211 Subtentorial Diverticulum of the Third Ventricle Associated with a Mural Cavernous Angioma in a Child Zain Alabedeen B. Jamjoom, M.D., Saif Abdul-Aziz, M.D., Abdul-Hakim Jamjoom, F.R.CS., Ed. (NS), Naim-Ur-Rahman, F.R.CS. Ed. (NS), and Mohammad Abdul-Jabbar, M.R.CP. (C) Divisions of Neurosurgery and Neurology, and Department of Pathology, College'of Medicine, King Saud University, Riyadh, Saudi Arabia Jamjoom ZAB, Abdul-Aziz S, Jamjoom A-H, Rahman N-U, Abdul-Jabbar M. Subtentorial diverticulum of the third ventricle associated with a mural cavernous angioma in a child. Surg Neural 1994;42:211-17. The authors describe a case of a large subtentorial su- pracollicular diverticulum of the third ventricle asso- ciated with a cavernous angioma in its wall in a 6-year- old girl who presented with developmental delay and obstructive hydrocephalus. This is the first case in which such association has been diagnosed and success- fully treated. The literature is reviewed, and the possible relationship between these two rare lesions is discussed. KEY WORDS: Cavernous angioma; Computer tomography; Di- verticulum; Magnetic resonance imaging; third ventricle A ventricular diverticulum is a cystic subpial collection of cerebrospinal fluid (CSF) resulting from rupture of the ependymal lining of the ventricular system in cases of advanced hydrocephalus [28}. The condition was first described by Penfield [27} in 1929, and according to Wakai et al [36} 51 cases have been reported in the pertinent literature until 1983. Since then only a few new cases have been added [9,26}. With a few excep- tions [7,9,25}, the hydrocephalus was secondary to an obstructive lesion, mostly "benign" aqueductal stenosis [2,3,7,8,14,18,22,28,33,37,38}. Less frequently, brain stem tumors [7,14,28,31,32} and third ventricle tumors [5,27} were the cause of obstruction. The association of a ventricular diverticulum with a cavernous angioma has, to the best of our knowledge, never been reported before. In this report, we describe the first case of a large diverticulum of the third ventricle occupying the qua- drigeminal cistern and associated with a cavernous an- Address reprint requests to: Dc. Zain Alabedeen B. Jamjoom, Divi- sion of Neurosurgery, College of Medicine, King Saud University, P. O. Box 2925, Riyadh 11461, Saudi Arabia. Received December 3, 1993; accepted January 12, 1994. © 1994 by EIsevier Science Inc gioma in its wall. This type of vascular malformation has been rarely encountered in the quadrigeminal re- gion, and according to Hahn et al [lO}, only seven of some 598 (= 1.2%) intracranial cavernous angiomas collected from the literature were located there. The relationship between these two rare pathologic entities is discussed. Case Report A 6-year-old girl was referred to the Neurosurgical Division of the King Khalid University Hospital be- cause of progressive difficulty of walking, delayed speech, and abnormal rolling of the eyes since the age of three. Compured tomography (CT) scan of the head revealed a nonenhancing, high attenuation area (measur- ing 18 x 12 mm) dorsal to the midbrain associated with obstructive hydrocephalus (Figure 1 A). There was also a midline cyst in the posterior fossa (measuring 28 x 31 mm) that communicated with the third ventricle (Fig- ure 1 B). On magnetic resonance imaging (MRI), the cyst gave signal intensities identical with those of the cerebrospinal fluid. The lesion dorsal to the brain stem consisted on both T 1- and T 2-weighted images of an irregular hyperintense core surrounded by a hypointense peripheral area. The exact anatomic relationship among the cyst, lesion, and surrounding neural structure was best demonstrated on the T I-weighted midsagittal MRIs (Figure 2). It showed an infratentorial and supra- quadrigeminal cyst communicating with the third ven- tricle through a small opening at the level of the pineal recess. At the inferior pole of the cyst wall dorsal ro the pons, a lobulated hyperintense lesion was present. The aqueduct of Sylvius was severely compressed and the floor of the dilated third ventricle herniated caudally into the sella turcica and the prepontine spaces. Examination The girl was fully alert but showed a marked degree of mental and motor retardation. She could speak only a 0090-3019/94/$7.00