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Objectives Neurogenic muscle hypertrophy (NMH) is a rare condition characterized by focal muscle hypertrophy caused by chronic partial nervous injury. Given its infrequency, underlying mechanisms remain poorly understood. Inspired by two clinical cases, we conducted a systematic review to gain insights into the different aspects of NMH. Methods We systematically searched online databases up until May 30, 2023, for reports of muscle hypertrophy attributed to acquired neurogenic factors. We conducted an exploratory analysis to identify commonly associated features. We also report two representative clinical cases. Results Our search identified 63 reports, describing 93 NMH cases, to which we added our two cases. NMH predominantly affects patients with compressive radiculopathy (68.4%), negligible muscular weakness (93.3%), and a chronic increase in muscle bulk. A striking finding in most neurophysiological studies (60.0%) is profuse spontaneous discharges, often hindering the analysis of voluntary traces. Some patients exhibited features consistent with more significant muscle damage, including higher creatine phosphokinase levels, muscle pain, and inflammatory muscle infiltration. These patients are sometimes referred to in literature as “focal myositis.” Treatment encompassed corticosteroid, Botulinum Toxin A, decompressive surgery, antiepileptic medications, and nerve blocks, demonstrating varying degrees of efficacy. Botulinum Toxin A yielded the most favorable response in terms of reducing spontaneous discharges. Interpretation This systematic review aims to provide a clear description and categorization of this uncommon presentation of an often‐overlooked neurological disorder. Though questions remain about the underlying mechanism, evidence suggests that aberrant fiber overstimulation along with increased workload that promotes focal damage may result in muscle hypertrophy. This may serve as a guide for therapeutic interventions.

Background and purpose This study was undertaken to highlight neonatal Fc receptor inhibition (efgartigimod) as a valuable therapeutic option for patients with refractory seronegative myasthenia gravis (MG) and to emphasize the concept that seronegative MG is greatly constrained by the limitations of currently available diagnostic methods and therapeutic measures. Methods We describe the first refractory, generalized MG (gMG) patient successfully treated with efgartigimod after testing negative on standard autoantibody detection tests. Results Our patient presented with severe fluctuating bulbar and generalized weakness, resulting in multiple myasthenic crises requiring intubation. After a 28‐year medical history of multiple failed lines of treatment, our patient was started on efgartigimod. Over five treatment cycles, a definite improvement in her clinical condition was observed (Myasthenia Gravis Foundation of America class: IIIb to IIb; MG‐Activities of Daily Living score: 11 to 0; MG‐Quality of Life 15 score: 30 to 0; Quantitative MG score: 28 to 6). Standard autoantibody detection tests failed to detect known pathogenic autoantibodies, but cell‐based assay (CBA) identified autoantibodies against clustered adult acetylcholine receptor (AChR). Conclusions In light of recent approvals of efgartigimod by the European Medicines Agency and US Food and Drug Administration exclusively for AChR‐positive gMG forms, our case highlights evidence suggesting that such an approach might be shortsighted and could limit therapeutic options for patients with refractory seronegative gMG. Additionally, introducing more sensitive analytical techniques, exemplified by CBA, may help bridge the gap between seronegative and seropositive patients. This represents an urgent unmet need for gMG patients, as the antibody profile dramatically influences the therapeutic approach.

Controlling posture, i.e., governing the ensemble of involuntary muscular activities that manage body equilibrium, represents a demanding function in which the cerebellum plays a key role. Postural activities are particularly important during gait initiation when passing from quiet standing to locomotion. Indeed, several studies used such motor task for evaluating pathological conditions, including cerebellar disorders. The linkage between cerebellum maturation and the development of postural control has received less attention. Therefore, we evaluated postural control during quiet standing and gait initiation in children affected by a slow progressive generalized cerebellar atrophy (SlowP) or non-progressive vermian hypoplasia (Joubert syndrome, NonP), compared to that of healthy children (H). Despite the similar clinical evaluation of motor impairments in NonP and SlowP, only SlowP showed a less stable quiet standing and a shorter and slower first step than H. Moreover, a descriptive analysis of lower limb and back muscle activities suggested a more severe timing disruption in SlowP. Such differences might stem from the extent of cerebellar damage. However, literature reports that during childhood, neural plasticity of intact brain areas could compensate for cerebellar agenesis. We thus proposed that the difference might stem from disease progression, which contrasts the consolidation of compensatory strategies.

ObjectivesTo compare the sensitivity and specificity of the 2021 European Academy of Neurology/Peripheral Nerve Society (EAN/PNS) diagnostic criteria for chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) with those of the 2010 European Federation of Neurological Societies/Peripheral Nerve Society (EFNS/PNS).MethodsSensitivity and specificity of the two sets of criteria were evaluated in 330 patients with CIDP and 166 axonal peripheral neuropathy controls. Comparison of the utility of nerve conduction studies with different number of nerves examined and of the sensitivity and specificity of the two criteria in typical CIDP and its variants were assessed.ResultsEFNS/PNS criteria had a sensitivity of 92% for possible CIDP and 85% for probable/definite CIDP, while the EAN/PNS criteria had a sensitivity of 83% for possible CIDP and 74% for CIDP. Using supportive criteria, the sensitivity of the EAN/PNS criteria for possible CIDP increased to 85% and that of CIDP to 77%, remaining lower than that of the EFNS/PNS criteria. Specificity of the EFNS/PNS criteria was 68% for possible CIDP and 84% for probable/definite CIDP, while the EAN/PNS criteria had a specificity of 88% for possible CIDP and 98% for CIDP. More extended studies increased the sensitivity of both sets of criteria by 4%–7% but reduced their specificity by 2%–3%. The EFNS/PNS criteria were more sensitive for the diagnosis of typical CIDP while the EAN/PNS criteria were more specific for the diagnosis of distal and sensory CIDP.ConclusionsIn our population, the EAN/PNS criteria were more specific but less sensitive than the EFNS/PNS criteria. With the EAN/PNS criteria, more extended nerve conduction studies are recommended to obtain an acceptable sensitivity while maintaining a high specificity.

