Effects of hypotension on rhesus monkeys.

Twenty-one late-juvenile rhesus monkeys were rendered profoundly hypotensive for 0-, 15-, or 30-minute periods by means of infusion of trimethaphan camsylate. Blood pressure was then restored to prehypotensive levels with phenylephrine infusions. Respiratory gas tensions and pH of arterial blood were maintained within their normal limits throughout experimental and recovery periods. Animals either recovered and showed no sequelae or diet 12 to 48 hours later of cardiorespiratory difficulties, often accompanied by brain swelling. Brain injury and death occurred in 64% of cases when arterial blood pressure was maintained at 25 mm Hg for up to 30 minutes. Multifocal myoclonus, depressed electroencephalographic activity, rises in cisternal cerebrospinal (CSF) pressure, respiratory depression, and characteristic changes in serum and cisternal CSF glucose followed episodes of controlled hypotension. Hypoxia and acidosis occurring during insult or recovery periods rather than hypotension itself probably account for neuropathological sequelae described by others.

The use of the potassium titanyl phosphate (KTP) laser in neurosurgery.

The potassium titanyl phosphate (KTP) laser recently has been introduced for use in surgery, but as yet, no data have been published concerning the safety or efficacy of use of the KTP laser in neurosurgery. A series of patients treated with the KTP laser that revealed some practical advantages of this instrument over other lasers presently available is reported. The KTP laser has been designed with user safety in mind. In general, the KTP laser, with its angled, low-profile, lightweight hand pieces, was especially useful in anatomically confined locations, where a laser beam directed from an attachment operated with a joy stick mounted on the operating microscope would prove awkward. The KTP laser provided very good hemostasis. Certain large fibrous tumors were found to be more easily removed using a combination of the KTP laser and ultrasonic aspiration rather than with either instrument alone.

The histopathological effects of the CO2 versus the KTP laser on the brain and spinal cord: a canine model.

Because no data are available concerning the histopathological effects of the potassium titanyl phosphate (KTP) laser on central nervous tissue, a study was performed using a canine model to compare the histopathological effects of a commonly used laser (CO2) and the KTP laser on brain and spinal cord tissue. Exposed brain and spinal cord tissue were irradiated with 0.1-s pulses (x10), with spot sizes of 1 mm (in focus) over a range of 1 to 10 W. Wedge-shaped lesions were produced with the CO2 laser, while more blunt, semilunar-shaped lesions were produced by the KTP laser. The depth and width of the lesions were proportional to the energy applied. The lesions ranged in surface diameter from 0.6 to 1.3 mm for CO2 and 0.8 to 1.6 mm for KTP lasers, respectively. The depth of the lesions varied from 0.4 to 2.0 mm for CO2 and 0.3 to 1.1 mm for KTP lesions. Histopathologically, a central zone of tissue destruction and vaporization was surrounded by a zone of coagulative necrosis, in turn surrounded peripherally by a zone of pallor. CO2-induced lesions were histologically more hemorrhagic than KTP-induced lesions. In view of the histopathological findings, the KTP laser appears as safe as the CO2 laser in terms of tissue lateral thermal change (penetration) and tissue absorption. The additional hemostatic advantage observed clinically for the KTP laser is demonstrated histologically as well. Although the wavelength of the KTP and argon laser light are similar, the histopathological effects seem to be less pigment dependent. The KTP laser seems well suited for neurosurgery and has the versatility provided by a fiberoptic delivery system.

Alterations in neurological function in head-injured patients experiencing major episodes of sepsis.

More than 300 head injuries per year are evaluated by the neurotrauma team at the Maryland Institute of Emergency Medicine. Although most of the injuries follow motor vehicle accidents, a significant number also follow industrial accidents or acts of personal violence. Approximately 25% of patients with serious head injuries have associated episodes of sepsis--commonly because of other bodily injuries. We have identified a syndrome characterized by encephalopathy and/or accentuation of focal neurological dysfunction in head injury patients that presents during episodes of sepsis and that occurs in the absence of meningitis. Aggressive fever management alone does not reverse the encephalopathy. Neurodiagnostic studies reveal no focal changes. The intracranial pressure often remains normal or unchanged, and no improvement is evident after the empirical administration of standard doses f steroid or osmotic agents. The patient's neurological condition returns to base line once the sepsis has been eradicated. Ongoing investigations suggest an immunological basis for this abnormality.

