BACKGROUND: Isaacs\' syndrome, also known as neuromyotonia or peripheral nerve hyperexcitability, is a rare disorder that affects the peripheral nervous system. Clinical findings include cramps, fasciculations, and myokymia; however, there are few reports of dental treatment for trismus.
METHODS: A patient with trismus due to Isaacs\' syndrome experienced swelling and pain in the gingiva surrounding his right lower first molar. He was diagnosed with chronic apical periodontitis by a dentist near his home. However, the patient was informed that dental treatment and medication could not be administered because of the presence of Isaacs\' syndrome, and he visited the Geriatric Dentistry and Perioperative Oral Care Center at Kyushu University Hospital 2 weeks later. The patient\'s painless mouth-opening distance (between incisors) was 20 mm at that time, and medication, including amoxicillin capsules and acetaminophen, was administered because the dental extraction forceps or endodontic instruments were difficult to insert into the oral cavity for treatment. Two months after his initial visit, the patient visited us complaining of pain in the same area. However, he had recently undergone plasmapheresis treatment in neurology to alleviate limited mouth opening and systemic myalgia, resulting in a pain-free mouth-opening distance of approximately 35 mm. During this temporary period in which he had no restriction in mouth opening, we performed tooth extraction and bridge restoration on the mandibular right first molar and created an oral appliance for sleep bruxism.
CONCLUSIONS: Plasmapheresis therapy transiently reduced trismus, rendering dental interventions feasible, albeit temporarily. This case report underscores the importance of close collaboration between neurologists and dentists who encounter similar cases while furnishing valuable insights to inform dental treatment planning.

UNASSIGNED: Peripheric nerve hyperexcitability (PNH) syndromes are a rare, heterogenous group of diseases characterized by continuous muscle overactivity due to spontaneous discharges of the lower motor neurons.
UNASSIGNED: Here we report four patients presented with painful cramps, generalized muscle twitches and lower extremity weakness. All patients had evidence of neuropathy and neuromyotonic discharges on electrodiagnostic studies. Screening for a broad panel of anti-neuronal antibodies proved uncharacterized neuropil antibodies in one patient. Despite extensive serologic and genetic investigations, no definitive etiology was found in our cohort. One out of three patients responded well to immunotherapy. No other diseases including malignancy appeared for 1.5-3 years follow-up duration.
UNASSIGNED: Our case series indicate a putatively high prevalence of neuropathy in PNH and emphasize anti-neuronal antibody positivity and early diagnosis as potential favorable prognostic factors.

UNASSIGNED: Recessive mutations in the gene encoding the histidine triad nucleotide-binding protein 1 (HINT1) are associated with axonal motor-predominant Charcot-Marie-Tooth (CMT) disease with neuromyotonia. A total of 24 HINT1 gene mutations have been reported so far. Some of these cases had mild to moderate elevations of creatinine kinase with no earlier reports of muscle biopsy findings in these cases. In this study, we describe a patient with axonal motor-predominant neuropathy and myopathy with rimmed vacuoles, likely due to a novel HINT1 gene mutation.
UNASSIGNED: A 35-year-old African American man presented with insidious onset and progressive symmetric distal leg weakness followed by hand muscle atrophy and weakness since the age of 25. He had no muscle cramps or sensory complaints. His 38-year-old brother developed similar symptoms beginning in his early 30 s. On neurologic examination, the patient had distal weakness and atrophy in all limbs, claw hands, pes cavus, absent Achilles reflexes, and normal sensory examination. Electrodiagnostic studies revealed absent/reduced compound motor action potential amplitudes distally with normal sensory responses with no neuromyotonia. His sural nerve biopsy showed a chronic non-specific axonal neuropathy, and a biopsy of the tibialis anterior muscle demonstrated myopathic features and several muscle fibers harboring rimmed vacuoles without inflammation in addition to chronic denervation changes. A homozygous variant, p.I63N (c.188T > A), in the HINT1 gene was found in both brothers.
UNASSIGNED: We describe a novel, likely pathogenic, HINT1 pI63N (c.188T > A) homozygous variant associated with hereditary axonal motor-predominant neuropathy without neuromyotonia in two African American brothers. The presence of rimmed vacuoles on muscle biopsy raises the possibility that mutations in the HINT1 gene may also cause myopathy.

