Furthermore, possible correlations between white matter lesion scores, ventricular width, and age were investigated. Normal-pressure hydrocephalus (NPH) is a potentially treatable syndrome with abnormal cerebrospinal fluid dynamics. Meningeal fibrosis and/or obliteration of the subarachnoid space has been suggested as the pathoanatomic basis. The purpose of the present study was to investigate whether meningeal fibrosis causes increased resistance to cerebrospinal fluid outflow (R(out)) and/or increased B-wave activity and whether pathological changes in the brain parenchyma after brain compliance, causing increased B-wave activity.

The study involved a group of 38 consecutively studied patients with clinical and radiological evidence of idiopathic NPH, for whom a frontal brain biopsy was obtained. For 29 patients, hydrodynamic criteria of NPH were fulfilled and a ventriculoperitoneal shunt was performed. The dosimetry was characterized by two independent methods: thermoluminescent dosimeters and radiochromic film.

The results suggest that leptomeningeal fibrosis is not the only pathoanatomic basis of increased R(out) and/or B-wave activity in patients with NPH and that various degenerative changes in the parenchyma may be responsible for the altered cerebrospinal fluid dynamics characteristic of NPH. The purpose of this study was to determine the efficacy of spinal cord stimulation (SCS) in patients with symptoms of reflex sympathetic dystrophy (RSD), a disabling clinical condition with significant consequences of morbidity and loss of productivity.

We have used epidural SCS for pain control during the past 15 years. An analysis of our records revealed 12 consecutive patients diagnosed as having RSD before undergoing SCS. Eight of the 12 patients had undergone previous ablative sympathectomy. All 12 patients experienced relief of pain after trial stimulation and had their systems permanently implanted.

At an average of 41 months follow-up, all patients were using their stimulators regularly and only two were receiving adjunctive minor pain medication. The level of pain present pre- and postoperatively was determined by administering a modified McGill Pain Questionnaire and a visual analog scale to each patient. Both dosimetric methods showed a steep dose-distance fall-off relationship (proportional to the reciprocal of the cube of the distance from the probe tip).

Eight patients reported excellent pain relief, and four patients described good results. SCS is an effective treatment for the pain of RSD, including recurrent pain after ablative sympathectomy. The low morbidity of this procedure and its efficacy in patients with refractory pain related to RSD suggest that SCS is superior to ablative sympathectomy in the management of RSD.

We report the design and initial characterization of the dosimetry and radiobiology of a novel device for interstitial stereotactic radiosurgery. The device is lightweight, handheld, and battery-powered, and it emits x-ray radiation from the tip of a probe 3 mm in diameter by 10 cm in length. Heat transfer from the probe to dog brain was studied in vivo by placing thermocouple sensors around the probe tip before irradiating.

The radiobiology was characterized by in vivo irradiation of rat liver, dog liver, and dog brain. The animals were killed at varying intervals of time, and histological examinations were performed. Rats and dogs that were killed weeks to months after liver irradiation tended to have sharply demarcated lesions. Liver enzyme levels, measured serially in the dogs, did not give evidence of chronic inflammation.

Histological examination of the brains of dogs that were killed acutely after irradiation did not show evidence of inflammation, edema, or hemorrhage. The tissue temperature elevation 1 cm from the tip never exceeded 0.5 degree C, thereby excluding hyperthermia as a significant contributor to the formation of lesions.