Intraspinal extension of an air cyst of the lung: case report.

We report the diagnostic evaluation and treatment of a cystic paraspinal and epidural lesion originally thought to be a neurofibroma or an arachnoid cyst. Intraoperatively, the lesion was found to be an air cyst of the lung that was successfully ligated.

Bilateral cholesterol granuloma of the skull base: case report and review of the literature.

A unique case of bilateral cholesterol granuloma of the skull base and its treatment is presented. Cholesteatoma, a pathological entity often confused with cholesterol granuloma, is differentiated from cholesterol granuloma. Cholesterol granuloma is not rare. This tumor seems to derive from an inflammatory process at the skull base that results in bony erosion surrounding a cyst wall of inflammatory tissue. Neurological abnormalities reflect the location of the tumor in relation to the brain stem. Radiographically, the cyst wall enhances with the administration of i.v. contrast agent, and the center of the lesion is isodense with brain on computed tomography, unlike cholesteatoma. Magnetic resonance imaging characteristics are currently being defined. At operation, cholesterol granuloma consists primarily of a viscous fluid within a capsule of inflammatory tissue. Treatment requires establishing a pathway for drainage of the granuloma. The advantages of transsphenoidal, transclival drainage of such lesions are outlined.

Continuous suture method for microvascular anastomosis: technical note.

A continuous suture technique for microvascular end-to-side anastomosis was tested in an animal model. Twenty-five Wistar rats underwent carotid-to-carotid end-to-side anastomoses using the conventional interrupted suture technique, and another 25 animals underwent similar operations using a continuous suture method. Anastomosis patency, growth, and vessel clamp time during the operation were recorded. The continuous suture technique was found to have equivalent growth and patency figures and to be much faster than the interrupted suture method.

Intraoperative localization of subcortical brain tumors: further experience with B-mode real-time sector scanning.

Intraoperative ultrasonography is a potentially useful tool for the neurosurgeon faced with the task of finding and removing small subcortical brain tumors. With the B-mode real-time sector scan equipment now available, satisfactory images of the intracranial contents can be obtained. Others have reported obtaining images by applying the transducer directly to the dura mater or cortex. This carries the risk of pressure damage to the brain. Furthermore, the presence of acoustical noise in the region close to the transducer results in poor image resolution in the superficial region of the cortex. To circumvent these two problems, we have used a saline-filled cylinder placed over the craniotomy site to achieve acoustical coupling. This technique also increases the area of cortex visualized by the pie-shaped beam of the sector scan by separating the transducer from the brain surface.

Hypertrophic cervical osteophytes causing dysphagia. A review.

Problems associated with osteophytes of the spine are frequently called to the attention of the neurosurgeon. Diffuse idiopathic skeletal hyperostosis (Forestier's disease) is a common disorder of the spine; a small but important number of these patients present with spondylitic dysphagia. Anterior cervical decompression restores esophageal function. A patient with Forestier's disease is reported, and Forestier's disease is compared and contrasted with other disorders of the spine.

Changes in local cerebral blood flow following profound systemic hypotension.

The authors studied local cerebral blood flow in monkeys rendered hypotensive by infusion of a ganglionic blocking agent. Application of the 14C-antipyrine method demonstrated that the blood flow: 1) normally varies reproducibly from one structure to another within the brain; 2) appears at its lowest level in all structures during the early minutes of a rapid-onset hypotension; 3) maintains the same general rank order of blood flow rate during hypotension as was present during normotension; and 4) returns to supranormal levels immediately following the rapid restoration of blood pressure. The values for local cerebral blood flow remain close-to-normal in some animals and diminish significantly in others during late recovery from hypotension. The close-to-normal values accompany uncomplicated recoveries while the diminished values appear in those animals which became neurologically depressed. Areas of the brain considered predisposed to hypotensive injury did not exhibit depressions in blood flow rate during hypotension more markedly than did other brain areas. The present results are interpreted as strong evidence against the "border zone" hypothesis.

