Modified brainstem auditory evoked responses in patients with non-brainstem compressive cerebral lesions.

The brainstem auditory evoked response (BAER) is sensitive to pontomesencephalic integrity, transtentorial brain herniation, and at times increased intracranial pressure (ICP). The authors report their experience utilizing a recently described rapid rate, binaural, click and 1,000-Hz tone-burst modification of the BAER (MBAER) in 22 symptomatic non-trauma patients with non-brainstem compressive space-taking cerebral lesions. The majority presented with mild to moderate clinical signs suggestive of increased ICP, and focal neurological deficits. The cerebral lesions, mostly tumors (17), averaged 4-5 cm in diameter, with radiological signs of mass effect such as flattening of the sulci, midline shift, and narrowing of the basal cisterns. A number of significant changes in Wave V and V (n) latency and less so amplitude were found in patients compared with age-matched normal volunteers, as well as those again studied after surgical decompression. Similar MBAER changes had been noted in normal volunteers placed in a dependent head position. Possible mechanisms to explain these findings are discussed. The methodology shows promise and if combined with automated peak recognition could make Neuro ICU monitoring practical.

Sir Victor Horsley's contributions to the study and treatment of gunshot wounds of the head.

Sir Victor Horsley'S many contributions to neurological surgery include experimental and clinical studies of gunshot wounds (GSW) of the head. Horsley's publications from 1894 to 1897 and 1914 to 1915 on GSWs were reviewed. Horsley described GSWs in animal and clay models, illustrating characteristics of the primary missile tract and secondary cavitation. A transcranial GSW model in 67 dogs related intracranial damage to the projectile's velocity and sectional area, producing a marked sudden increase in intracranial pressure that presumably "tunneled" to the medullary respiratory and cardiac centers. If the resultant sudden apnea was treated with artificial respiration and prompt surgical decompression, the animal often survived. In these animal experiments, Horsley clearly described increased intracranial pressure, hypertension, and bradycardia-later recognized as the Cushing response or triad. With the onset of World War I, Horsley again reviewed the ballistics of military weaponry, emphasizing projectile spin and velocity as the main wounding mechanisms. He was outspoken against the "wicked tradition" of neglecting cranial GSWs and personally treated cases with aggressive respiratory support and prompt decompression of devitalized tissue. Horsley's contributions to the experimental and clinical aspects of GSWs to the head are consistent with his other important contributions to neurosurgery and have largely stood the test of time.