Viral encephalitis: investigations
Written and reviewed by Dr Ibrahim Imam, Consultant Neurologist. Last reviewed .
Viral encephalitis: investigations. T2 hyperintensities, The insular knife cut sign, Restricted diffusion. Fully referenced neurology checklist.
Magnetic resonance imaging (MRI) brain: features of HSV
- T2 hyperintensities
- The insular knife cut sign
- Restricted diffusion
- Haemorrhages: these appear after 48 hours
- Gyral swelling
- Loss of grey-white matter interface
- Cerebral oedema
- Minimal or no contrast enhancement
- Atrophy and encephalomalacia: subsequently
Cerebrospinal fluid (CSF) analysis
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Other investigations
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References
- Jayaraman K, Rangasami R, Chandrasekharan A. Magnetic resonance imaging findings in viral encephalitis: a pictorial essay. J Neurosci Rural Pract 2018; 9:556-560.
- Marini S, Usai ML, Falso S, et al. Diagnostic value of the "insular knife-cut" sign in patients with suspected herpes simplex virus encephalitis. Eur J Neurol 2025; 32:e70152.
- Solomon T, Michael BD, Smith PE, et al. Management of suspected viral encephalitis in adults-Association of British Neurologists and British Infection Association national guidelines. J Infect 2012; 64:347-373.
- Tunkel AR, Glaser CA, Bloch KC, et al. The management of encephalitis: clinical practice guidelines by the infectious diseases society of America. Clin Infect Dis 2008; 47:303-327.
