New strategy for improving the diagnostic sensitivity of repetitive nerve stimulation in myasthenia gravis.

INTRODUCTION: The diagnostic sensitivity of repetitive nerve stimulation (RNS) in patients with myasthenia gravis (MG) varies as a function of the number of muscles or the choice of muscles studied. METHODS: By exploring 12 muscles bilaterally, we evaluated the global sensitivity of RNS at rest, the sensitivity in different clinical forms, and the sensitivity of different combinations of muscles studied. RESULTS: The global sensitivity of RNS was 82%, and specificity was 100%. The sensitivity in the MG subgroups was as follows: ocular (O) = 67%; oculobulbar (OB) = 86%; and generalized (G) = 89%. The most sensitive muscles were the anconeus in group O, orbicularis oculi (OO) or nasalis in group OB, and the trapezius in group G. Maximum sensitivity was obtained by exploring OO, trapezius, and anconeus bilaterally. CONCLUSIONS: We recommend bilateral exploration of at least 3 muscles, a facial muscle, trapezius, and anconeus. Muscle Nerve 55: 532-538, 2017.

Stroke in a young patient treated by alteplase heralding an acquired thrombotic thrombocytopenic purpura.

BACKGROUND AND PURPOSE: Thrombotic thrombocytopenic purpura (TTP) is a life-threatening multisystem disorder characterized by thrombocytopenia and fluctuating neurological symptoms due to microinfarcts. In rare cases, large cerebral arteries can be occluded. SUMMARY OF THE CASE: We report on a 30-year-old woman with a first-ever acute stroke related to a right proximal MCA M1 occlusion. Platelet count was normal at admission and progressively decreased 6 days after intravenous thrombolysis with the occurrence of a hemolytic anemia with schistocytes. Most biological anomalies reversed after plasma exchange. No hemorrhagic complication occurred. Diagnosis of initial TTP was confirmed by low ADAMTS13 activity and positivity of anti-ADAMTS13 antibody. CONCLUSION: This observation highlights the fact that even if platelet count and hemoglobin rate are normal in the beginning, an acute ischemic stroke in a young patient can be related to TTP. Faced with subsequent thrombopenia, practitioners should be aware of acquired TTP, and, thus, schistocytes, haptoglobin, and LDH assays should be performed. Early diagnosis is paramount to start the life-saving plasma exchanges.

Detection of proximal conduction blocks using a triple stimulation technique improves the early diagnosis of Guillain-Barré syndrome.

OBJECTIVE: Current diagnostic electrophysiological criteria can miss the early stages of Guillain-Barré syndrome (GBS). We evaluated the diagnostic efficiency of the triple stimulation technique (TST) in highlighting proximal conduction blocks (CBs) in patients who do not meet the electrophysiological criteria for GBS. METHODS: All patients with a diagnosis of clinical GBS referred to our center between September 2014 and January 2016 were included in the study. For patients who did not fulfill the electrophysiological criteria of GBS, we performed the TST examination. RESULTS: Among the 44 included patients, 86% fulfilled the electrophysiological criteria of GBS during the initial nerve conduction study (NCS). The six remaining patients had proximal CBs revealed by TST examination. Therefore, a combination of a conventional NCS and the TST allowed 100% of the patients to be electrophysiologically diagnosed. CONCLUSIONS: TST is useful for the diagnosis of GBS in association with NCS, particularly in the early stages of the disease. SIGNIFICANCE: TST is a useful tool for GBS diagnosis at the early stages of the disease.

Motor unit number index (MUNIX) in patients with anti-MAG neuropathy.

