Question 6

Compare and contrast the clinical manifestations, aetiology, treatment and complications of posterior reversible encephalopathy syndrome (PRES) with herpes simplex virus (HSV) encephalitis

[Click here to toggle visibility of the answers]

College answer

	PRES	HSV encephalitis
Clinical manifestations (4 marks)	The symptoms of PRES evolve rapidly over hours to days Hypertension is frequent but not invariable. The hypertensive crisis may precede the neurologic syndrome by 24 hours or longer. The clinical syndrome of PRES is characterized by headaches altered consciousness ranges from mild somnolence to coma visual disturbances seizures – Seizures are often the presenting manifestation Rarely patients can have symptoms referable to the upper cervical spinal cord (limb weakness, bladder dysfunction), along with one or more of the symptoms above.	Focal neurologic findings are usually acute - <1 week in duration - and include altered mentation and level of consciousness focal cranial nerve deficits hemiparesis dysphasia, aphasia ataxia focal seizures The majority of patients will have one of the above symptoms plus fever

Aetiology (1 mark)	Hypertension Immunosuppressive therapy eg. cyclosporine Renal disease Autoimmune disorders sepsis	HSV
Management (3 marks)	reduction in BP, especially diastolic BP to 100/110 Discontinuation of cytotoxic Seizure therapy Organ failure therapy - in the peripartum setting treat as for eclampsia	IV acyclovir
Complications (2 marks)	ischemia Intracranial haemorrhage death Neurological deficit ranging from severe to mild	-Behavioural abnormalities
		-death
		- cognitive impairment
		-seizures

Discussion

Though the college must be commended for their lucid tabulated answer, the inclusion of "death" in the complications deserves a raised eyebrow (because surely that can't have attracted a grade if the trainees wrote it). Also, just putting "HSV" under the "aetiology" heading would have probably attracted comments like "insufficient knowledge and detail"

Anyway, the specific information regarding HSV encephalitis is derived from by Bradshaw & Ventakesan (2016) for HSV, and Walter Bartynski (Part 1 or Part 2, 2008) for PRES.

PRES vs. HSV encephalitis
HSV encephalitis	PRES
Pathophysiology / aetiology
Viral illness Transmitted along an axon from the ganglion of the trigeminal nerve, where it lays dormant Pathophysiology is inflammatory and (Bradshaw et al, 2016) Characterised by the development of inflammatory cerebral oedema Exhibits tropism for the orbitofrontal and mesiotemporal lobe	Hypertensive disorder Hypertension, followed by failed autoregulation, followed by hyperperfusion As the result of hypertension, permeability of cerebral vessels increases Vasogenic cerebral oedema results
Clinical manifestations
Historical features and symptoms (Sili et al, 2014) Subacute course (>24 hrs) Headache Altered mental status initially Abnormal behaviour Progressively worsening level of consciousness Features on examination Focal signs are possible Fever Seizures CSF biochemistry CSF pleocytosis, mainly lymphocytic Elevated CSF protein HSV PCR positive Radiology/neurophysiology Contrast-enhancing lesions on MRI Evidence of lost grey-white differentiation on CT EEG findings (non-pathognomic)	Historical features and symptoms Headache Visual disturbance Altered mental status Features on examination Blindness Hypertension Seizures CSF biochemistry (Ellis, 2019) CSF pleocytosis Mildly elevated protein Radiology/neurophysiology MRI evidence of oedema Oedema is symmetric (bilateral) Posterior occipital or parietal distribution (but this is not essential): in fact three major anatomical patterns of distribution exist: holohemispheric superior frontal sulcal primary parietal-occipital Nonspecific EEG findings
Treatment
IV aciclovir 10 mg/kg q8h for 14–21 days Foscarnet is a second option	Aggressive control of blood pressure Give antiepileptics if seizures were a presenting problem. Stop the causative drug or arrest the causative process (eg. eclampsia)
Complications
Decreased level of consciousness Seizures, status epilepticus Development of NMDA receptor antibodies	Hypertensive complications (Fischer et al, 2017) Intracranial haemorrhage (eg subarachnoid or intraparenchymal) Status epilepticus Persistent neurological sequelae are rare Persisting epilepsy may occur

References

Staykov, Dimitre, and Stefan Schwab. "Posterior reversible encephalopathy syndrome." Journal of Intensive Care Medicine 27.1 (2012): 11-24.

Bartynski, W. S. "Posterior reversible encephalopathy syndrome, part 1: fundamental imaging and clinical features." American Journal of Neuroradiology 29.6 (2008): 1036-1042.

Bartynski, W. S. "Posterior reversible encephalopathy syndrome, part 2: controversies surrounding pathophysiology of vasogenic edema." American Journal of Neuroradiology 29.6 (2008): 1043-1049.

Bradshaw, Michael J., and Arun Venkatesan. "Herpes simplex virus-1 encephalitis in adults: pathophysiology, diagnosis, and management." Neurotherapeutics 13.3 (2016): 493-508.

Sili, Uluhan, et al. "Herpes simplex virus encephalitis: clinical manifestations, diagnosis and outcome in 106 adult patients." Journal of Clinical Virology 60.2 (2014): 112-118.

Ellis, Colin A., et al. "Cerebrospinal fluid in posterior reversible encephalopathy syndrome: implications of elevated protein and pleocytosis." The Neurohospitalist 9.2 (2019): 58-64.

[Submit a comment or correction]