Perimesencephalic and nonperimesencephalic subarachnoid haemorrhages with negative angiograms

van Gijn and co-workers identified "Perimesencephalic haemorrhage" (PM) as distinct, benign, non-aneurysmal subarachnoid haemorrhage. However, there is only one retrospective series of this entity outside the Netherlands.

to confirm (or not) the benign nature of perimesencephalic subarachnoid haemorrhage by evaluating its clinical course and long-term follow-up in a consecutive series of patients admitted to a University Hospital.

Patients with subarachnoid haemorrhage and negative cerebral angiography admitted between January 1985 and April 1992 were classified according to the distribution of blood on a CT scan performed within 72 hours after onset, in perimesencephalic and non-perimesencephalic haemorrhages. Demographic and clinical data (collected consecutively), complications and long-term follow-up (obtained by chart review and follow-up by mail) were compared in the two groups.

Seventy one cases, 36 perimesencephalic and 35 nonperimesencephalic were included. Sex and age distribution were similar in the two groups. A normal examination on admission was the rule in the perimesencephalic group. Only one patient with perimesencephalic haemorrhage had a complication--transient neurological signs during angiography--and there were no deaths or morbidity during follow-up. In the non-perimesencephalic group three patients rebleed, four developed hydrocephalus and two had delayed cerebral ischaemia. Mean duration of follow-up was 27.6 months for the perimesencephalic and 30.8 months for the non-perimesencephalic group. After discharge there was a fatal rebleed in the latter group. Fifteen percent of the subjects (11% of the perimesencephalic group and 20% of the non-perimesencephalic group) retired from work during the follow-up period. Headaches and depression were found in similar percentages (22-25%) in both groups.

This study confirms that perimesencephalic haemorrhage is a distinct entity within the larger group of subarachnoid haemorrhage with negative angiograms, with a good short term and long-term prognosis, and no need for repeated angiographic investigation.