This study aimed to assess the diagnostic criteria, ancillary investigations and treatment response using real-life data in multifocal motor neuropathy (MMN) patients. Clinical and laboratory data were collected from 110 patients enrolled in the Italian MMN database through a structured questionnaire. Twenty-six patients were excluded due to the unavailability of nerve conduction studies or the presence of clinical signs and symptoms and electrodiagnostic abnormalities inconsistent with the MMN diagnosis. Analyses were conducted on 73 patients with a confirmed MMN diagnosis and 11 patients who did not meet the diagnostic criteria. The European Federation of Neurological Societies/Peripheral Nerve Society (EFNS/PNS) diagnostic criteria were variably applied. When applying the American Association of Electrodiagnostic Medicine criteria, an additional 17% of patients fulfilled the criteria for probable/definite diagnosis whilst a further 9.5% missed the diagnosis. In 17% of the patients only compound muscle action potential amplitude, but not area, was measured and subsequently recorded in the database by the treating physician. Additional investigations, including anti-GM1 immunoglobulin M antibodies, cerebrospinal fluid analysis, nerve ultrasound and magnetic resonance imaging, supported the diagnosis in 46%-83% of the patients. Anti-GM1 immunoglobulin M antibodies and nerve ultrasound demonstrated the highest sensitivity. Additional tests were frequently performed outside the EFNS/PNS guideline recommendations. This study provides insights into the real-world diagnostic and management strategies for MMN, highlighting the challenges in applying diagnostic criteria.

BackgroundTo assess the ability of the 2021 European Academy of Neurology/Peripheral Nerve Society (EAN/PNS) clinical criteria for chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) to include within their classification the whole spectrum of clinical heterogeneity of the disease and to define the clinical characteristics of the unclassifiable clinical forms.MethodsThe 2021 EAN/PNS clinical criteria for CIDP were applied to 329 patients fulfilling the electrodiagnostic (and in some cases also the supportive) criteria for the diagnosis of CIDP. Clinical characteristics were reviewed for each patient not strictly fulfilling the clinical criteria (‘unclassifiable’).ResultsAt study inclusion, 124 (37.5%) patients had an unclassifiable clinical presentation, including 110 (89%) with a typical CIDP-like clinical phenotype in whom some segments of the four limbs were unaffected by weakness (‘incomplete typical CIDP’), 10 (8%) with a mild distal, symmetric, sensory or sensorimotor polyneuropathy confined to the lower limbs with cranial nerve involvement (‘cranial nerve predominant CIDP’) and 4 (1%) with a symmetric sensorimotor polyneuropathy limited to the proximal and distal areas of the lower limbs (‘paraparetic CIDP’). Eighty-one (65%) patients maintained an unclassifiable presentation during the entire disease follow-up while 13 patients progressed to typical CIDP. Patients with the unclassifiable clinical forms compared with patients with typical CIDP had a milder form of CIDP, while there was no difference in the distribution patterns of demyelination.ConclusionsA proportion of patients with CIDP do not strictly fulfil the 2021 EAN/PNS clinical criteria for diagnosis. These unclassifiable clinical phenotypes may pose diagnostic challenges and thus deserve more attention in clinical practice and research.

Background and purpose There are different criteria for the diagnosis of different variants of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). The 2021 European Academy of Neurology/Peripheral Nerve Society (EAN/PNS) guidelines provide specific clinical criteria for each CIDP variant even if their therapeutical impact has not been investigated. Methods We applied the clinical criteria for CIDP variants of the 2021 EAN/PNS guidelines to 369 patients included in the Italian CIDP database who fulfilled the 2021 EAN/PNS electrodiagnostic criteria for CIDP. Results According to the 2021 EAN/PNS clinical criteria, 245 patients achieved a clinical diagnosis of typical CIDP or CIDP variant (66%). We identified 106 patients with typical CIDP (29%), 62 distal CIDP (17%), 28 multifocal or focal CIDP (7%), four sensory CIDP (1%), 27 sensory‐predominant CIDP (7%), 10 motor CIDP (3%), and eight motor‐predominant CIDP (2%). Patients with multifocal, distal, and sensory CIDP had milder impairment and symptoms. Patients with multifocal CIDP had less frequently reduced conduction velocity and prolonged F‐wave latency and had lower levels of cerebrospinal fluid protein. Patients with distal CIDP more frequently had reduced distal compound muscle action potentials. Patients with motor CIDP did not improve after steroid therapy, whereas those with motor‐predominant CIDP did. None of the patients with sensory CIDP responded to steroids, whereas most of those with sensory‐predominant CIDP did. Conclusions The 2021 EAN/PNS criteria for CIDP allow a better characterization of CIDP variants, permitting their distinction from typical CIDP and more appropriate treatment for patients.