“BENIGN OR NOT BENIGN”PERIMESENCEPHALIC SUBARACHNOID HAEMORRHAGECASE PRESENTATION

Andrew F. AlaladeST3 Neurosurgery

History

•37 year old male•Sudden-onset occipital headache while

having sex•Described it as the “worse headache” he

ever had•Later became generalised•Had milder episodes in the two weeks

prior to presentation•Associated neck stiffness/pain

• No photophobia• Transient episode of amnesia after sudden onset

headache• Not a known hypertensive

ExaminationGCS – 15/15. No neurological deficitKerning's/ Brudzinki’s signs – negative

FSHDoes not smoke or drink alcohol.No family history of intracranial bleeds

Investigations

•Bloods – FBC, U&E, CRP, ClottingAll parameters within normal limits

•CT Brain•CT Angiography

???Differential diagnoses

Differential Diagnoses

•Subarachnoid haemorrhage- Aneurysmal SAH- Perimesencephalic SAH

•Orgasmic cephalgia•Call-Fleming Syndrome (Idiopathic RCVS)

CT Brain

Subarachnoid haemorrhage

•Traumatic•Spontaneous

- Aneurysmal 80 – 85%- Arteriovenous malformations (AVMs) 4%

- Perimesencephalic 10%- Others: Tumours, anticoagulant therapy, dissection etc.

ACOM aneurysm MCA aneurysm

PCOM aneurysm

“When persons in good health are suddenly seized with pains in the head, and straightway are laid down speechless and breathe with stretor, they die in seven days”

Described a headache due to “immoderate venery”

Hippocrates 460 – 370BC Aphorisms on Apoplexy

Perimesencephalic SAH

•Introduction•Definition•Anatomy•Epidemiology•Clinical features•Complications

It’s all in the name

History

•Cerebral angiography – discovered by Egas Moniz in 1927

•Term (PNSAH) first coined in 1985 by J. Van Gijn et al

Definition• A benign form of non-aneurysmal,

angiographic and MRI –ve SAH with (i) The epicentre of the haemorrhage is anterior

to the midbrain or pons (with or without extension to the ambient cisterns)

(ii) The haemorrhage might occupy the basal(but not the distal) part of the Sylvian fissure and part (but not all) of the interhemispheric fissure

(iii)A sediment of ventricular blood (but not frank IV blood)

Cisterns

Epidemiology

•Age range 3 – 70 years (mean 50 years)•52 – 59% are male•20 – 68% of cases of angiogram-negative

SAH (beware of timing of CT, adequacy of angiography and the definition of PNSAH)True incidence is more in the range of 50 – 75%

Aetiology

•Papers on primitive venous defects/micro-aneurysms

• Variation in size and extension are common and were classified according by Watanabe et al :

- Type A: Normal continuous. The BVR is continuous with the deep middle cerebral vein and drains mainly into the Vein of Galen.

- - Type B: Normal discontinuous.

There is discontinuous venous drainage, anterior to the uncal vein and posterior to the Vein of Galen.

- Type C: Primitive variant. Drainage mainly into veins other than the Vein of Galen.

Some authors have suggested that anatomical variations in BVR arefrequent more prevalent in patients with perimesencephalic non-aneurysmal haemorrhage.

Distal basilar perforator artery aneurysm: case report. Ghogawala Z, Schumacher JM, Ogilvy CS Neurosurgery 1996; 39:393 – 396

Surgical treatment of a basilar artery aneurysm not accessible to endovascular treatment. Hamel W, Grzyska U, Westphal M, Kehler U. Acta Neurochirurgica (Wien) 2005; 147: 1283 – 1286

Distal aneurysms of basilar perforating and circumferential arteries. Report of three cases. Sanchez-Mejia RO, Lawton MT. Journal of Neurosurgery 2007, 107: 654 -9

Life expectancy after perimesencephalic subarachnoid haemorrhage. Greebe P, Rinkel GJ. Stroke 2007; 38:1222-4

• Posterior cerebral artery dissecting aneurysm: another cause of perimesencephalic pattern of subarachnoid haemorrhage P. P. Lobo, J. Campos, L. Neto, P. Canhao J Neurol Neurosurg Psychiatry doi:10.1136/jnnp.2009.198531

• Aneurysmal and microaneurysmal "angiogram-negative" subarachnoid haemorrhage.Tatter SB, Crowell RM, Ogilvy CS.Neurosurgery. 1995 Jul;37(1):48-55.

• Straight sinus Stenosis as a proposed cause of perimesencephalic non-aneurysmal haemorrhage Amjad Shad, Thomas J. Rourke , Ali Hamidian Jahromi and Alexander L. GreenJournal of Clinical Neuroscience Vol. 15, Issue 7, July 2008; 839-841

Types

•Pre-Truncal PNSAH (anterior to the truncus cerebri)Schievink and Wijdicks 1997

•Quadrigeminal PNSAH (in the quadrigeminal cistern)Quadrigeminal variant of perimesencephalic nonaneurysmal subarachnoid haemorrhage.Schwartz TH, Mayer SA. Neurosurgery. 2000 Mar;46(3):584-8.

Clinical features• Clinical picture very similar to classic SAH• Headache can be sudden-onset but develops in

minutes (rather than seconds)• Less frequently hypertensive (3 – 20%)• No seizures/significant reduction in

consciousness• In 1/3rd of the patients, strenuous activities

immediately precede the onset of symptoms (a proportion similar to that found in aneurysmal haemorrhage) van Gijn et al., 1985a; Linn et al., 1998.

• Angiographic negative

Complications

•Hydrocephalus – up to 15%, rarely requires shunting

•Angiographic vasospasm (rare)•Clinical vasospasm (extremely rare)•Hyponatriemia

Overall prognosis is excellent

Other causes of angiographic negative SAH

Angiographic negative, and then positive

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