Brachial amyotrophic diplegia, also calledVulpian-Bernhardt Syndrome (VBS), flail arm syndrome, or man-in-barrel syndrome, is a raremotor neuron disease, often considered to be a phenotype or regional variant ofamyotrophic lateral sclerosis.[1] In the first twelve to eighteen months, only a progressive weakness of one or both arms is observed.[2] Within the spectrum of ALS, this subtype has a relatively longer survival time. Because of its distinct symptoms, it was suggested that VBS is a separate entity, different from ALS.
The disease was described first in 1886 by the French neurologistAlfred Vulpian and the German neuropathologistMartin Bernhardt as a progressive weakness of the upper limbs butbulbar muscles unaffected.[3] It is a rare and atypical disease that can only be diagnosed after a significant time has elapsed.[4] A 2015 study found significant differences between ALS and VBS, most importantly the absence of signs ofupper motor neuron compromise in patients with VBS. The study suggested that VBS is a different entity from ALS.[5]
While the cause is usually unknown, it can arise as aparaneoplastic syndrome.[6] There have been case reports linking the condition toSOD1 mutations.[7]
A study of 1,188 ALS cases in London between 1993 and 2007, and 432 in Melbourne, classified cases asflail arm syndrome when in the first 12 months only a weakness of upper limbs was reported.[8] Based on this criterium, 135 cases or 11% were classified asflail arm syndrome. At later stages, weakening of lower limbs and other ALS symptoms were observed. 16 per cent of these flail arm syndrome cases survived more than ten years, the highest of all variants of ALS in the study.
One of the few people with brachial amyotrophic diplegia who has spoken in public about the disease is Sonia Bustamante Dominguez, a Mexican woman who showed the first symptoms in 2012 and was diagnosed in 2016. In 2024 she described her body as a jail.[9]
