Problems encountered during pre-operative embolization in 21 patients with spinal affections could be differentiated as a function of the 3 main regions affected: cervical, dorsolumbar, and lumbosacral. The distinction between the totally different problems raised was based on histologic and angiographic studies of the vascularization of the spinal cord and vertebral column. Whenever possible, and particularly when it can be complete, embolization markedly facilitates the surgical procedure.

Adult↗

PubMedDate not supplied

Gadolinium-enhanced MR of chronic dural sinus thrombosis.

Gadopentetate dimeglumine-enhanced MR imaging was performed in four patients with chronic dual sinus thrombosis. After injection, intense enhancement of the chronic thrombus was observed in all cases. On three-dimensional time-of-flight MR angiography, performed in one case, the occluded part of the superior sagittal sinus was not distinguishable from a normal sinus because of thrombus enhancement mimicking blood flow. Enhancement of the clot is best explained by organization of the thrombus, which is converted into vascularized connective tissue. It could lead to false-negative results in patients with chronic dural sinus thrombosis studied with contrast-enhanced MR or contrast-enhanced time-of-flight MR angiography techniques.

Adult↗

PubMedDate not supplied

Intracranial extension of an idiopathic orbital inflammatory pseudotumor.

Idiopathic orbital inflammatory pseudotumor (IOIP) with endocranial extension is very unusual. The authors used CT and MR to diagnose IOIP and demonstrate the presence of intracranial extension of orbital and lacrimal gland lesions. While providing additional evidence of IOIP having intracranial extension, this case report emphasizes the need to include IOIP as a possible differential diagnosis when radiologic explorations reveal lesions extending from the orbit to intracranial structures.

Adult↗

PubMedDate not supplied

MR determination of hippocampal volume: comparison of three methods.

PURPOSE: To determine whether measurements of the volume of the hippocampal formation obtained from a three-dimensional acquisition not perpendicular to the hippocampus are statistically different from those obtained from a perpendicular acquisition. METHODS: Both hippocampi were studied in 10 healthy volunteers with two three-dimensional acquisitions, allowing three different volume-calculation protocols: (a) on sections from a coronal 3-D acquisition not perpendicular to the axis of the hippocampal formation (NOPERP protocol), (b) on sections obtained with the same acquisition but reformatted perpendicular to the axis of the hippocampal formation (REFOR protocol), and (c) on sections from a coronal 3-D acquisition perpendicular to the axis of the hippocampal formation (PERP protocol) obtained with the patient's head tilted backward. To obtain measurements of the volume of the hippocampal formations, an accurate 3-D processing technique was used to segment the hippocampus. In all subjects, two hippocampal formation right-left asymmetry indexes were calculated by using each of the three protocols. RESULTS: For the right hippocampus, the mean volume was 3.42 cm3 (NOPERP protocol), 4.18 cm3 (REFOR protocol), and 3.91 cm3 (PERP protocol). For the left hippocampus, the mean volume was 3.29 cm3 (NOPERP protocol), 4.02 cm3 (REFOR protocol), and 3.74 cm3 (PERP protocol). For both hippocampi, the differences of the mean volumes were significant between each protocol. However, for both hippocampi, a high correlation was observed between volumes obtained with the different protocols. For the two asymmetry indexes, there were no significant differences for the means obtained with the three protocols. CONCLUSION: With the use of 3-D acquisitions in the study of hippocampal formation biometry, different procedures lead to significant variations in the absolute values of the volume of the hippocampal formation. However, there is a strong correlation between the results obtained by each method.

Adult↗

PubMedDate not supplied

Chronic thalamic stimulation with three-dimensional MR stereotactic guidance.

PURPOSE: To report a method of electrode implantation in the ventralis intermedius nucleus of the thalamus for the treatment of tremor using a 3-D stereotactic MR imaging technique. METHODS: Five patients (three men and two women; mean age, 59 years) with medically refractory tremor had intrathalamic implantation of a stimulating electrode. Stereotactic MR imaging was performed on a 1.5-T unit equipped with an MR-compatible Leksell G stereotactic frame fixed to the patient's head. Calculation of the coordinates of the theoretical target was based on the coordinates of the anterior commissure, the posterior commissure, and the midline sagittal plane as determined via stereotactic MR imaging. During the surgical procedure, the best position for the stimulating electrode was determined by electrophysiological and clinical studies. Postoperative MR control studies were done in all cases to verify the position of the electrode. RESULTS: Stereotactic MR imaging allowed precise implantation of the stimulating electrode in all patients. Electrode stimulation produced a 90% reduction of the tremor in two patients, an 80% and 70% reduction in one patient each, and a persistent microthalamotomy-like effect in the fifth patient. Examination of the MR control studies showed that mean error in the positioning of the electrodes was 0.77 +/- 0.6 mm (mean +/- SD) in the x direction and 0.80 +/- 1.02 mm in the y direction. CONCLUSION: Although our series is relatively small, the precision achieved with stereotactic MR imaging proves that it can be used with confidence for precise functional neurosurgical procedures.

Brain Mapping↗