Israel Medical Association Journal

Background: The recreational use of nitrous oxide (N₂O) has increased in recent years with a noticeable surge in the incidence of nitrous oxide-related myeloneuropathy.

Objectives: To raise awareness of increasing myeloneuropathy due to recreational nitrous oxide misuse in Israel.

Methods: We conducted a case series documenting the clinical and investigative features of eight patients presenting with nitrous oxide-induced myeloneuropathy who were admitted to our departments.

Results: Paresthesia was the chief complaint in all patients, with sensory gait ataxia being a common feature, which was often accompanied by Romberg's sign and mild lower limb weakness. Vitamin B12 levels were below the normal range in seven patients, accompanied by elevated homocysteine and methylmalonic acid levels. Magnetic resonance imaging scans revealed hyperintense signals in the dorsal columns of the cervical spine. All patients improved following vitamin B12 injections.

Conclusions: Enhancing awareness, prompting the use of appropriate investigations, and advocating for timely treatment are needed to overcome the risks associated with nitrous oxide misuse.

Carpal tunnel syndrome (CTS) is a collection of symptoms and signs caused by compression of the median nerve as it travels through the carpal tunnel. Symptoms include paresthesia and/or numbness in the median nerve distribution, aching in the thenar eminence, and weakness at later stages. CTS is the most common entrapment neuropathy with a prevalence of 1–5%, and even higher among females, manual workers, and the elderly. Therefore, many patients with signs and symptoms of CTS refer to their primary care physician who should recognize, diagnose, and provide initial treatment.

Background: Myalgic encephalomyelits/chronic fatigue syndrome (ME/CFS) is an acquired disease with symptoms of fatigue and pain. In pathogenesis, the induction of autoantibodies (AAB) against G-protein coupled receptors (GPCR), such as β-adrenergic receptors (β-AdR), has been suspected. GPCR-AAB correlate with symptom severity and autonomic dysfunction in ME/CFS.

Objectives: To describe symptoms and treatment of a patient presenting with infection-triggered ME/CFS demonstrating that levels of β-AdR-AAB underlie modulation over time, correlating with the severity of symptoms.

Methods: At T1 and T2, GPCR-AAB were measured and questionnaires assessing symptom severity were completed. TSHDS-IgM-AAB were tested, and SF density was analyzed via skin probe.

Results: At T2, elevated levels of β-AdR-AAB were found, corresponding with an aggravation of fatigue and pain symptoms. Elevated TSHDS-IgM-AAB were found, which corresponded with reduced fiber density from the skin probe.

Conclusions: The levels of β-AdR-AAB in post-infectious ME/CFS can be modulated. Future studies might target interventions to reduce these AAB.

Background: Fibromyalgia syndrome (FMS) is estimated to affect 2–4% of the general population. While FMS has some known environmental and genetic risk factors, the disorder has no clear etiology. A common coexisting disorder with FMS is small fiber neuropathy (SFN). High levels of serum immunoglobulin M (IgM) binding to trisulfated-heparin-disaccharide (TS-HDS) were recently found to be associated with SFN.

Objectives: To evaluate potential differences in anti-TS-HDS antibody titers in women with FMS compared to healthy controls.

Methods: In this cross-sectional study, we evaluated 51 female participants: 30 with a diagnosis of FMS and 21 healthy controls who had been recruited at the Zabludowicz Center for Autoimmune Diseases, Sheba Medical Center, Israel. All of the participants were older than 18 years of age. Anti-TS-HDS IgM levels were measured in their sera using the enzyme immunoassay technique.

Results: The mean anti-TS-HDS IgM levels were significantly lower in the FMS group, compared with the control group (7.7 ± 5 vs. 13.2 ± 8.6 U/ml, respectively; P = 0.013).

Conclusions: There is a possible association between FMS and anti-TS-HDS IgM. This association might be the missing link for the coexistence of SFN and FMS, but further study should be performed to assess this association and this auto-antibody characteristic.

Background: Brain-derived neurotrophic factor (BDNF) is a neuronal growth factor that is important for the development, maintenance, and repair of the peripheral nervous system. The BDNF gene commonly carries a single nucleotide polymorphism (Val66Met-SNP), which affects the cellular distribution and activity-dependent secretion of BDNF in neuronal cells.

Objectives: To check the association between BDNF Val66Met-SNP as a predisposition that enhances the development of chemotherapy-induced peripheral neuropathy in an Israeli cohort of patients with breast cancer who were treated with paclitaxel.

Methods: Peripheral neuropathy symptoms were assessed and graded at baseline, before beginning treatment, and during the treatment protocol in 35 patients, using the reduced version of the Total Neuropathy Score (TNSr). Allelic discrimination of BDNF polymorphism was determined in the patients' peripheral blood by established polymerase chain reaction and Sanger sequencing.

Results: We found Val/Val in 20 patients (57.14%), Val/Met in 15 patients (42.86%), and Met/Met in none of the patients (0%). Baseline TNSr scores were higher in Met-BDNF patients compared to Val-BDNF patients. The maximal TNSr scores that developed during the follow-up in Met-BDNF patients were higher than in Val-BDNF patients. However, exclusion of patients with pre-existing peripheral neuropathy from the analysis resulted in equivalent maximal TNSr scores in Met-BDNF and Val-BDNF patients.

Conclusions: These observations suggest that BDNF Val66met-SNP has no detectable effect on the peripheral neuropathy that is induced by paclitaxel. The significance of BDNF Val66Met-SNP in pre-existing peripheral neuropathy-related conditions, such as diabetes, should be further investigated.

A 47 year old man presented with a combination of dry mouth and lightheadedness while standing. His medical background was unremarkable except for cigarette smoking and hyperlipidemia. Sjögren’s syndrome was ruled out, and he was referred for evaluation of orthostatic hypotension, which by then included syncopal episodes and injuries. Additional symptoms included dry eyes, constipation, reduced sweating, and erectile dysfunction. After excluding medications and structural cardiac abnormalities as causes of orthostatic hypotension, a clinical autonomic evaluation was performed. The pattern of beat-to-beat blood pressure associated with performance of the Valsalva maneuver, and a low plasma norepinephrine level that did not increase in response to standing, established that the orthostatic hypotension was neurogenic. Treatment with an alpha-adrenoceptor agonist and fludrocortisone yielded partial improvement. After systemic diseases involving autonomic failure were excluded, cardiac sympathetic neuroimaging was performed by ¹²³I-metaliodobenzylguanidine (MIBG) scanning. The normal uptake seen in the heart indicated intact post ganglionic sympathetic innervation. There were no signs of central neurodegeneration or peripheral neuropathy. Because of symptoms and signs of both parasympathetic and sympathetic failure without denervation, an autonomic ganglionopathy was considered. A high titer of antibody to the neuronal nicotinic receptor, which mediates ganglionic neurotransmission, was obtained. The diagnosis of autoimmune autonomic ganglionopathy (AAG) was made, and the management strategy shifted to first lowering the antibody burden by plasma exchanges and then instituting chronic anti-autoimmune treatment with rituximab and a low dose of cortiosteroid. The patient showed remarkable improvement.