group, cases were identified who fulfilled the 2015 Wingerchuk diagnostic criteria for NMOSD. A capture-recapture methodology was used to estimate incidence and prevalence, based on additional laboratory identified cases. RESULTS: NMOSD was confirmed in 81/170 (48%) cases referred. Capture-recapture analysis gave an adjusted incidence estimate of 0.37 (95% CI 0.35 to 0.39) per million per year and a prevalence estimate for NMOSD of 0.70 (95% CI 0.61 to 0.78) per 100 000. NMOSD was three times more common in the Asian population (1.57 (95% CI 1.15 to 1.98) per 100 000) compared with the remainder of the population (0.57 (95% CI 0.50 to 0.65) per 100 000). The latitudinal gradient evident in multiple sclerosis was not seen in NMOSD. CONCLUSIONS: NMOSD incidence and prevalence in Australia and New Zealand are comparable with figures from other populations of largely European ancestry. We found NMOSD to be more common in the population with Asian ancestry.

Utility Of diaphragm ultrasound in myopathy.

INTRODUCTION: Ultrasound (US) evaluation of diaphragm thickness and contractility is an effective tool in neurogenic diaphragm dysfunction. There are limited data about the value of this technique in patients with myopathy. METHODS: We performed a retrospective chart review of cases with electromyography (EMG) -confirmed myopathy and real-time US evaluation of the diaphragm. Diaphragm thickness and thickening ratio (maximal inspiration/expiration) were measured. Demographic, imaging, pathology, and genetic data were reviewed, and the clinical diagnosis was recorded. RESULTS: There were 19 eligible cases, of which 14 (73.7%) had abnormal US findings. Mean diaphragm thickness was 0.12 cm (SD 0.10), and the mean thickening ratio was 1.29 (SD 0.35). In all cases with abnormal US evaluation, the thickening ratio was abnormal. There were no cases with abnormal thickness alone. CONCLUSIONS: US examination can detect diaphragm dysfunction in myopathy. It is important to measure both the baseline thickness and thickening ratio to maximize sensitivity. Muscle Nerve 55: 427-429, 2017.

Detecting fasciculations in cranial nerve innervated muscles with ultrasound in amyotrophic lateral sclerosis.

INTRODUCTION: Cranial muscle fasciculations may be difficult to detect in amyotrophic lateral sclerosis (ALS). Ultrasound (US) detection of fasciculations in these muscles may have clinical utility. METHODS: Patients with suspected ALS were prospectively enrolled. Nerve conduction studies, needle electromyography (EMG), and US examination of cranial muscles were performed. Controls were examined by US only. Fasciculations were counted and scored for each muscle after 10 or 30 seconds. RESULTS: There were 84 patients with ALS. Fasciculations were most frequently found in the genioglossus muscle. Overall, detection rates by US and EMG were similar, but US was more likely to detect frequent fasciculations. Fasciculations were rare in controls, seen in 7 of 1,090 (0.6%) muscles. No control had > 5 fasciculations in any muscle. DISCUSSION: Fasciculations were frequently detected in cranial muscles of patients with ALS. US was found to be a sensitive method, and was not impaired by factors such as anxiety and the inability of the patient to relax. Muscle Nerve 56: 1072-1076, 2017.

The risk of iatrogenic pneumothorax after electromyography.

INTRODUCTION: Pneumothorax is a potentially serious complication of electromyography (EMG). Data on the frequency of pneumothorax after EMG are lacking. The purpose of this study was to determine the frequency, timing, and risk factors for iatrogenic pneumothorax after EMG. METHODS: Cases of pneumothorax after EMG were reviewed for clinical, electrophysiological, and radiological data. RESULTS: Of 64,490 EMG studies, 7 patients had an association between the EMG and pneumothorax. All patients were symptomatic and presented within 24 hours of EMG. Sampling of serratus anterior and diaphragm was causative in 1 patient each. In 5 patients, multiple high-risk muscles were sampled. The highest frequency of pneumothorax was observed with examination of serratus anterior (0.445%) and diaphragm (0.149%). CONCLUSIONS: The frequency of symptomatic iatrogenic pneumothorax after EMG appears to be low, and examinations of serratus anterior and diaphragm carry the highest risk. Electromyographers should be aware of the risk of pneumothorax and should counsel patients accordingly.

Response to treatment in NMOSD: the Australasian experience.

BACKGROUND: Neuromyelitis optica spectrum disorder (NMOSD) is associated with significant morbidity and mortality. Several therapies have been recommended for NMOSD and more recently clinical trials have demonstrated efficacy for three monoclonal antibody therapies. We present a retrospective observational study of treatment response in NMOSD. METHODS: This was a retrospective, unblinded, observational study of treatment efficacy for rituximab and traditional immunosuppressive therapy in patients with AQP4 antibody positive NMOSD. Treatment efficacy was assessed using annualised relapse rates (ARR), time to first relapse and expanded disability status scale (EDSS) scores. RESULTS: Complete relapse and treatment data were available for 43/68 (63%) of AQP4 antibody positive NMOSD cases covering 74 episodes of treatment. In a time to first relapse analysis rituximab showed a risk ratio of 0.23 (95% CI 0.08 - 0.65) when compared with no treatment and there was a non-significant reduction in ARR of 35% compared to pre-treatment. ß-interferon (p = 0.0002) and cyclophosphamide (p = 0.0034) were associated with an increased ARR compared to pre-treatment. Rituximab (median 4.0 [range 0.0 - 7.0]; p = 0.042) and traditional immunosuppressive therapy (median 4.0 [range 0.0 - 8.0]; p = 0.016) were associated with a lower final EDSS compared to ß-interferon (median 6.0 [range 4.0 - 7.5]). CONCLUSIONS: These data provide additional support for the use of rituximab in preference to traditional immunosuppressive agents and MS disease modifying therapies as first line treatment of NMOSD.

Smoking increases the risk of progression in multiple sclerosis: A cohort study in Queensland, Australia.

BACKGROUND: Cigarette smoking has been associated with increased risk of progressive multiple sclerosis (MS). The effect of smoking status on risk and timing of disease progression in patients with MS in Queensland, Australia has not been established. METHODS: A clinical cohort of 646 cases (531 females, 115 males) were followed from first clinic attendance to onset of clinically determined progressive disease. Progression risk was analysed with gender, age, age of onset, exposure to disease modifying therapy, and smoking status as covariates in a Cox proportional hazards analysis. RESULTS: There were significantly higher risks of secondary progressive disease in males (Hazard Ratio, HR 1.83, 95% CI: 1.3-2.7) and in ever smokers (HR 1.4, 95% CI: 1.0-2.0). Progressive disease occurred approximately 4years earlier in ever smokers. Smoking did not affect age of onset of primary progressive disease. CONCLUSIONS: Cigarette smoking was associated with earlier onset of progressive disease in this large clinical cohort. For patients with relapsing-remitting disease, smoking cessation should be encouraged.