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ObjectiveTo examine whether sustained minimal manifestation status (MMS) with complete withdrawal of prednisone is better achieved in thymectomized patients with myasthenia gravis (MG).MethodsThis study is a post hoc analysis of data from a randomized trial of thymectomy in MG (Thymectomy Trial in Non-Thymomatous Myasthenia Gravis Patients Receiving Prednisone Therapy [MGTX]). MGTX was a multicenter, randomized, rater-blinded 3-year trial that was followed by a voluntary 2-year extension for patients with acetylcholine receptor (AChR) antibody-positive MG without thymoma. Patients were randomized 1:1 to thymectomy plus prednisone vs prednisone alone. Participants were age 18-65 years at enrollment with disease duration less than 5 years. All patients received oral prednisone titrated up to 100 mg on alternate days until they achieved MMS, which prompted a standardized prednisone taper as long as MMS was maintained. The achievement rate of sustained MMS (no symptoms of MG for 6 months) with complete withdrawal of prednisone was compared between the thymectomy plus prednisone and prednisone alone groups.ResultsPatients with MG in the thymectomy plus prednisone group achieved sustained MMS with complete withdrawal of prednisone more frequently (64% vs 38%) and quickly compared to the prednisone alone group (median time 30 months vs no median time achieved, p < 0.001) over the 5-year study period. Prednisone-associated adverse symptoms were more frequent in the prednisone alone group and distress level increased with higher doses of prednisone.ConclusionsThymectomy benefits patients with MG by increasing the likelihood of achieving sustained MMS with complete withdrawal of prednisone.Clinicaltrialsgov identifierNCT00294658.Classification of evidenceThis study provides Class II evidence that for patients with generalized MG with AChR antibody, those receiving thymectomy plus prednisone are more likely to attain sustained MMS and complete prednisone withdrawal than those on prednisone alone.

ObjectiveTo develop formal consensus-based guidance for the management of myasthenia gravis (MG).MethodsIn October 2013, the Myasthenia Gravis Foundation of America appointed a Task Force to develop treatment guidance for MG, and a panel of 15 international experts was convened. The RAND/UCLA appropriateness methodology was used to develop consensus guidance statements. Definitions were developed for goals of treatment, minimal manifestations, remission, ocular MG, impending crisis, crisis, and refractory MG. An in-person panel meeting then determined 7 treatment topics to be addressed. Initial guidance statements were developed from literature summaries. Three rounds of anonymous e-mail votes were used to attain consensus on guidance statements modified on the basis of panel input.ResultsGuidance statements were developed for symptomatic and immunosuppressive treatments, IV immunoglobulin and plasma exchange, management of impending and manifest myasthenic crisis, thymectomy, juvenile MG, MG associated with antibodies to muscle-specific tyrosine kinase, and MG in pregnancy.ConclusionThis is an international formal consensus of MG experts intended to be a guide for clinicians caring for patients with MG worldwide.

Many studies have been conducted to observe the sequence of events in recovery from nerve damage. The majority of such studies have been performed in laboratory rats, and only rarely are detailed observations made in human patients recovering from nerve damage. With only minor exceptions, a dead nerve cell cannot be replaced. However, it is possible for new sprouts to arise from neighboring nerve fibers and make new contact with muscle cells deprived of their original nervous input. The sequence of events has been well studied in animals; a computerized method of recording electrical activity in the muscle has now provided an opportunity to observe these events in a human patient undergoing complete recovery from nerve damage. The patient developed paralysis of a facial muscle following surgery on a blood vessel abnormality. No voluntary movement occurred in the muscle for 15 days following the injury. At that time, rapid contractions were detected in some muscle fibers. By 29 days these fibrillations became numerous. These observations indicate that the sprouting of nerve fibers had occurred, and these new fibers were beginning to make contact with the muscle fibers. Computerized calculations based on the electrical activity suggested that these nerve fibers were most dense 37 days after the injury; at this time the fibrillations had already decreased in number. The first indications that normal use of the muscle were returning appeared at this time. By 67 days, the normal function of the muscle was complete. Nevertheless, measurements revealed abnormalities for more than 34 months after the initial injury. This indicates that even after the muscle fibers have been re-innervated, slow processes of reorganization continue to occur in the relation between the muscle and the recovering nerve. (Consumer Summary produced by Reliance Medical Information, Inc.)

