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.

Objectives: To describe the phenotypic and genotypic features in five Bulgarian Jewish patients, from different families, with autosomal dominant OPMD.

Methods: We performed clinical follow-up, electrodiagnostic tests and mutation detection. Blood samples were obtained after informed consent and DNA was extracted; measurement of GCG repeats in both PABPN1 alleles and sequencing of OPMD mutations were performed according to standard techniques.

Results: We identified five patients (four females), aged 58 to 71 years, with bilateral ptosis, dysphagia, dysphonia (n=3) and myopathic motor units by electromyography. In all patients we noticed proximal weakness of the upper limbs with winging scapulae in three of them. All cases shared the (GCG)13-(GCG)10 PABPN1 genotype.

Conclusions: OPMD among Bulgarian Jews is produced by a (GCG)13 expansion, identical to the mutation in Uzbek Jews and French Canadians. In addition to the classical neurological and neuro-ophthalmological features, early shoulder girdle weakness is common in Bulgarian Jewish patients; this is an unusual feature during the early stages of OPMD produced by the same mutation in other populations. We suggest that besides the disease-producing GCG expansion, additional ethnicity-related genetic factors may influence the OPMD phenotype. OPMD is a rare disease, and the identification of five affected families in the rather small Bulgarian Jewish community in Israel probably represents a new cluster; future haplotype studies may elucidate whether a founder effect occurred. 

Background: Transthyretin (TTR)-associated familial amyloid polyneuropathy (FAP) is an autosomal dominant multisystem disease with neurological and extra-neurological manifestations. It is caused by various mutations in the TTR gene leading to the formation of insoluble amyloid.

Objectives: To describe the clinical and genetic findings in patients with TTR-associated FAP in Israel.

Methods: We evaluated eight patients clinically and genetically during the years 2006 to 2011.

Results: At onset, all the patients exhibited sensory loss of the lower and upper limbs, five patients experienced muscle pain, and one patient had lower limb weakness. Five patients had autonomic nervous system manifestations, and four demonstrated evidence of amyloid cardiomyopathy. Nerve conduction studies showed sensorimotor axonal neuropathy in all patients. Sural nerve biopsies were obtained in five patients; only three biopsies revealed amyloid deposit. In four patients of Yemenite descent, genetic analysis of the TTR gene demonstrated ser77tyr mutation. One patient of Tunisian descent and one Ashkenazi patient harbored the val30met mutation. One patient of Iranian descent showed val32ala mutation, and another Ashkenazi patient showed phe33leu mutation.

Conclusions: TTR-associated FAP is a progressive and fatal disease that exists in the Israeli population and is unproportionally common among Yemenite Jews. This disease may be under-diagnosed and should be considered in the differential diagnosis of any patient with rapidly progressive neuropathy, especially with autonomic involvement or extra-neural features. The absence of amyloid in nerve biopsy should not rule out the diagnosis.  
 

Background: Myotonic dystrophy type 2 (DM2) is an autosomal dominant, multisystem disorder caused by a CCTG tetranucleotide repeat expansion located in intron 1 of the zinc finger protein 9 gene (ZNF9 gene) on chromosome 3q 21.3.

Objectives: To describe the clinical, electrophysiologic and pathologic findings in patients with myotonic dystrophy 2.

Methods: We evaluated 10 patients genetically, clinically and electrophysiologically during the years 2007 to 2008.

Results: All patients were of Jewish European ancestry. Among affected individuals, eight patients had symptoms of proximal muscle weakness, two had muscle pain, and two exhibited myotonia. On physical examination six patients had severe weakness of hip flexor muscles. Seven individuals underwent cataract surgery, and cardiac involvement was seen in one case. On the initial electromyographic (EMG) examination five patients demonstrated myotonic discharges; repeated studies showed these discharges in nine cases. Six muscle biopsies showed non-specific pathological changes. Seven patients had an affected first-degree relative with either a diagnosed or an undiagnosed muscular disorder, consistent with an autosomal dominant trait.

Conclusions: DM2 may often present with proximal muscle weakness without myotonia. EMG may initially fail to show myotonic discharges, but these discharges may eventually show in most cases on repeated EMG. Thus, DM2 may be underdiagnosed and should be included in the differential diagnosis of adult patients of Jewish European ancestry presenting with proximal lower limb weakness.
 

Background: Ocular hypotony is a common unexplained feature of myotonic dystrophy type 1. Spuriously low applanation tonometric readings can be caused by thin corneas, flat corneal curvature and corneal edema.

Objectives: To determine whether structure abnormalities of the cornea cause spuriously low readings in applanation tonometry.

Methods: We utilized a TMS-2N corneal topographer, a NonconRobo SP-6000 Specular microscope and a Corneo-Gage Plus 1A Pachymeter to examine seven patients with DM1[1] and eight healthy controls. Intraocular pressure, central corneal thickness, and endothelial cell density were measured, and simulated keratometry readings were made. Cornea guttata and irregularity of corneal topography patterns were also sought.

Results: The mean intraocular pressure was 9.86 ± 1.29 mmHg for all patients (intraocular operated and non‑operated eyes) and 12.88 ± 1.89 mmHg for the controls (P = 0.000021, two-tailed t-test). Central corneal thickness was 530.57 ± 35.30 micron for all patients and 535.00 ± 39.62 micron for the controls (P = 0.75, two-tailed t-test). Endothelial cell density was 3164 ± 761 cells/mm² for all patients and 3148 ± 395 cells/mm² for the controls (P = 0.94, two-tailed t-test). Simulated keratometry readings were similar in both groups when the operated eyes were excluded. Cornea guttata and irregularity of corneal topography patterns were also noted in the study group.

Conclusions: Corneal thickness, corneal curvature and corneal hydration were within normal limits and thus were not the cause for the low applanation tonometry reading in DM1. The presence of cornea guttata and irregularity of corneal topography patterns in DM1 warrants further investigation. 

Background: Persistent creatine kinase elevation is occasionally encountered in subjects without any clinical manifestation of a neuromuscular disorder or any condition known to be associated with increased serum CK[1] levels. It is still unresolved whether extensive investigations and specifically a muscle biopsy should be performed in clinically normal individuals with elevated CK levels.

Objective: To study the muscle pathology of patients with asymptomatic or minimally symptomatic hyperCKemia.

Methods: The clinical and laboratory data of patients with persistent hyperCKemia and normal neurologic examination were reviewed and their muscle biopsies evaluated.

Results: The study group included 40 patients aged 7–67 years; the male to female ratio was 3:1. Nineteen patients were completely asymptomatic, 20 had mild non-specific myalgia, and 1 had muscle cramps. Electromyography was performed in 27 patients and showed myopathic changes in 7 (26%). Abnormal muscle biopsy findings (e.g., increased variation in fiber size, increased number of central nuclei and occasional degenerating fibers) were detected in 22 of the 40 patients (55%). No fat or glycogen accumulation was detected. Immunohistochemistry demonstrated abnormal dystrophin staining in 3 patients (8%), resembling the pathologic changes of Becker muscular dystrophy. No abnormal findings were detected on immunohistochemical staining for merosin, dysferlin, caveolin 3, or alpha and gamma sarcoglycans. The EMG[2] findings did not correlate with the pathologic findings.

Conclusions: Abnormal muscle biopsies were found in 55% of patients with asymptomatic or minimally symptomatic hyperCKemia. Specific diagnosis of muscular dystrophy, however, was possible in only 8% of the patients.