Rapid eye movement (REM) sleep behavior disorder (RBD) is a parasomnia characterized by dream enactment behavior during REM sleep. It has been demonstrated that patients with idiopathic RBD are at a significantly increased risk of developing one of the α-synucleinopathies later in life, and this is called “phenoconversion”. Although some physicians argue against disclosing information that could cause patients psychological stress, the patients also have a “right to know” about their own disease. Therefore, determining when and how to disclose this information, in addition to appropriate follow-up, is important. Clonazepam is the first choice of treatment for RBD associated with α-synucleinopathies. Since RBD is one of the premotor symptoms of α-synucleinopathies, and enables its early diagnosis, a combination of RBD and other examinations may contribute to the realization of a disease-modifying therapy. It is hoped that the early establishment of biomarkers could help predict the phenoconversion from RBD to α-synucleinopathies.

The patient was a 36-year-old man. His initial symptom was bilateral thigh and calf pain. When he developed ulcerative colitis in the following year, he also noticed wasting of the calf muscles. The clinical feature is similar to gastrocnemius myalgia syndrome, although the left upper limb was also involved. A high-intensity lesion in the left calf and soleus muscles was observed on MRI, which was lead to the diagnosis of non-granulomatous myositis with infiltration of CD68-positive cells based on muscle biopsy. After steroids were administered, his pain subsided. Evaluation with needle EMG, MRI, and muscle biopsy is important when muscle pain accompanies inflammatory bowel disease.

A 33 year-old woman presented with intentional incontinence, motor aphasia, supranuclear gaze palsy, and spasticity after parotitis. Brain magnetic resonance images (MRI) showed abnormal signaling in long corticospinal tract involving internal capsules and cerebral peduncles, middle cerebellar peduncle, and frontal subcortical white matter lesions. She had a long history of dry eye and mouth. Immunoserological study showed that she was positive for anti-SS-A, aquaporin 4 (AQP4), and AQP5 antibodies. She clinically showed not only Sjögren’s syndrome but also neuromyelitis optica spectrum disorder (NMOSD) without optic neuritis or myelitis. She responded to steroid followed by plasma exchange dramatically. Thereafter, the relapse of brain lesion was once detected while tapering of steroid, but her symptoms have been stable for several years after administration of immunosuppressant. This case suggested that salivary gland inflammation might be associated with the pathogenesis of NMOSD.

A 45-year-old man presented to us due to slowly progressive muscle weakness and sensory disturbances in his lower limbs since his 40’s. He reported multiple episodes of exercise-induced severe muscle fatigue and brown urine in his childhood, which disappeared by age 20. A nerve conduction study showed peripheral axonal neuropathy and then Charcot-Marie-Tooth disease (CMT) was considered as the most likely diagnosis; however, exome sequencing failed to identify a mutation in the known genes of CMTs. Since age 55, he recurrently developed severe rhabdomyolysis that required hospitalization. On suspicion of lipid metabolism disorders, we performed serum acylcarnitine analysis, and which revealed mildly elevated long-chain fatty acids. We re-examined variants obtained via exome sequencing and found a mutation in HADHB. Mitochondrial trifunctional protein (MTP) deficiency is a rare autosomal recessive disorder of mitochondrial fatty acid beta-oxidation caused by HADHA or HADHB mutation. It can be a life-threatening multiorgan disorder with early infantile onset, but it can also present in childhood or adolescence with peripheral neuropathy and recurrent rhabdomyolysis. This case of adult-diagnosed MTP deficiency was characterized by slowly progressive peripheral neuropathy masquerading CMT in addition to muscular symptoms. MTP deficiency should be considered in patients with the combination of peripheral neuropathy and recurrent rhabdomyolysis.

Pediatric multiple sclerosis accompanied by a tumefactive demyelinating lesion (TDL) is extremely rare. Because it is very difficult to distinguish TDLs from neoplasms, invasive brain biopsies are required for a definitive diagnosis. MR spectroscopy (MRS) without brain biopsy was recently shown diagnostic in some patients with TDLs, based on the elevation of glutamate/glutamine peaks. This report describes the clinical course of a 9-year-old girl with multiple sclerosis following a TDL and discusses the usefulness of MRS and brain biopsies to diagnose TDLs.