Clinical Reasoning: Cerebral cavernous malformations

Abstract

A 40-year-old man presented for management of seizures. His first seizure was 5 years earlier. Evaluation at that time revealed a hemorrhagic lesion near the occipital horn of the left lateral ventricle. Incomplete surgical excision was performed with indeterminate pathology suggestive of an astrocytoma. MRI demonstrated 7 separate lesions consistent with cavernous malformations. One measured 1.5 cm in diameter with T2 heterogeneous signal surrounded by a rim of low signal in the medial left temporal lobe. His current seizures have a complex partial semiology and occur 2–4 times per month despite treatment with 2 antiepileptic drugs (AEDs). ### Questions for consideration: 1. Discuss the relationship of cavernous malformations to epilepsy. 2. Discuss the pathologic characteristics, differential diagnosis, and diagnostic evaluation of cavernous malformations. Epileptic seizures are the most common clinical presentation of supratentorial cerebral cavernous malformations (CCMs).1 Since functional neural tissue is not present within CCMs, these lesions are not intrinsically epileptogenic. Rather, they cause seizures through effects on adjacent brain tissue. CCMs have a propensity for recurrent microhemorrhage into adjacent brain resulting in surrounding hemosiderin staining and gliosis.1 These effects, and perhaps local venous hypertension, ischemia, and inflammation, predispose to epileptogenicity. Grossly, CCMs appear raspberry-like, being discretely lobulated, well-circumscribed, and red to purple. Microscopically, CCMs consist of enlarged sinusoidal channels, or caverns, with a simple endothelial lining devoid of elastin and smooth muscle. There is a fibrous adventitia of variable thickness. The caverns may be filled with blood or thrombus. There is no intervening brain parenchyma except possibly at the periphery of the CCM. Hemosiderin is often deposited in the parenchyma sounding the CCM.1 CCMs are low flow lesions that are typically not seen on angiography. MRI is the most sensitive and specific imaging modality for detecting CCMs. CCMs have a characteristic appearance on MRI: they are well-defined, ovoid lesions with a …