Letters

T A Cho, et al. recently presented in New England Journal of Medicine an interesting case of a young male with complaints of oltagia, slurred speech, and ataxia with a final diagnosis of post-infectious cerebellaritis. (N Engl J Med. 26;369(13):1253-61) The authors rightly included Bickerstaff Brainstem Encephalitis (BBE) and other variants of the Anti-GQ1B antibody syndrome in the differential diagnosis. However, the authors state that BBE is characterized by the presence of Anti-GQ1b IgG Antibodies, which is misleading.

BBE is an extremely rare neurological condition classically characterized by a constellation of signs and symptoms including ophthalmoplegia, ataxia, and altered sensorium and is commonly preceded by an upper respiratory tract infection.^1,2 The clearly described absence of ophthalmoplegia and altered sensorium in the case makes BBE an unlikely diagnosis however, it should be noted that BBE has many variants. When the diagnosis is considered, seropositivity for Anti-Gq1B IgG antibodies can help strengthen the likelihood of an accurate diagnosis. However, it should be noted that negative antibody testing does not preclude the diagnosis. In an analysis of 62 cases of BBE with a strict diagnostic criteria of acute symmetrical opthalmoplegia, altered sensorium, and ataxia, anti-Gq1b antibodies were positive in 66% of patients.¹ A study with a larger study population over 500 cases also showed anti-Gq1b seropositivity in approximately 68 percent of patients.³ In a subset of patients with atypical neurological symptoms and/or negative antibody testing there may be a delayed onset in recovery.⁴

In conclusion, new onset ataxia that is preceded by an infectious illness warrants special consideration for BBE, and seropositivity for Anti-GQ1B antibodies can help make the diagnosis but by no means rules out the diagnosis.

Read the “Expert Opinion” from last edition at PracticalNeurology.com:http://bmctoday.net/practicalneurology/ 2013/10/article.asp?f=bickerstaffs-brainstem-encephalitis-arare- variant-of-the-anti-gq1b-antibody-syndrome

1. Odaka M, Yuki N, Yamada M et al. Bickerstaff's brainstem encephalitis: clinical features of 62 cases and a subgroup associated with Guillain-Barre Syndrome. Brain 2003;126:2279–90.
2. Odaka M, Yuki N, Hirata K. Anti-Gq1b IgG antibody syndrome: clinical and immunological range. J Neurology, Neurosurgery, and Psychiatry 2001. 70:50-55.
3. Ito M, Kuwabara K, Odaka M et al. Bickerstaff's brainstem encephalitis and Fisher syndrome form a continuous spectrum: clinical analysis of 581 cases. Journal of Neurology 2008;255:674–82.
4. Koga M Kusunoki S, Kaida K et al. Nationwide survey of patients in Japan with Bickerstaff brainstem encephalitis: epidemiological and clinical characteristics. J Neurology Neurosurgery Psychiatry 2012;83:1210-1215.