Nonaneurysmal Subarachnoid Hemorrhage: A Review of Clinical Course and Outcome in Two Hemorrhage Patterns

Linda L. Herrmann; Joseph M. Zabramski


J Neurosci Nurs. 2007;39(6):135-142. 

In This Article

Perimesencephalic Subarachnoid Hemorrhage Pattern

Perimesencephalic NASAH is characterized by a distinctive pattern of blood seen on an initial CT scan performed within hours of symptom onset. The subarachnoid blood is confined to the midbrain cisterns, with no evidence of intraventricular or intracerebral hemorrhage (Fig 1).

Perimesencephalic subarachnoid hemorrhage accounts for approximately 10% of patients with SAH and for two-thirds of patients with angiographically negative SAH. A review of the literature revealed that patients with perimesencephalic SAH are typically younger and male. Loss of consciousness at hemorrhage onset is rare in these patients, and hydrocephalus is uncommon (Brilstra et al., 1997; Rinkel et al., 1990; Rinkel, Wijdicks, Vermeulen, et al., 1991). Perimesencephalic SAH is associated with a favorable prognosis and a very low risk of rebleeding, hydrocephalus, or delayed cerebral ischemia (Alexander et al., 1986; Biller et al., 1987; Brilstra et al.; Brismar & Sundbarg, 1985; Eskesen, Sorensen, Rosenorn, & Schmidt, 1984; Rinkel et al., 1990; Rinkel, Wijdicks, Hasan, et al., 1991; Schievink, Wijdicks, Piepgras, Nichols, & Ebersold, 1994; Schwartz & Solomon, 1996). Because of the gradual onset of headache and the low incidence of hydrocephalus associated with perimesencephalic SAH, some authors have speculated that its cause may be venous, not arterial (van Gijn et al., 1985).