The non-traumatic perimesencephalic subarachnoid haemorrhage (PMH) - A subgroup of subarachnoidal haemorrhages with good prognosis?

Perimesencephalic subarachnoidal haemorrhage (PMH) is characterized by a typical blood distribution pattern in the basal cysterns in the CAT, missing evidence of an aneurysm in the panangiogram, a mild clinical course and a very positive prognosis. Between 1990 and 1995, 108 inpatients with non-traumatic subarachnoidal haemorrhage were treated in our clinic. Within this group 14 patients (13%) were identified retrospectively with a perimesencephalic haemorrhage distribution pattern in the CAT and a negative panangiogram. These patients experienced a mild clinical course with excellent outcome without rebleeding during the observation period of 2 to 50 months. All patients were fully able to work, and only two patients complained of frequent headaches. The mild clinical course, the negative panangiogram as well;Is the extremely positive outcome confirm the hypothesis of of a benign subgroup of non-traumatic subarachnoidal haemorrhages.