OBJECTIVE: To investigate the relationship between Motor Unit Number Index (MUNIX) and functional scales in patients with anti-Myelin Associated Glycoprotein (MAG) neuropathy and to know if MUNIX is modify after rituximab (RTX) therapy. METHODS: 17 patients were enrolled, of whom 6 were prospectively evaluated during one year after RTX treatment. MUNIX technique was assessed in abductor digiti mini (ADM), abductor pollicis brevi (APB) and tibialis anterior (TA) muscles. MUNIX sum score was calculated by adding the results of ADM, APB and TA muscles. RESULTS: MUNIX sum score was correlated with overall neuropathy limitation scale (ONLS) (r=-0.55, p=0.02), grip strength in dominant hand (r=0.63, p=0.01) MRC testing (r=0.71, p<0.001) and CMAP sum score (r=0.71, p=0.001). Twelve months after RTX, four patients improved their disability measured on the ONLS score, five patients had improved MUNIX sum score with a median increase of 37% compared to initial evaluation. CONCLUSIONS: MUNIX is related to motor impairment and disability in anti-MAG neuropathy and MUNIX is modified after immunosuppressive treatment. SIGNIFICANCE: Considering its advantages, MUNIX may be a suitable test to evaluate anti-MAG neuropathy in clinical trials.

Motor unit number index (MUNIX): Is it relevant in chronic inflammatory demyelinating polyradiculoneuropathy (CIDP)?

OBJECTIVE: To determine the test-retest reliability of motor unit number index (MUNIX) technique and to explore if the MUNIX sumscore could be related with disability in chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). METHODS: The MUNIX technique was unilaterally assessed in the abductor digiti mini (ADM), the abductor pollicis brevi (APB) and the tibialis anterior (TA) muscles two different times by two blinded examiners. The MUNIX sumscore was calculated by adding the results of the ADM, APB and TA muscles. RESULTS: 14 CIDP patients were enrolled. The intraclass correlation coefficient (ICC) was great for inter and intra variability for ADM muscles (0.8 and 0.81), TA muscles (0.86 and 0.89) and MUNIX sumscore (0.76 and 0.83). The MUNIX sumscores from the first and second evaluations were strongly correlated (r=0.83, p<0.001). The MUNIX sumscore was significantly correlated with MRC testing (r=0.71, p<0.01), overall neuropathy limitation scale (ONLS) (r=-0.70, p<0.001), rasch-built overall disability scale (R-ODS) (r=0.71, p<0.001). CONCLUSIONS: The MUNIX technique has a good reproducibility and the MUNIX sumscore is related to the disability. SIGNIFICANCE: The MUNIX technique estimates the axonal loss and the number of functional motor units. The MUNIX sumscore may be a good instrument to evaluate the CIDP patients during their follow-up.

Beyond the lesion: the epileptogenic networks around cavernous angiomas.

The relationship between epileptogenic lesions and the extension of epileptogenicity is a major challenge in presurgical evaluation of drug resistant epilepsies. In this study, we aimed at quantifying the epileptogenic properties of brain structures explored by depth electrodes in patients investigated by stereoelectroencephalography (SEEG) and suffering from focal drug-resistant epilepsy associated with cavernous angioma (CA). Epileptogenicity of the perilesional region and distant brain areas was calculated according to the "epileptogenicity index" (EI), a technique that allows mathematical quantification of rapid discharges at seizure onset taking into account the time at which the discharge occurs. Thirteen seizures from 6 patients were studied. Localization of the cavernoma was the frontal lobe (two cases), the temporal lobe (three cases) or the anterior insula (one case). Visual inspection of the ictal discharge showed that in the majority of cases (5/6) the perilesional region was either not involved or involved with other distant sites. Using EI quantification, complex patterns of epileptogenicity were observed in five patients. A large number of brain regions out of the lesional region disclosed higher values than the lesion site. Mean values in the perilesional region and in the extralesional sites were not significantly different (p=0.34). Complex organization of the epileptogenic zone may be found in drug-resistant CA associated epilepsy. Thus, this result should be borne in mind when patients with CA and drug resistant epilepsy are investigated. If there is a suspicion of a larger epileptogenic zone than the lesion, intra-cerebral exploration by SEEG may be required before surgery that may be guided by the definition of the EZ.