Cottonoid as an acoustical marker for intraoperative ultrasound scanning. Technical note.

The authors demonstrate the use of cottonoid as a marker for ultrasound localization of a subcortical tumor.

Effects of profound hypotension on cerebral blood flow during surgery for intracranial aneurysms.

The progression of changes in cerebral blood flow (CBF) and neurological status were measured in 12 patients in whom profound hypotension (mean arterial blood pressure (MABP): 30 to 40 mm Hg) was used during intracranial aneurysm surgery. Nine patients (Group I) showed autoregulation of CBF to an MABP of 40 to 50 mm Hg during surgery. None of these patients had arterial spasm preoperatively. Postoperatively, mild flow disturbances were noted at the site of retraction. Three Group I patients developed arterial spasm postoperatively, but there was no associated neurological deterioration. The remaining three patients (Group II) had impaired autoregulation during surgery, and CBF decreased by 35% to 65% at an MABP of 50 mm Hg. Two of these patients had angiography immediately before surgery, and both showed moderate to severe arterial spasm. Relatively severe flow disturbances were noted postoperatively at the site of retraction, and two patients developed ischemic deficits of late onset. Brain retractor pressure and the degree and duration of hypotension were equivalent in the two patient groups. There was no correlation between intraoperative reductions in CBF (to as low as 20 ml/100 gm/min in the unretracted hemisphere) and immediate postoperative neurological deficits. The use of halothane and mannitol and the relatively short duration of the flow reductions were suggested as factors contributing to the protection from ischemia that was observed. Arterial spasm was found to produce hemodynamic instability and reduced CBF, although neurological status was unaffected in the majority of patients. Patients with impaired autoregulation during surgery were at increased risk of delayed ischemic complications postoperatively, and showed characteristic flow disturbances at all three stages of their clinical course.

Unusual appearance of an en plaque meningioma of the cervical spinal canal. A case report and literature review.

STUDY DESIGN: A case report of a patient with cervical spinal cord and nerve root compression caused by a meningioma en plaque together with calcification of the posterior longitudinal ligament is presented,with a review of the literature. OBJECTIVE: To present the diagnosis of a calcified dural meningioma en plaque, with extradural extension into the ligamentum flavum, in a woman with cervical myelopathy and neuropathy. SUMMARY OF BACKGROUND DATA: This case demonstrates that the cervical spine can be involved in dural meningioma en plaque with calcifications, in a manner mimicking ossification of the ligamentum flavum, which has never been previously reported. METHODS: A patient presenting with cervical cord and nerve root compression caused by ossification of the posterior longitudinal ligament and a concurrent calcified dural meningioma en plaque was treated surgically and has made a gradual recovery. Imaging studies,surgical findings, and histopathologic evaluation were analyzed to support the diagnosis. RESULTS: At surgery, ossification of the posterior longitudinal ligament was noted, along with a calcified lesion involving the posterior cervical dura and the adjacent ligamentum flavum. A calcified meningioma was diagnosed by histopathologic examination of the dural-based lesion. CONCLUSION: Although previously not described, the diagnosis of calcified dural meningioma en plaque should be considered in all patients presenting with spinal cord and/or nerve root compression,even at cervical levels. Although ossification of the posterior longitudinal ligament and ossification of the ligamentum flavum are more common etiologies of partially circumferential spinal calcification, dural-based meningiomas with extension into the surrounding ligaments demand early recognition because they can be associated with a poorer prognosis.

The clinical application of hyperbaric oxygen therapy in spinal cord injury: a preliminary report.

