Acute Haemorrhagic Leukoencephalitis (AHLE) - Our Experience and a Short Review

Background: Acute haemorrhagic leukoencephalitis (AHLE), a rare variant of acute disseminated encephalomyelitis (ADEM), often presents differently from classical ADEM, thereby posing a diagnostic challenge to the clinician.

Aim: To report AHLE, its clinic-radiological manifestations, process of diagnosis and prognosis.

Method And Results: Eight patients presented with altered sensorium, acute focal deficits with or without seizures. Initial workup showed evidence of haemorrhagic lobar or thalamic lesions in seven patients. All patients underwent extensive evaluation for collagen vascular disease and vasculitis profile, autoimmune encephalitis panel and aquaporin-4 antibody, which were found to be normal. Cerebrospinal fluid (CSF) biochemistry and microscopy was non-contributory and CSF viral PCRs, toxoplasma antibodies, cryptococcal antigen were also negative. All patients had progressively worsening sensorium and neurological deficits. Repeat MRIs showed increase in oedema in the lesions and appearance/expansion of haemorrhage in the thalamic/hemispherical lesions. All patients received intravenous methylprednisolone (IVMP) without any benefit. Four patients underwent plasmapheresis (PLEX), one received intravenous immunoglobulin (IVIG) and one received both second line immunotherapies, without significant improvement. Brain biopsy (performed in three patients) showed inflammatory demyelination and areas of haemorrhage, thus confirming the diagnosis. Six patients succumbed in 7-30 days of the illness, despite aggressive treatment and only two survived, albeit with a significant disability.

Conclusion: AHLE is a rare, yet very severe variant of ADEM. MRI shows lesions with haemorrhages, oedema and mass effect and histology findings reveal inflammatory infiltrates, haemorrhagic foci and fibrinoid necrosis of vessel walls. Prognosis is worse as compared to the classic ADEM, with a high mortality rate. To the best of our knowledge, this is one of the largest series of AHLE to have been reported anywhere in the world.

Keymessage: Acute encephalopathy, multifocal deficits accompanied by haemorrhagic CNS demyelinating lesions with oedema and mass effect are the key features of AHLE. It is a rare, yet very severe form of ADEM with very high morbidity and mortality.