Bickerstaff's Brainstem Encephalitis

Bickerstaff's brainstem encephalitis (BBE) is an immune disorder of unknown aetiology. It is characterised by:

• Acute, progressive cranial nerve dysfunction.
• Associated cerebellar ataxia.
• Coma.

There is a clinical continuum between BBE and Fisher's syndrome.^[1]

Bickerstaff reported eight patients who, in addition to acute ophthalmoplegia (diplopia) and ataxia, showed drowsiness, extensor plantar responses or hemisensory loss.^[2]

Epidemiology

• It is very rare and mostly reported in adults; however, cases affecting children have also been reported.^[3]
• Very often it follows an illness, and an association with certain infections, including cytomegalovirus, Campylobacter jejuni, typhoid fever and Mycoplasma pneumoniae, has been documented.^{[4, 5, 6]}

Presentation

• Acute diplopia.
• Ataxia.
• Pyramidal tract paralysis.
• Disturbance of consciousness.
• Headache is common.
• Progressive, symmetrical ophthalmoplegia, ataxia and either disturbance of consciousness or hyperreflexia.
• Facial palsy, extensor plantar reflex, pupillary abnormality, nystagmus and bulbar palsy.
• It may result in apnoea and a reversible brain death picture.

Differential diagnosis^[7]

Multiple sclerosis.
Behçet's disease.
Lyme disease.
Progressive multifocal leukoencephalopathy.
Sarcoidosis.
Whipple's disease.
Listeria rhombencephalitis.
Vasculitis due to systemic lupus erythematosus (SLE).
Acute disseminated encephalomyelitis.

Investigations

• One review of 62 patients found positive serum anti-GQ1b immunoglobulin G (IgG) antibody in 66%, and brain abnormality on MRI scan in 30% of patients.^{[4, 8]}
• The presence of anti-GQ1b antibodies and an abnormal brain MRI scan can help to support its diagnosis but absence of anti-GQ1b antibodies and a normal MRI scan result do not exclude the diagnosis, which remains based on clinical criteria and exclusion of other aetiologies.^[9]
• Electrodiagnostic study results suggested peripheral motor axonal degeneration.

Associated diseases

• A large number of patients have associated Guillain-Barré syndrome, suggesting that the two disorders are closely related.^[8]
• Miller Fisher's syndrome (ophthalmoplegia, ataxia and absent reflexes).^[10]

Management

Success has been achieved with treatment with steroids plus double filtration plasmapheresis.^[11]It has also been achieved with immunoglobulin therapy.^[12] However, there are no randomised controlled trials of immunomodulatory therapy.^[13]

Prognosis

Although the initial presentation is severe, there is usually a good outcome with complete resolution.^[14] Cases of recurrent BBE have been reported.^[9]