The advent of magnetic resonance (MR) imaging has permitted the recognition of many angiographically occult vascular malformations before the development of complications and subsequent surgical removal. This study reviews all patients at one institution who had radiographically identifiable vascular malformations believed to represent cavernous angiomas in order to obtain information on the natural history of this particular lesion. All 8131 craniospinal MR images performed at our medical center from January 1, 1986, to November 30, 1989, were reviewed, and 32 patients were identified with 76 lesions meeting the MR imaging criteria for cavernous angioma. Medical histories, physical examination records, and other data from these patients were then reviewed to determine the frequency of complications. Their mean age at latest follow-up examination (or at surgical removal of the lesion) was 37.6 years (range 16 to 72 years). Sixteen patients (50%) had a history of seizures, seven (22%) had focal neurological deficits, and three (9%) had clinically significant hemorrhage attributable to the cavernous angioma; six patients (19%) were asymptomatic. The estimated risk of hemorrhage for this population is 0.25%/person-year of exposure; the estimated risk of seizure development is 1.51%/person-year. Eight patients underwent surgical procedures, resulting in improved seizure control and/or lessened neurological deficit. Although these lesions are often excised with relative ease and minimal morbidity, the potential risks and benefits of surgery must be weighed carefully before removal of these relatively benign malformations.

Clinical findings and magnetic resonance (MR) images in 68 patients with Chiari I malformations were retrospectively analyzed to identify those radiologic features that correlated best with clinical symptoms. A statistically significant (P = .03) female predominance of the malformation was observed, with a female: male ratio of approximately 3:2. Associated skeletal anomalies were seen in 24% of patients. Syringomyelia was detected in 40% of patients, most commonly between the C-4 and C-6 levels. Of the 25 patients who presented with spinal symptoms, 23 (92%) proved to have a syrinx at MR imaging. When the syrinx extended into the medulla (n = 3), however, brain stem symptoms predominated. Patients with objective brain stem or cerebellar signs had the largest mean tonsillar herniations. Patients with tonsillar herniations greater than 12 mm were invariably symptomatic, but approximately 30% of patients with tonsils herniating 5-10 mm below the foramen magnum were asymptomatic at MR imaging. "Incidental" Chiari I malformations are thus much more common than previously recognized, and careful clinical assessment remains the cornerstone for proper diagnosis and management.

Sulcal width, ventricular size, and white matter signal intensity change with age, sex, and race. Knowledge of these changes is important in appropriate interpretation of MR images of the elderly.

The complex process of skull base development is chronicled, which provides CT standards for judgment of the patterns and timing of sutural or synchondrosal closure.

If the lesions reported in this study indicate cerebrovascular disease, subclinical disease may be more prevalent than clinical disease, and the prevalence of disease may rise with age. Also, infarctlike lesions have a distinctive anatomic profile.