We presented a 23-year-old patient who had experienced neuromyotonia in his left leg. Although he tested negative for anti-LGI1 and anti-CASPR2 antibodies, we diagnosed him with Isaacs syndrome due to myokymic discharges on electromyography and symptoms being relieved by intravenous methylprednisolone (IVMP) and intravenous immunoglobulin (IVIg). IVMP, IVIg, plasma exchange, or cyclosporine treatment did not provide a long-term response; however, rituximab showed long-term improvement. Rituximab should be considered early in the treatment of patients with antibody-negative Isaacs syndrome who are responsive to immunotherapy, including IVMP, IVIg, and plasma exchange, and have long-term symptoms that are hard to control.

暂无摘要。

Recessive loss-of-function mutations in HINT1 are associated with predominantly motor axonal peripheral neuropathy with neuromyotonia. Twenty-four distinct pathogenic variants are reported all over the world, including four confirmed founder variations in Europe and Asia. The majority of patients carry the ancient Slavic founder variant c.110G>C (p.Arg37Pro) that shows a distribution gradient from east to west throughout Europe.
We report a case of HINT1 neuropathy in South America, identified by massive parallel sequencing of a neuropathy gene panel. To investigate the origin of the variant, we performed haplotyping analysis.
A Brazilian adolescent presented with recessive axonal motor neuropathy with asymmetric onset and fasciculations. Neuromyotonia was found on needle electromyography. His parents were not consanguineous and had no European ancestry. The patient carried biallelic pathogenic p.Arg37Pro alterations in the first exon of HINT1. Both alleles were identical by descent and originated from the same ancestral founder allele as reported in Europe.
Our findings expand the geographic distribution of HINT1 neuropathy to South America, where we describe a recognized founder variant in a Brazilian adolescent with no apparent European ancestry. We confirm the association of the hallmark sign of neuromyotonia with the disease.

BACKGROUND: Morvan syndrome (MoS) is a rare autoimmune syndrome associated with antibodies against two kinds of potassium channel proteins, contactin associated protein-like 2 (CASPR2) and leucine-rich glioma inactivated protein 1 (LGI1). MoS patients with only LGI1-antibody seropositivity have rarely been reported. Here, we describe a 64-year-old male MoS patient with only LGI1-antibody seropositivity.
METHODS: A 64-year-old male patient was referred to our hospital due to limb pain, widespread myokymia, insomnia, constipation, and hyperhidrosis for 1 month. The patient was diagnosed with MoS based on the clinical symptoms and positive LGI1-antibody in serum. He was treated with intravenous immunoglobulin (IVIG), intravenous methylprednisolone followed by oral prednisone, and other drugs for symptomatic relief. Several days later, myokymia and insomnia symptoms improved. After 60 days of follow-up, all the drugs had been stopped for 2 weeks, and the patient achieved complete remission without any medical side effects.
CONCLUSIONS: We report the clinical characteristics of a Chinese MoS patient with only LGI1-antibody seropositivity, and further support the view that non-neoplasm MoS patients respond well to immunotherapy.

A 50-year-old male, presented with a two-months history of ascending paresthesias, with continuous twitchings over the body, associated with insomnia. His electromyography (EMG) revealed neuromyotonia and was diagnosed as a case of peripheral nerve hyperexcitability (PNH) syndrome due to Leucin-rich glioma-inactivated 1 (LGI1) antibody. He showed significant improvement with intravenous immunoglobulin and carbamazepine.

暂无摘要。

Isaacs syndrome is rare disorder with peripheral nerve hyperexcitability syndromes with acquired neuromyotonia in childhood. We present a 13-year-old girl with muscle stiffness and neuromyotonia diagnosed Isaac syndrome with spontaneous discharge potentials on motor unit in electromyography and the diagnosis supported by the presence of antinuclear antibodies. A successful treatment was obtained using low-dose carbamazepine. Cause of Isaacs syndrome is unknown, generally thought to be an autoimmune etiology with voltage-gated potassium channelopathy; it sometimes occurs as a paraneoplastic syndrome. Early use of electromyography has critical role in the differential diagnosis with certain muscle disorders and peripheral nerve hyperexcitability syndromes.