SORDD: mutation frequency and phenotype in predominantly axonal Charcot-Marie-Tooth disease of undefined genetic cause.

Pathogenic, biallelic variants in SORD were identified in 2020 as a novel cause for autosomal-recessive Charcot-Marie-Tooth disease (CMT) type 2, an inherited neuropathy. SORD codes for the enzyme sorbitol dehydrogenase. Loss of this enzyme's activity leads to an increase of sorbitol in serum. We retrospectively screened 166 patients with axonal neuropathy (predominantly CMT type 2, but including intermediate form of CMT and distal hereditary motor neuropathy (dHMN)) without identified genetic etiology for SORD mutations at a single large German neuromuscular center. Clinical and electrophysiology exam findings were analyzed for genotype-phenotype correlation. Five patients of the total cohort of 166 patients harbored pathogenic variants in SORD (3%). The homozygous frameshift variant c.757delG (p.Ala253Glnfs*27) was the most common (4/5). One additional case carried this variant on one allele only and an additional pathogenic missense variant c.458C > A (p.Ala153Asp) on the other allele. Age of onset ranged from early infancy to mid-twenties, and phenotypes comprised axonal CMT (4) and dHMN (1). Our findings strengthen the importance of screening for pathogenic variants in SORD, especially in patients with genetically unconfirmed axonal neuropathy, especially CMT type 2 and dHMN.

Treatment of cluster headache attacks with less than 6 mg subcutaneous sumatriptan.

BACKGROUND: Subcutaneous (SQ) sumatriptan 6 mg is effective in the treatment of acute cluster headache attacks. However, patients sometimes benefit from a dose less than 6 mg. OBJECTIVE: Therefore, we designed a prospective open study to evaluate how many patients benefit from a dose less than 6 mg SQ sumatriptan. METHODS: We enrolled 81 consecutive patients with cluster headache and recorded their use of SQ sumatriptan and oxygen. Patients regularly using SQ sumatriptan 6 mg were advised to treat attacks with doses less than 6 mg and with oxygen. Efficacy and side effects of the different treatment options (6 mg, 3 mg, 2 mg, and oxygen) were evaluated. RESULTS: As a result, 74% of the patients using SQ sumatriptan 3 mg showed efficacy and 89% reported efficacy after 2 mg. Seventy-nine percent reported side effects after the use of SQ sumatriptan 6 mg (29% severe side effects). After the use of 2 mg SQ sumatriptan, only 50% of the patients reported side effects, none of these were classified as severe. Patients' preference was 41% for 6 mg sumatriptan, 28% for doses less than 6 mg, and 31% for oxygen. CONCLUSIONS: We conclude that sumatriptan in doses less than 6 mg can be effective in the acute treatment of cluster headache attacks. We suggest that patients should have experience in their individual efficacy of sumatriptan doses less than 6 mg.

Carotid artery dissection in ergotamine abuse.

The case of a 65-year-old male migraine patient with spontaneous internal carotid artery dissection is presented. He had been abusing ergotamine compounds for several years on at least 15 days per month. A possible association between arterial dissection and ergotamine abuse is discussed.