Bickerstaff Brainstem Encephalitis

Bickerstaff's brainstem encephalitis (BBE) is a rare post-infectious neurological disease characterized by the association of external ophthalmoplegia, ataxia, lower limb arreflexia, extensor plantar response and disturbance of consciousness (drowsiness, stupor or coma).

Epidemiology

Prevalence is unknown.

Clinical description

Patients usually present with onset of diplopia and gait disturbance following upper respiratory or gastrointestinal tract infections. The external ophthalmoplegia is progressive (within 4 weeks of onset) and relatively symmetrical. Flaccid symmetrical tetraparesis may also be observed in over half of the patients, together with deep or superficial sensory impairment, facial weakness, bulbar palsy, internal ophthalmoplegia, blepharoptosis and nystagmus. In the acute phase of disease, BBE may be so severe that there is complete ophthalmoplegia, facial diplegia and full paralysis of arms and legs, resembling 'brain-death'.

Etiology

BBE has been reported to occur following infection with several agents including cytomegalovirus, Campylobacter jejuni, and Mycoplasma pneumonie. Although the exact pathological mechanism is not fully understood, BBE is associated with the presence of the antiganglioside antibody, anti-GQ1b.

Diagnostic methods

Diagnosis is based on the clinical findings, patient history, cerebrospinal fluid (CSF) analysis (revealing raised protein levels), detection of anti-GQ1b IgG antibodies (not present in all patients), MRI studies (revealing high-intensity abnormalities in the posterior fossa, white matter or thalami) and neurophysiological examinations (electroencephalogram and electromyography indicative of central nervous system and predominantly axonal involvement).

Differential diagnosis

BBE shows clinical overlap with Miller-Fisher syndrome (MFS; see this term), a cranial nerve variant of Guillain-Barré syndrome (GBS; see this term), as well as with the axonal forms of GBS (acute motor axonal neuropathy and acute motor-sensory axonal neuropathy; see these terms) in patients with limb weakness, leading several authors to suggest that BBE, MFS and GBS represent variable manifestations of the same clinical spectrum. The differential diagnosis in patients with BBE should also include acute disseminated encephalomyelitis (ADEM; see this term), as well as rare post-infectious neurological disorders.

Management and treatment

Management is based on immunotherapy with intravenous immunoglobulin (IVIg) or plasma exchange.

Prognosis

Although the clinical picture is severe, the disease course is generally monophasic with complete remission of symptoms within 6 months in over half of the patients. Other patients may have mild to severe residual findings.