Perfusion with lithium modifies neurophysiological responses in the CA1 region of the hippocampal slice preparation.

The effects of acute lithium exposure on extracellular electrophysiological responses in the CA1 region of the in vitro hippocampus were investigated. Field potentials were assessed while perfusing slices with normal media or media in which LiCl was substituted for NaCl in 30, 20, 10 and 2 mM amounts. Lithium concentration in the slice following 20 min perfusion with 20 mM lithium was determined to be about 14 mM. At the higher concentrations, lithium exposure depressed the presynaptic fiber volley and antidromic population spike. On the other hand, the population EPSP and orthodromic population spike were enhanced. No significant changes were found at 2 mM. The findings are compatible with one action of lithium being on the excitability of axons and synaptic terminals. Comparisons were drawn between previous studies involving chronic lithium exposure and the present results. In this acute preparation lithium effects, as reflected in the population EPSP, were in opposition to those found with chronic lithium exposure. Changes demonstrated in this preparation in fiber volley and antidromic population spike paralleled those found with chronic lithium exposure.

Primary pituitary carcinoma: a clinical pathological study.

A 60-year-old woman presented with a history of headache and rapidly progressive complete bilateral ophthalmoplegia. Her endocrine function was normal. Radiographic studies revealed signs of diffuse destruction of the sella turcica by a tumor without suprasellar extension. Biopsies of the lesion within the sphenoid sinus demonstrated the presence of a primary pituitary carcinoma; autopsy findings revealed metastatic deposits in the liver, kidney, and lung. The histological characteristics of these cells and the electron microscopic findings confirmed that the tumor can first manifest themselves by the rapid development of unilateral or bilateral ophthalmoplegia; this diagnosis should be considered in all individuals with such a syndrome.

Transantral transsphenoidal approach to the pituitary. Technical note.

The authors describe the technique of a transantral transsphenoidal approach to the sella turcica. The advantages and potential complications are discussed. This procedure may also be applicable when dealing with tumors of the skull base and orbits.

Tuberculous spondylitis. A report of six cases and a review of the literature.

Tuberculous spondylitis in the United States is a disease of decreasing incidence and, when the incidence is compared to that of developing nations, affects an older population. The thoracic and lumbar spine is most frequently involved, and in advanced disease several vertebrae may be destroyed with resulting significant morbidity and mortality. The usual clinical presentation consists of fever, back pain, and nonspecific systemic symptoms of varying duration. More advanced disease presents with neurological deficits, kyphotic deformities of the spinal column, and paravertebral cold abscesses. Treatment has changed in the past 50 years not only because of the introduction of highly effective anti-tuberculous chemotherapeutic agents, but also because of the development of new surgical approaches. Controlled studies comparing various surgical and more conservative therapeutic regimens have been conducted within the past decade. Despite these new data, controversy remains regarding the indications for surgical treatment, since anti-tuberculous chemotherapy alone is successful in a large proportion of cases. However, in situations where rapid loss of neurologic function is evident or in which progressive deterioration in spinal cord function continues in the face of apparently adequate drug therapy, it appears that anterior surgical decompression of the spinal cord is indicated to prevent irreversible neurologic deficits. Needle biopsy of bone lesions under fluoroscopic or computed tomographic control is essential in the initial evaluation of patients in order to obtain cultural confirmation of tuberculosis.

Compressive neuropathy as a complication of anticoagulant therapy.

Three cases of compressive neuropathy after anticoagulant therapy are reported. The first known description of ulnar and radial nerve involvement in this syndrome is provided. A review of the literature along with a discussion of some of the clinical features, the diagnosis, and the management of this entity are presented.

Electroencephalographic and behavioural effects of enflurane and halothane anaesthesia in the cat.

The effects of enflurane and halothane on the electroencephalogram (e.e.g.) were studied in 10 cats. Animals underwent at least 2 MAC-hours of anaesthesia with either agent, and the e.e.g. was monitored continuously. Arterial blood-gas tensions were maintained within normal limits. In addition, e.e.g. and behaviour were monitored during the period following anaesthesia, at fixed intervals, for 4 weeks. Despite the production of the central stimulatory effects of enflurane during anaesthesia, no animal demonstrated any central nervous system sequelae on any occasion following the anaesthetic.

Somatosensory-evoked potentials and slow oscillations in patients with cerebral lesions.

Somatosensory-evoked potentials induced by electrical stimulation of the median nerve were recorded in patients with intracerebral lesions and in normal controls and were studied by means of spectral analysis. The results shown that (1) there is a statistically-significant difference between spectral distributions obtained from normal subjects and those obtained from patients; (2) whereas in normal subjects, specific frequency components of the spectrum are enhanced (are "driven") at specific frequencies of stimulation, in patients with cerebral pathology, such driving is completely or partially abolished; and (3) these differences between normal subjects and patients become more evident at frequencies of stimulation that may vary from one patient to another; for this reason it is suggested that the use of a fairly wide range of frequencies of stimulation may be of great importance when such methods are employed in the evaluation of the functional state of the brain.

Xanthogranulomas of the third ventricle.

Two patients with xanthogranuloma of the 3rd ventricle are described. In each instance the tumor obstructed the interventricular foramina and caused dilatation of the lateral ventricles and signs of increased intracranial pressure; computerized tomography demonstrated the dense, nonenhancing lesion in the anterior 3rd ventricle. The pathogenesis of these rare tumors is discussed. These cases affirm the need to consider xanthogranuloma in the differential diagnosis of anterior 3rd ventricle tumors in adults.

Anticoagulants and intracerebral hemorrhage from an unsuspected meningioma.

A unique case of a patient with an undiagnosed convexity meningioma is presented. Hemorrhage into the tumor, following the administration of anticoagulant drugs for the treatment of thrombophlebitis, resulted in severe neurological defects and the eventual demise of the patient.

Corpus callosum and propagation of afterdischarge to contralateral cortex and thalamus.

The patterns of seizure spread were investigated in cats with experimental seizure foci in the motor cortex. Recordings were made with tungsten microelectrodes. When convulsive activity developed at the focus, there was activation of the ipsilateral thalamus before there was propagation of afterdischarge to the opposite hemisphere. Section of the corpus callosum did not prevent propagation of afterdischarge to the contralateral thalamus, and prolonged the circulation of abnormal activity between the cortex and ipsilateral and contralateral thalamus.

Cryptococcal infection of the central nervous system.

Two patients with cryptococcal infection of the central nervous system are described. The first presented with signs of an intracranial mass and was subsequently shown to have two lesions within the brain which were later identified as cryptococcal granulomata. Antifungal therapy did not eradicate the lesions; following their excision and continued therapy, the CSF became sterile however. The other patient had signs of a fulminant meningoencephalitis which initially were thought to represent the pathophysiological expression of an expanding brain tumor. These reports are used as a basis to review the various aspects of central nervous system cryptococcosis, particularly as they may relate to the neurosurgeon and the therapy of the disease.