Brain and Nerve最新文献

POEMS syndrome is a multisystem disorder associated with monoclonal plasma cell proliferation and the overproduction of vascular endothelial growth factors. The prognosis of POEMS syndrome has significantly improved owing to anti-myeloma treatments such as thalidomide and autologous stem cell transplantation. Therefore, early diagnosis and appropriate treatment are becoming increasingly important. A thorough and comprehensive evaluation of both systemic symptoms and laboratory abnormalities associated with the disease is essential for early diagnosis. The collaboration between neurology and hematology is indispensable to ensure proper treatment.

Neuromuscular ultrasound has become an integral part of the diagnostic workup of neuromuscular diseases in neurology. Neuromuscular ultrasound can detect nerve enlargement, selective muscle damage, and fasciculation easily and non-invasively, which allows differentiation between auto-immune/inflammatory and degenerative/hereditary diseases. It is significant and essential for all neurologists to master the neuromuscular ultrasound technique.

Sarcoidosis is an idiopathic granulomatous multi-organ disease, primarily affecting the respiratory system, eyes, and skin, with less involvement in peripheral neurons and muscles. Sarcoid peripheral neuropathy encompasses cranial and spinal nerve impairment. Muscle involvement is often asymptomatic and revealed through imaging. Symptomatic muscle involvement is categorized into three clinical types: nodular myopathy, acute myopathy, and chronic myopathy. The identification of noncaseating granulomas in peripheral nerves or muscles, coupled with the exclusion of other diseases, is essential for establishing a definitive diagnosis of sarcoid peripheral neuropathy and myopathy. Sarcoid neuropathy and myopathy are typically managed with high-dose corticosteroids, immunosuppressants, or a combination of both. In recent times, the use of TNF-alpha inhibitors has notably increased. However, these conditions often exhibit resistance to treatment and may necessitate prolonged therapeutic interventions. Therefore, comprehensive examinations should be conducted before considering immunotherapy. Due to the rarity of these conditions, research on manifestation-specific treatments is lacking, and standard treatments for sarcoid neuropathy and myopathy have not been established. Additional treatment options for sarcoid neuropathy and myopathy are expected to become available in the future.

Electrophysiologic testing plays an important role in evaluating peripheral nerve, muscle, and neuromuscular junction diseases, aiding in diagnosis and treatment strategies by offering real-time assessment. Demyelination of peripheral nerves results in increased conduction delay, temporal dispersion, conduction block, and stimulation threshold. The localization or diffusion of these changes is crucial in understanding disease pathogenesis, necessitating stimulation at multiple points along nerve pathways. When axonal degeneration occurs, the amplitude is reduced, with mild conduction delay. Acute axonal degeneration may require 1 week to develop into Wallerian degeneration. During this time, conductivity was preserved in the nerve peripheral to the lesion. When MG or LEMS is suspected, repetitive nerve stimulation tests and single-fiber EMG are valuable for the diagnosis and pathophysiological evaluation. Notably, the latter is highly sensitive but not specific. Needle electromyography (EMG) assists in differentiating between myopathies and neurogenic diseases, and in determining whether the patient is in an acute or chronic stage. Integration of these tests contribute to an accurate diagnosis when considering the presenting symptoms.

Multifocal motor neuropathy (MMN), an acquired chronic progressive immune-mediated motor neuropathy, is characterized by asymmetrical distal upper limb muscle weakness and muscle atrophy without sensory impairment. Differentiation from amyotrophic lateral sclerosis is usually challenging, and electrophysiological studies show multifocal conduction blocks. Immunoglobulin (Ig)M GM1 antibodies are detected in approximately 50% of patients. In contrast to chronic inflammatory demyelinating polyneuropathy, corticosteroids are ineffective for management of MMN, and IVIg is the sole established treatment.

Vasculitic neuropathy is commonly associated with systemic vasculitis, leading to ischemic damage to the peripheral nerves and axonal degeneration. The typical clinical manifestation of vasculitic neuropathy is a sensory-dominant multiple mononeuropathy often accompanied by pain. Although vasculitic neuropathy is caused by various systemic diseases, ANCA-associated vasculitis, secondary systemic vasculitis linked to various collagen diseases, and non-systemic vasculitic neuropathy hold particular significance. A comprehensive understanding of vasculitic neuropathy is crucial for its early diagnosis, contributing to an improved prognosis for this condition.

Muscle biopsy for inflammatory myopathies facilitates the direct observation of muscle pathology at the site of inflammation by obtaining a small amount of tissue for pathological diagnosis. In clinical settings, muscle pathology derived from a muscle biopsy provides information limited to the tissue sampled. Thus, clinical information must supplement this to ascertain whether the obtained muscle pathology aligns with patient clinical presentation of myositis. This paper discusses considerations for effectively utilizing muscle biopsy in diagnosing inflammatory muscle diseases in clinical practice. Additionally, we briefly explore interpreting the pathological findings of myositis obtained from biopsy samples.

AL amyloidosis, derived from amyloidogenic immunoglobulin light chains, is a common type of systemic amyloidosis. Peripheral neuropathy has been identified in 10%-40% of patients with systemic AL amyloidosis. Definitive diagnosis requires tissue biopsies, including skin, fat, and gastrointestinal samples, as well as amyloid typing. Disease-modifying therapies have been shown to improve patient survival and prevent progressive organ dysfunction.

Fisher syndrome is recognized as a variant of Guillain-Barré syndrome, encompassing acute onset immune-mediated neuropathies marked by the classical triad of ataxia, areflexia, and ophthalmoplegia. Generally, Fisher syndrome follows a self-limited course with a good prognosis. Ophthalmoplegia, typically bilateral, progresses to complete external ophthalmoplegia within 1-2 weeks. Ataxia, often very severe, may cause an inability to walk without support despite normal strength. Fisher syndrome is also frequently concomitant with additional clinical features, including ptosis, internal ophthalmoplegia, facial nerve palsy, sensory deficits, and bulbar palsy. The confirmation of an antecedent infection is often established. Among the ganglioside antibodies, anti-GQ1b antibodies exhibit positivity in over 80% of patients. The syndrome manifests in three distinct types: a partial subtype exhibiting only a subset of the triad symptoms, Bickerstaff's brainstem encephalitis marked by impaired consciousness and pyramidal tract signs, and an overlapping subtype with Guillain-Barré syndrome, characterized by weakness in the extremities.

Anti-myelin-associated glycoprotein (MAG) neuropathy, which occurs secondary to immunoglobulin (Ig)M paraproteinemia such as monoclonal gammopathy of undetermined significance, is characterized by slow progression, sensory or sensorimotor disturbances, and ataxia. The estimated prevalence of this neuropathy in Japan is 0.28 per 100,000 population with male preponderance. This neuropathy is diagnosed based on the detection of M protein and anti-MAG antibodies in patients' serum. Nerve conduction studies show prolonged distal latency, and histopathological evaluation of sural nerve biopsies shows widely spaced myelin on electron microscopy. Usually, immunotherapy, including administration of intravenous Ig and corticosteroids, is ineffective, and rituximab is beneficial in approximately 50% of patients. Novel therapies, such as administration of Bruton's tyrosine kinase inhibitors are expected to benefit patients with the MYD88^L265P mutation.