Acute haemorrhagic encephalomyelitis (AHEM), also known as acute haemorrhagic leukoencephalitis (AHLE), Hurst disease or Weston-Hurst syndrome, is a very rare form of demyelinating disease. It occurs sporadically and may be considered as the most severe form of acute disseminated encephalomyelitis (ADEM) and is characterised by an acute rapidly progressive fulminant inflammation of the white matter. The cause is unclear but may be post-infectious (either viral or bacterial).
AHEM may more commonly occur in young adults, contrary to ADEM, which is more commonly diagnosed in children 5. It has been reported in older adults 6. There is no gender predilection.
Patients present with fever, neck stiffness, fatigue, headache, nausea and vomiting, seizures and coma.
A history of upper respiratory infection prior to presenting neurologic symptoms (interval 2 to 12 days) may be present in ~50% of cases 4.
AHEM is related to autoimmune cross reaction to the myelin antigens. Many authors consider it a variant of ADEM, forming a spectrum of disease 4-5.
AHEM may be considered the fulminant form of ADEM. It is defined by the presence of necrotising venulitis with perivascular haemorrhages, diffuse CNS ischemic lesions and myelin destruction 4.
- marked cerebral oedema and congestion, often with herniation
- punctate hemorrhages within the cerebral white matter, not infrequently necrotic
- not uncommonly presence of necrosis in basal ganglia
- typically no involvement of spinal cord
Imaging appearances are dominated by fibrinoid venous necrosis, leading to acute hemorrhage with fibrin exudates and neutrophilic debris:
- classically hemorrhages around the necrotic venules resembling “ring and ball”
- white matter ischemic changes adjacent to necrotic postcapillary venules
- haemorrhage more prominent than demyelination
- no specific immunohistochemical pattern 4
This is the gold-standard and may depict aforementioned morphologic changes such as:
- large tumefactive lesions involving the white matter and sparing the cortex
- associated punctate haemorrhages and extensive mass effect and surrounding edema.
- possible involvement of ganglia and thalami
Detection of the punctate haemorrhages by GRE (T2*WI) images or the more sensitive susceptibility weighted images (SWI) is an important finding and may allow for differentiation from ADEM.
Treatment and prognosis
Acute haemorrhagic leukoenceplalitis is associated with a very poor prognosis. It is well known to demonstrate initial good response to steroids with subsequent new onset of symptoms and devastating outcome. Aggressive therapeutic management is a prerequisite to avoid usual disease course with fatal outcome.
General imaging differential considerations include:
- acute disseminated encephalomyelitis (ADEM): probably the milder form of the same disease
- severe demyelination / multiple sclerosis
- herpes simplex encephalitis
- cerebral vasculitis
- primary demyelinating disorders
- clinically isolated syndrome (CIS)
- radiologically isolated syndrome (RIS)
- multiple sclerosis (MS)
- neuromyelitis optica (NMO) (Devic disease)
- acute disseminated encephalomyelitis (ADEM) and acute haemorrhagic encephalomyelitis (AHEM)
- tumefactive demyelinating lesions
- transverse myelitis
- chronic inflammatory demyelinating polyneuropathy (CIDP)
- Guillain-Barre Syndrome (GBS)
- primary demyelinating disorders
- 1. Geerts Y, Dehaene I, Lammens M. Acute hemorrhagic leukoencephalitis. Acta Neurol Belg. 1992;91 (4): 201-11. Pubmed citation
- 2. Hurst AE. Acute hemorrhagic leukoencephalitis: a previously undefined entity. Med J Aust 1941;1:1–6
- 3. Lee HY, Chang KH, Kim JH et-al. Serial MR imaging findings of acute hemorrhagic leukoencephalitis: a case report. AJNR Am J Neuroradiol. 2005;26 (8): 1996-9. Pubmed citation
- 4. Yachnis AT, Rivera-Zengotita ML. Neuropathology,A Volume in the High Yield Pathology Series (Expert Consult - Online and Print),1. Saunders. (2013) ISBN:1416062203. Read it at Google Books - Find it at Amazon, pp. 287-8
- 5. Borlot F, da Paz JA, Casella EB et-al. Acute hemorrhagic encephalomyelitis in childhood: Case report and literature review. J Pediatr Neurosci. 2011;6 (1): 48-51. Free text at pubmed - Pubmed citation
- 6. Pinto PS, Taipa R, Moreira B et-al. Acute hemorrhagic leukoencephalitis with severe brainstem and spinal cord involvement: MRI features with neuropathological confirmation. J Magn Reson Imaging. 2011;33 (4): 957-61. doi:10.1002/jmri.22505 - Pubmed citation