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Show EDITORIAL Why Would a Spinal Tumor Cause Increased Intracranial Pressure? Harold L. Rekate, MD Abnormalities of intracranial pressure dynamics have been reported to occur in the context of a variety of spinal cord tumors. In this issue of the Journal of Neuro- Ophthalmology, Costello et al. describe a woman with visual symptoms caused by papilledema. A magnetic resonance imaging scan of the brain was normal, and lumbar puncture showed an opening pressure of 290 mm water and a protein content of 114 mg/ dl but an otherwise normal cerebrospinal fluid ( CSF) formula. Spine imaging later disclosed a low sacral tumor. The papilledema resolved after the resection of the tumor. Extramedullary and intramedullary spinal cord tumors apparently cause both hydrocephalus ( increased intracranial pressure with ventriculomegaly) and the pseudotumor cerebri syndrome ( increased intracranial pressure without ventriculomegaly). The causes of the CSF absorptive problems in the context of these tumors have been adequately explained in a majority of the cases. Malignant tumors, including glioblastomas in adults and neuroblastomas in children, usually cause hydrocephalus resulting from widespread meningeal spread. Whereas CSF cytology is often noncontributory in these cases, the diagnosis can usually be made either by neuroimaging or by meningeal biopsy if needed. In some cases, however, the only abnormalities involve mild increases in the CSF protein levels, as seen in the patient described here. Why do these patients have increased intracranial pressure? At present, there are no compelling answers to this question. It is very unlikely that the tumor itself has any direct blocking effect on the absorption of the CSF. Although there are several proposed alternative sites for CSF absorption, most of the CSF is absorbed at the interface between the cortical subarachnoid space and the dural venous sinuses. Other causes of compression of the thecal sac, such as fracture or epidural tumor, have not been reported in association with either hydrocephalus or pseudotumor cerebri. In some cases, the CSF protein levels are sufficiently high to lead to sludging at the level of the arachnoid villi, but not all reports of hydrocephalus or the pseudotumor cerebri syndrome in patients with spinal cord tumors are associated with high levels of protein. Most cases show only modest increases. The most likely explanation for elevated intracranial pressure in those cases may relate to the release of a tumor- generated chemical into the CSF that leads to failure of CSF absorption. Removal of the tumor will then lead to the normalization of intracranial pressure. Several potential chemical markers have been suggested. One is fibrinogen, which is converted to fibrin in the CSF. If fibrin creates a blockage at the level of the basal cisterns, it would cause hydrocephalus. If it creates a blockage at the level of the arachnoid villi, it could lead to the pseudotumor cerebri syndrome ( 1). Another interesting candidate is the inflammatory cytokine TGF( 3. Found in a variety of primarily vascular structures such as the choroid plexus, TGF( 3 is present in high concentrations in Departments of Pediatric Neurosciences and Clinical Neurosurgery, Barrow Neurological Institute, Phoenix, Arizona, and Department of Surgery, University of Arizona College of Medicine, Tucson, Arizona. Address correspondence to Harold L. Rekate, MD, 2910 North Third Avenue, Phoenix, AZ 85013, USA; E- mail: harold. rekate@ bnaneuro. net nJNewo- OpMiqlwol,. Vol. 22, No^, l 2002 „ ,„,.,.. . . DOI: 10.1097/, 01. WNrO. pQ00028 § 80.83.393.8F , J97 , Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited JNeuro- Ophthalmol, Vol. 22, No. 3, 2002 Rekate platelets and has been shown to result in the proliferation of leptomeningeal cells and the creation of scarring both at the base of the brain and in the area of the arachnoid villi ( 2). The final explanation for increased intracranial pressure in the presence of spinal cord tumors will have to await further delineation of the chemical composition of the CSF in these patients. REFERENCES 1. Cinalli G, Sainte- Rose C, Lellouch- Tubiana A, et al. Hydrocephalus associated with intramedullary low- grade glioma: illustrative cases and review of the literature. J Neurosurg 1995; 83: 480- 5. 2. Motohashi O, Suzuki M, Yanai N, et al. Thrombin and TGF- beta promote human leptomeningeal cell proliferation in vitro. Neurosci l e a 1995; 190: 105- 8. „ 198 „ . . „ . . © 2002 Lippincott Williams & mikins , Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. |
