Brain tissue pressure gradients created by expanding frontal epidural mass lesion.

A porcine model was used to study the regional intracranial pressure (ICP) differences caused by a frontal mass lesion. Intraparenchymal ICP monitors were placed in the right and left frontal lobes, right and left temporal lobes, midbrain, and cerebellum. A frontal epidural mass lesion was created by placing a balloon catheter through a burr hole into the right frontal epidural space. A computer was used to acquire data from all monitors at 50-msec intervals. The balloon was expanded by 1 cc over a period of 1 second every 5 minutes and maximum pressure immediately before and during expansion was determined for each balloon volume at each site. Prior to expansion of the mass, the morphology of the cerebellum pressure tracing was different from that seen in all supratentorial regions. Also, pressures in the midbrain, at baseline, were slightly but significantly lower than pressures in the frontal and temporal regions. During expansion of the mass, a pressure differential that increased as the size of the mass increased developed between intracranial regions. Furthermore, the regional pressures were found to vary in a consistent fashion expressed by the formula RF=LF>RT=LT>MB>CB, in which RF and LF are the right and left frontal lobes, RT and LT are the right and left temporal lobes, MR in the midbrain, and CB is the cerebellum. The study shows that an expanding epidural mass reproducibly results in a gradient of brain parenchymal pressure. This gradient results in parenchymal pressures that are significantly different in each region of the brain depending on the proximity of that region to the epidural mass. The results of this study have implications for clinical ICP monitoring and therapy.

Quantification of thyrotropin-releasing hormone changes and serotonin content changes following graded spinal cord injury.

Thyrotropin-releasing hormone (TRH) and serotonin (5-HT) are well known as neurotransmitters of descending bulbo-spinal tracts. 5-HT uptake caudal to (5-HT decreased) graded spinal lesions has been measured in rats and dogs and significantly correlated with the degree of cord injury. We studied 5-HT content via high-pressure liquid chromatography and radioimmunoassay measurements of TRH in dog spinal cord, both rostral and caudal, to 6 week T6 spinal transection (T) (n = 7) or T6 hemisections (H) (n = 7). Sham controls (n = 7) were used. Mean 5-HT content values were (pmole/mg): rostral sham 1.25 +/- 0.02, caudal sham 1.35 +/- 0.17, rostral T 2.65 +/- 0.36, caudal T 0.19 +/- 0.06, rostral H 2.1 +/- 0.22, and caudal H 1.0 +/- 0.31. A significant decrease in 5-HT caudal to transection versus control (P < 0.001) was seen. A trend for decreased 5-HT caudal to hemisection versus control (P < 0.1) was also seen. Mean TRH levels (pg/mg protein) were: rostral sham 40.02 +/- 18.47, caudal sham 30.61 +/- 10.03, brainstem sham 18.9 +/- 5.13, rostral T 52.4 +/- 21.34, caudal T 3.52 +/- 1.87, brainstem T 19.25 +/- 4.11, rostral H 43.45 +/- 18.61, caudal H 14.24 +/- 5.7, and brainstem H 21.89 +/- 1.23. Significant decreases for caudal TRH transection versus controls (P < 0.001) and for caudal TRH hemisection versus controls (P < 0.02) were seen. A significant difference between caudal hemisection and caudal transection TRH levels (P < 0.001) was seen.(ABSTRACT TRUNCATED AT 250 WORDS)

Efficacy of dorsal longitudinal myelotomy in treating spinal spasticity: a review of 20 cases.

The authors report their experience using dorsal longitudinal myelotomy in treating spasticity in 20 patients with complete spinal cord injuries. These patients suffered from severe painful flexor/extensor spasms that prevented them from wheelchair ambulation and/or their decubitus ulcers healing. All were receiving large doses of various oral drugs, including baclofen, which had failed to control their spasticity, and all underwent a modification of a posterior T-myelotomy as first described by Bischof. All 20 patients enjoyed immediate complete relief of their painful spasms, although two (10%) eventually experienced return of their spasms and are thus classified as long-term failures. Seventeen patients succeeded in markedly reducing, or being completely weaned from, their antispasmodic medications. In 11 of 14 patients, nonhealing decubitus ulcers subsequently healed with treatment. Bladder function was unchanged from the preoperative status in all patients. Chronic intrathecal baclofen infusion has recently been reported as an effective treatment of the spasticity of paraplegia. The results of this study, along with previous reports advocating dorsal longitudinal myelotomy, suggest that this approach is an efficacious alternative to chronic baclofen infusion in reducing spasticity for complete paraplegics. Considering the cost of the infusion pump, along with the fact that chronic intrathecal baclofen therapy necessitates long-term medical supervision, it appears that myelotomy is superior for this select group of patients who have no hope of regaining voluntary motor function.

Bilateral anterior cerebral artery infarction resulting from explosion-type injury to the head and neck.

A 43-year-old woman suffered a blast-type injury to the head and neck. She subsequently developed bilateral internal carotid artery occlusion and bilateral anterior cerebral artery infarction not demonstrated by magnetic resonance imaging scan 24 hours after the explosion, but confirmed by a second scan 8 days after the explosion. In patients with blast-type injury to the head and neck who develop coma with a nonfocal neurological exam, the possibility of bilateral carotid artery occlusion and bilateral ischemic infarction should be considered.

Magnetic resonance imaging diagnosis of a cerebral aneurysm in an infant. Case report and review of the literature.

A posterior cerebral artery aneurysm presented as a seizure disorder in a 7-week-old infant. A small hemorrhage in the posterior thalamus was seen on CT scan. However, magnetic resonance imaging (MRI study) demonstrated an aneurysm and appropriate therapy was carried out. The incidence, natural history, etiology, and surgical treatment of these lesions are reviewed, and the usefulness of MRI in their diagnosis is emphasized.