Applied Radiology

Diagnosis

Findings

Axial head CT reveals a right thalamic hemorrhage with intraventricular extension (figure 1). Posterior circulation brain MR angiogram maximum intensity projection, lateral view (figure 2) reveals two small right thalamic arteriovenous malformations (AVM) supplied by dilated posterior cerebral artery perforating branches, which were confirmed by catheter angiography, left vertebral artery injection lateral projection (figure 3). Supportive care was continued, and the vascular malformations were treated with the Gamma Knife using stereotactic localization.

Discussion

Known neurovascular complications of cocaine include cerebral infarction related to vasospasm or hypertension, embolic infarction from arrhythmia, intraparenchymal hemorrhage (IPH), and subarachnoid hemorrhage. Intraparenchymal hemorrhage related to typical chronic hypertension is usually due to vessel wall degeneration resulting in local areas of arterial wall weakness, from rupture of small microaneurysms arising from the small perforating vessels, or from an acute rise in blood pressure.1

The mechanisms of cocaine-induced IPH are less well understood. Hemorrhagic conversion of typical ischemic infarction likely constitutes a considerable number of cases. However, most of these hemorrhages are present in the central, deep gray structures of the brain, locations typical of hypertension-induced hemorrhage. Vasospasm of large arteries may jeopardize the small perforating arteries arising from them, either induced directly by cocaine or related to acute hypertension. Alternatively, vasospasm may affect the small perforating vessels directly. The deep gray structures are then prone to reperfusion injury after relief of ischemia. Hemorrhage could also be a direct result of acute hypertension.2-5

However, many studies have shown a high incidence of underlying vascular lesions among patients presenting with intracranial hemorrhage after cocaine use, specifically arteriovenous malformations and aneurysms. In a review of 14 cases of cocaine-related intracranial hemorrhage, Mangiardi et al2 found an underlying AVM or aneurysm in six of the 11 patients who underwent angiography. Similarly, Jacobs et al3 identified vascular lesions in three of eight patients presenting with intracranial hemorrhage.

In elderly chronically hypertensive patients, bleeding often occurs within deep gray matter including the putamen, thalamus, and external capsule, usually from a single perforating artery arising from the middle cerebral or posterior cerebral arteries.6 When bleeding is identified in one of these typical locations in an elderly patient with a history of hypertension, it is usually assumed that the bleed is hypertensive in origin and additional diagnostic workup is not performed. However, this methodology is not employed universally, and additional imaging is commonplace, depending on the institution and physicians involved. When the clinical presentation or imaging findings are atypical (young age, questionable history of hypertension, atypical location), additional imaging is mandatory.

Although many of the reported cocaine-related intraparenchymal hemorrhages are in a typical location for hypertensive hemorrhage (putamen, pons, thalamus, external capsule), additional imaging with MR or catheter angiography should be strongly considered.

1. Caplan L: Intracerebral hemorrhage revisited. Neurology 38:624-627, 1988.

2. Mangiardi JR, Daras M, Geller ME, et al: Cocaine-related intracranial hemorrhage. Report of nine cases and review. Acta Neurol Scand 77:177-180, 1988.

3. Jacobs IG, Roszler MH, Kelly JK, et al: Cocaine abuse: Neurovascular complications. Radiology 170:223-237, 1989.

4. Levine SR, Brust JCM, Futrell N, et al: Cerebrovascular complications of the use of the "crack" form of alkaloidal cocaine. N Engl J Med 323:699-704, 1990.

5. Brown E, Prager J, Lee H-Y, et al: CNS complications of cocaine abuse: Prevalence, pathophysiology, and neuroradiology. AJR Am J Roentgenol 159:137-47, 1992.

6. Laissy J-P, Normand G, Monroc M, et al: Spontaneous intracerebral hematomas from vascular causes. Predictive value of CT compared with angiography. Neuroradiology 33:291-295, 1991.