The classification of spinal meningeal cysts (MC's) in the literature is indistinct, confusing, and in certain categories histologically misleading. Based on a series of 22 cases, the authors propose a classification comprising three categories: spinal extradural MC's without spinal nerve root fibers (Type I); spinal extradural MC's with spinal nerve root fibers (Type II); and spinal intradural MC's (Type III). Although water-soluble myelography may disclose a filling defect for all three categories, computerized tomographic myelography (CTM) is essential to reveal communication between the cyst and the subarachnoid space. Communication demonstrated by CTM allows accurate diagnosis of a spinal MC and rules out other mass lesions. Magnetic resonance imaging appears useful as an initial study to identify an intraspinal cystic mass. Final characterization is based on operative inspection and histological examination for all three categories.

These pilot data suggest that an individual's experimental pain threshold (a measure of tenderness) is associated with baseline functional status and pain in cases of chronic low back pain and may represent an important domain warranting further investigation.

Stereotactic multicontact electrodes used to probe the cerebral cortex of a middle aged woman with progressive dementia were previously implicated in the accidental transmission of Creutzfeldt-Jakob disease (CJD) to two younger patients. The diagnoses of CJD have been confirmed for all three cases. More than two years after their last use in humans, after three cleanings and repeated sterilisation in ethanol and formaldehyde vapour, the electrodes were implanted in the cortex of a chimpanzee. Eighteen months later the animal became ill with CJD. This finding serves to re-emphasise the potential danger posed by reuse of instruments contaminated with the agents of spongiform encephalopathies, even after scrupulous attempts to clean them. (7 NeurolNeurosurg Psychiatry 1994;57:757-758) More than 15 years ago, Creutzfeldt-Jakob disease (CJD) was accidentally transmitted to two young people by stereotactic electroencephalographic (SEEG) exploration with multicontact probe electrodes that had previously been implanted in the brain of a middle aged patient with familial presenile dementia and myoclonic jerks.' The electrodes apparently remained contaminated with the infectious agent of CJD despite attempts to sterilise them with alcohol and formaldehyde vapour. The purpose of this communication is to document that the diagnoses of all three patients have been confirmed by transmission of disease to animals and to describe the transmission of CJD to a chimpanzee by implantation of the same electrodes used in the two iatrogenic cases after sterilisation and storage in formaldehyde vapour for two years after their last use in humans. We failed to transmit disease to another animal, the brain of which was implanted with gold wire electrodes that had been glued to the scalps of the three patients and then cleaned with the same regimen used for the silver electrodes. Methods and resultsIn September 1974, two multicontact depth electrodes (probe electrodes with multiple silver contacts separated by rings of insulating plastic) were used to explore the cerebral cortex of the source patient with CJD, and SEEG recordings of electrical activity were conducted at various depths in the cortex, subcortical white matter, caudate nucleus, and ventrolateral thalamus to select suitable sites for brain biopsy and thermocoagulation. The electrodes were in place for about two hours after which they were removed, cleaned with benzene, disinfected with 70% ethanol, and placed in a preautoclaved metal box containing a formaldehyde generator (2 g paraformaldehyde) where they were stored for two months. In November 1974 the two silver electrodes were implanted for a period of several hours in the cerebral cortex of a 23 year old woman with drug resistant psychomotor epilepsy, after which they were again cleaned, sterilised, and stored as described. In December 1974 these same silver electrodes were implanted for a period of several hours in the cortex of a 17 year old boy with postencephalitic psychomotor epilepsy. After their last us...

The value of skull radiography in identifying intracranial injury has not yet been satisfactorily defined. A multidisciplinary panel of medical experts was assembled to review the issue of skull radiography for head trauma. The panel identified two main groups of patients--those at high risk of intracranial injury and those at low risk of such injury--and developed a management strategy for imaging in the two groups. The high-risk group consists primarily of patients with severe open or closed-head injuries who have a constellation of findings that are usually clinically obvious. These patients are candidates for emergency CT scanning, neurosurgical consultation, or both. The low-risk group includes patients who are asymptomatic or who have one or more of the following: headache, dizziness, scalp hematoma, laceration, contusion, or abrasion. Radiographic imaging is not recommended for the low-risk group and should be omitted. An intermediate moderate-risk group is less well defined, and skull radiography in this group may sometimes be appropriate. A prospective study of 7035 patients with head trauma at 31 hospital emergency rooms was conducted to validate the management strategy. No intracranial injuries were discovered in any of the low-risk patients. Therefore, no intracranial injury would have been missed by excluding skull radiography for low-risk patients, according to the protocol. We conclude that use of the management strategy is safe and that it would result in a large decrease in the use of skull radiography, with concomitant reductions in unnecessary exposure to radiation and savings of millions of dollars annually.