The recent epidemic of cocaine abuse, especially among young individuals, has caused increasing concern about the potential hazards of prenatal cocaine exposure on the developing fetus and newborn. Although large-scale epidemiologic studies and long-term data are lacking, a review of the literature suggests strongly that the popular belief about the relative safety of cocaine is unfounded and that maternal cocaine abuse during pregnancy may be associated with increased perinatal morbidity and mortality.

Shunt complications are reported to occur at a rate of approximately 26%. One of the less frequent but important complications is that of the pseudocyst. Since Harsh's first mention of a periumbilical cyst associated with a shunt in 1954, 44 cases have been reported in the literature. These are reviewed in addition to 12 cases of our own. From the collected series several features about the etiology and management become apparent. The most common presentation is that of abdominal distension and/or pain rather than shunt malfunction. Diagnosis is then readily made with ultrasonography. Etiologically, it is evident that an inflammatory process is a frequent predisposing factor. In our series 16% had acute infection, 41.6% had a past history of CSF infection (6 months to 6.2 years), and 16% had CNS tumor although tumor cells were not isolated from the peritoneal cysts. Our management of the cyst itself was different from that reported in other series; it was found that the cyst reabsorbed spontaneously without excision or aspiration once the CSF was diverted. The peritoneal cavity could then be used for shunting once the cyst had reabsorbed. This sometimes required conversion to an atrial or pleural shunt before reutilization of the peritoneal cavity. There were no problems with cyst recurrence despite the conversion of 58% of the shunts to ventriculoperitoneal shunts with follow-up ranging from 3 months to 4 years. The mode of management of both the cyst and the hydrocephalus is reviewed.

Eighteen children or adolescents with intracranial arteriovenous malformations (AVM) underwent stereotactic radiosurgery using the first North American gamma knife. This closed-skull, single-treatment therapy, utilizing 201 ionizing beams of gamma-irradiation, was used as an alternative to microsurgical removal in these selected patients (aged 34 months to 18 years, mean 12.3 years) beginning in August 1987. No significant perioperative morbidity occurred, and no patient rebled or died in the follow-up interval ranging between 7 and 19 months. Computed tomography (CT) and magnetic resonance imaging (MRI) were used to monitor the response to treatment and to determine when postoperative angiography was indicated. Of seven AVMs examined with cerebral angiography 1 year after treatment, three were completely obliterated; three others were significantly smaller, and their complete obliteration is anticipated by 2 years after treatment. Follow-up CT or MRI confirmed attenuation or signal changes suggestive of edema surrounding the treatment volume in 3 patients; 1 had transient worsening of a preexisting neurological deficit. Although a more long-term perspective is still required for this new technology now available in the United States, we believe that gamma knife stereotactic radiosurgery is a safe and effective method to obliterate AVM deemed too risky for microsurgical removal.

A lymphoblastic sarcoma mimicked a medulloblastoma in a 15-year old girl with a history of acute lymphoblastic leukemia diagnosed at age of 2 years. There was no evidence of leukemic infiltration in the brain during the 13-year latency period after the original diagnosis. She had received both prophylactic intrathecal methotrexate and central nervous system irradiation. This case emphasizes the need to consider leukemia as the cause of a 'brain tumor' in any patient that has a prior history of leukemia, regardless of the tumor manifestations or the remission duration of the leukemia.

Ectopic immature renal tissue was found in a lumbosacral subcutaneous lipoma with intradural extension in a 6-day-old female with spina bifida. No additional neurologic or renal anomalies were found. Ectopic renal tissue is an extremely rare finding. Histopathologic and MRI results from this case are presented and the possible significance of ectopic renal tissue in relation to the origin of extrarenal Wilms' tumors is discussed.

A relatively unusual cause of progressive paraparesis is a spinal arachnoid cyst. The following is a case report of this lesion in an adolescent. The CT-myelographic and MR features, as well as the management of this case are discussed, followed by a review of the pertinent English literature on this topic.

A family with two sisters and their mother's male cousin had ependymomas. Of note is the fact that chromosome analysis on the tumour of the younger sister showed two cell lines, one a normal female line, the other with monosomy of chromosome 22.

In young achondroplastic children, neurological manifestations have been found to include macrocephaly, hydrocephalus or ventriculomegaly and cervicomedullary compression. Occasionally in the second decade, lumbar radiculopathy or paraparesis resulting from severe thoracolumbar kyphosis develops. In this paper, we report the unique case of an achondroplastic dwarf who developed paraplegia due to thoracolumbar spinal cord compression at the age of 7 months. Compromise of the spinal canal was found to be due not to bony stenosis, but to a second layer of fibrous tissue, histologically identical to the dura. Treatment consisting of decompressive laminectomy and resection of the constricting tissue allowed the child to recover completely. Clinical, radiographic and pathological findings are discussed.

Twelve patients with shunt infection occurring more than 6 months following shunt implantation or revision were identified and their charts reviewed. These cases were accumulated over a 9-year period, and delays from shunt surgery to detection were as long as 11 years. For 5 patients, no antecedent infection or surgery could be identified as a presumptive cause of the shunt infection. Propionibacterium species and Staphylococcus epidermidis species were the most common organisms identified. The risk of late onset of infection at this institution is less than 1% per year.

An 11-year-old girl with repeated pneumococcal meningitis after head injury is reported. High resolution CT scan with metrizamide cisternogram disclosed a fracture in petrous bone with collection of contrast medium in middle ear. Operative repair of the dura defect successfully stopped further intracranial infection. In cases of late posttraumatic infection, aggressive survey of the skull base is indicated.