Information is provided concerning the new subspecialty certificate in neuromuscular medicine of the American Board of Psychiatry and Neurology and the eligibility requirements for such certification of practicing neurologists and child neurologists. The Accreditation Council for Graduate Medical Education has approved fellowship training in the subspecialty, and it is likely that residents who wish to pursue a career in neuromuscular medicine will select this training option.

Background: Krabbe disease (KD) is associated with marked central and peripheral demyelination and nerve conduction studies (NCS) typically show a mixed sensorimotor demyelinating peripheral neuropathy (PN)., Objectives: To further characterize the PN in a large cohort of patients with KD and to assess the diagnostic sensitivity of NCS in this condition., Methods: The authors report the results of electrodiagnostic studies performed in 27 children with KD, ranging in age from 1 day to 8 years, whose diagnosis was confirmed by leukocyte lysosomal enzyme analysis., Results: Based on age-adjusted normative values, 25 of 27 patients had abnormal NCS (sensitivity > 90%) when at least one motor and one sensory nerve were tested in a lower and an upper extremity. Of the 24 patients with the early infantile form of the disease, 23 had abnormal NCS (sensitivity > 95%). Abnormal sural sensory responses (SNR) (82%), F-wave latencies (FWL) (85%), motor conduction velocities (CV) (82%), and distal motor latencies (DL) (76%) were the most sensitive indices. In the lower extremities the sensitivity of motor CV, FWL, and motor DL was 79%, 79%, and 57%, respectively, while in the upper limbs the corresponding sensitivities were 80%, 87%, and 73%. No conduction block was detected and there was uniform slowing of CV. SNR was unobtainable or abnormal in 82% of patients. The compound muscle action potential amplitudes were within normal limits in >70% of lower limb and >45% of upper limb responses. Marked NCS abnormalities were found in a 1-day-old and two 3-week-old neonates, the youngest patients reported to date. NCS were abnormal in 5/9 children with normal EEG or evoked potentials. The severity of the demyelination on NCS correlated well with the clinical severity of the disease., Conclusions: Peripheral neuropathy occurs very early in Krabbe disease and affects the nerves uniformly. Nerve conduction studies may provide a highly sensitive tool to screen this patient population.

Background: Hematopoietic stem cell transplantation (HSCT) may slow the progression of Krabbe disease (KD) if performed early in the disease. The authors' studies indicate that more than 90% of patients with KD have severe abnormalities in peripheral nerve conduction., Objective: To assess the effect of HSCT on nerve conduction in patients with KD., Methods: The authors performed serial nerve conduction studies (NCS) in 12 patients with KD after HSCT. The average follow-up was 18 months (6 months to 3 years) after HSCT. Pretransplant NCS were not available in two patients; all others (10 of 12) had significant pretransplant abnormalities., Results: After HSCT, previously absent F-waves (1 patient) and sural sensory responses (SNR) (3 patients) were found recordable. All patients continued to have recordable SNR after HSCT, and these became normal in 7 of 12 patients. Distal motor nerve latency became normal in 6 of 17 and motor nerve conduction velocity (CV) in 2 of 17 nerves; F-wave latencies (FWL) improved in 6 of 17 nerves, but did not become normal in any. There was greater improvement in nerve conduction abnormalities if the transplant was performed earlier in life. After an initial improvement, there was subsequent worsening of motor latencies (2 of 12), motor CV (2 of 12), FWL (3 of 12), and SSR (1 of 12), indicating that benefit from HSCT may be temporary., Conclusions: Serial nerve conduction studies are useful in following the course of peripheral neuropathy in Krabbe disease. Hematopoietic stem cell transplantation is followed by improvement in peripheral nerve conduction abnormalities in these patients, suggesting remyelination of the nerves.