While reports of the beneficial effects of hyperbaric oxygen therapy in experimental use appear in the literature, there have been no reports of clinical trials with hyperbaric oxygen therapy of acute spinal cord injury. A series of treatment protocols have thus been designed for treatment of acute spinal cord injury utilizing hyperbaric oxygen. The study has been in progress for the last two years and involved more than 50 patients; results from the therapy trial in 25 patients over the last 18 months will be presented in this preliminary report. Hyperbaric oxygen therapy was generally initiated approximately 7 1/2 hours following injury. Pretreatment and posttreatment motor scores were compared with those of patients given conventional therapy for acute spinal cord injury. Under these circumstances, patients receiving hyperbaric oxygen therapy appeared to recover more quickly, although their final motor scores were about the same as those of patients receiving conventional therapy. Thus, alter the time course of recovery, perhaps without altering the final neurological outcome.

Brain Contusion and Cervical Fracture in a Professional Boxer.

In brief: A 22-year-old professional boxer suffered a brain contusion associated with uncal herniation and cervical spine fracture in the ring. Unlike most catastrophic acute brain injuries in boxing, this one had a relatively favorable outcome. The authors discuss the role of emergency medical services in minimizing brain injury in boxing and the treatment of acute head trauma.

Treatment of hydrocephalus in patients with meningomyelocele or encephalocele: a recent series.

Meningomyelocele/encephalocele with associated ventriculomegaly can be treated as a single-stage procedure (i.e., both lesions treated simultaneous) or as two-stage procedures (i.e., each lesion treated at a separate time). A delay in closure of the meningomyelocele/encephalocele is associated with a higher incidence of ventriculitis/ventricular shunt infection-particularly when closure is performed more than 36 h after birth. In these situations, closure followed by surveillance cultures, appropriate antibiotics, ventricular drainage, and then delayed ventricular shunting seems more reasonable.

Alterations in cerebral blood flow produced by hypotension: a comparison of methods.

Alterations in cerebral blood flow produced by controlled episodes of hypotension were studied in 12 juvenile monkeys using a thermocouple techique. The qualitative changes observed agreed closely with those obtained from an earlier study employing [14C]antipyrine autoradiographic methods. The present study extends the validity of the earlier antipyrine investigations by means of the continuous recording. The advantages and disadvantages of the thermocouple technique are examined.

Syringomyelia: a neurological and surgical spectrum.

Because of the variation in the natural history, anatomy, surgical treatment, and follow-up periods reported to date, very few firm conclusions can be drawn regarding syringomyelia. With the advent of magnetic resonance scanning, cases of syringomyelia are being detected earlier and a better understanding of the disease has been facilitated. The authors report their personal experiences with 21 patients followed for 5-20 years. No single surgical procedure appears to predictably remedy any syrinx for more than a brief period of several years. Complete collapse of the syrinx does not eradicate all symptoms. Direct treatment of the syrinx makes intuitive sense for those syrinxes that do not communicate with the fourth ventricle. On the other hand, for syrinxes that are likely to communicate with the fourth ventricle, shunting of the ventricular system, particularly where ventriculomegaly exists (i.e., any degree of radiographic evidence of ventricular enlargement), should be considered initially. Procedures such as posterior fossa decompression may be necessary as dictated by the neurological condition of the patient. In the authors' experience, shunting procedures provided better improvement, with longer duration of improvement than with posterior fossa decompression. The timing and surgical details of posterior fossa decompression remain to be elucidated.

Changes in cortical impedance and EEG activity induced by profound hypotension.

Fourteen late juvenile monkeys were subjected to a single 30-min episodes of markedhypotension using an infusion of trimethaphan. Afterward, blood pressure was rapidly restored to and maintained at preinsult levels with an intravenous drip of phenylephrine (.02 mg/ml). The respiratory gas tensions and pH of the arterial blood weremaintained within normal limits at all times. During the 30-min episodes, the cortical electrical impedence increased by a mean of 27% while the EEG frequencies and amplitudes decreased by 47 and 30%, respectively. The impedance and EEG activity generally altered at the same time but inversely to one another, although, on restoration of blood pressure, the impedance recovered within minutes while the EEG activity returned to normal only after 1 h. The impedance values and EEG activity of those animals that eventually died began to diverge significantly from the values of theanimals that were to survive at about 2.5 h after restoration of blood pressure.