John M. Van Buren

The ethmoid sinuses: A re-evaluation of surgical resection*

Summary The combined intracranial transfacial approach to the ethmoid, sphenoid, and frontal sinuses has been satisfactory in performing en bloc resection of cancer arising in or involving these anatomic areas. Fifty-four patients have been treated with this procedure, using the combined expertise of the neurosurgeon and the surgeon interested in the head and neck area. Two postoperative deaths have occurred, both attributed to meningitis. The long range postoperative morbidity is negligible, except as it relates to loss of the palate in all but eight patients and the orbital contents in thirty patients. The cumulative five year survival in this series of patients, forty-two of whom had failure of previous treatment, is 56 per cent. If the procedure is carried out with rigid attention to good surgical technic and the principles of en bloc tumor removal, this combined procedure has the following advantages: (1) allows accurate evaluation of the intracranial tumor extension, (2) protects the brain, (3) avoids cerebrospinal fistulization, (4) provides adequate hemostasis, (5) facilitates en bloc tumor resection, and (6) selectively conserves the orbital contents.

Cerebral Seizures of Probable Orbitofrontal Origin

Four patients with seizures of presumed temporal lobe origin are presented in whom a definite focal ictal onset in the orbitofrontal cortex was revealed during recording, either by chronically implanted electrodes or ECoG. In three cases automatisms occurred concomitantly with orbitofrontal activation without spread of paroxysmal activity into the temporal structures monitored. With eight additional cases of possible orbitofrontal epilepsy found on reviewing the literature, two subgroups emerge: (1) patients with primarily psychomotor‐type fits, and (2) patients with loss of consciousness, head and eye deviation, and generalized convulsions. Scalp EEGs, in patients on whom we have available data, manifested bilaterally synchronous, paroxysmal discharges which were bifrontal, frontopolar, or maximal in one anterior quadrant, with or without evidence of additional temporal lobe involvement. On the basis of anatomic and physiological studies, as well as our own electrographic data, it is felt that a posterior orbitofrontal and temporo‐limbic, or mesial orbitofrontal and parasagittal‐limbic relationship exists, within which autonomous epileptogenic zones may develop, with the ability to discharge directly and independently to subcortical centers, while eliciting similar clinical patterns.

Memory deficits during electrical stimulation of the speech cortex in conscious man

Abstract Cerebral zones supporting language and recent memory were mapped by electrical stimulation during neurosurgical treatment of epileptic patients. Stimulation of sites within the left posterior temporo-parietal cortex produced transient dysphasia. Continued stimulation of this cortical region also produced a retrograde type of verbal memory disorder, indicating a failure in the mechanism responsible for retrieval of stored information. In contrast, stimulation of the anterior temporal neocortex did not produce anomia and, instead, resulted in an anterograde memory loss, apparently caused by a defect in the verbal storage mechanism. Comparable stimulation of homologous areas on the right hemisphere did not interfere with object naming or immediate verbal recall.

Tumors of the paranasal sinuses: a therapeutic challenge

Cancer involving the ethmoid and sphenoid frontal sinus complex can be successfully eradicated by a combined transcranial and transfacial surgical dissection. Survival rates of 44 to 58 percent with a 3 percent hospital mortality rate in patients whose previous surgery or radiotherapy was largely unsuccessful suggest that this cosmetically acceptable surgical endeavor should be used more often by the head and neck surgeon in treating paranasal sinus cancer. Utilizing the principles of antibiotic prophylaxis, strict attention to principles of tumor removal and surgical technique, and the talents of the combined surgical and neurosurgical team, this aggressive surgical approach to the paranasal sinuses can be safely and successfully carried out. The approach described herein has the following advantages: it allows accurate evaluation of intracranial tumor extension while protecting the intracranial contents, it essentially avoids cerebrospinal fistulization, it provides adequate exposure for hemostasis, facilitates en bloc tumor resection, selectively conserves the orbital contents, and provides patient survival rates up to 58 percent for paranasal cancer that involves the ethmoid and sphenoid frontal sinus complex.

Memory and perceptual deficits during electrical stimulation in the left and right thalamus and parietal subcortex.

Mechanisms for perception and memory were probed by electrical stimulation via chronic electrodes in the human thalamus. Stimulation within the left pulvinar nucleus induced transient dysphasia and a retrograde loss in recent memory for verbal memoranda. In contrast, comparable stimulation of the right pulvinar failed to disrupt verbal behavior and, instead, disabled the mechanism for discrimination and recognition of complex visual patterns. The findings suggest that an asymmetry in the functional organization of linguistic and nonverbal processes appears to exist at the level of the lateral thalamus. The hypothesis is advanced that the pulvinar scans incoming sensory traces and searches long-term memory registers for appropriate cues and labels.

Significance of Purkinje cell density in seizure suppression by chronic cerebellar stimulation

Cerebellar biopsy specimens were obtained at the time of cerebellar electrode installation in three epileptic patients. Cerebellar autopsy specimens also were examined from four epileptic patients and from five patients without epilepsy or neurologic disease. All specimens from seizure patients showed isomorphic gliosis of the cerebellar cortices. Significantly lower Purkinje cell densities were found in epileptic patients as compared with nonepileptic control patients. Our two epileptic patients showing marked Purkinje cell loss before cerebellar stimulation appeared to have better seizure control during stimulation than the patient who had only mild reduction in Purkinje cell density. These data suggest that augmentation of Purkinje cell inhibitory discharges is not the dominant mechanism for seizure suppression during cerebellar stimulation. Comparison of cerebellar specimens obtained during electrode installation with those obtained later during electrode revisions may have prognostic significance.

Potassium clearance and reactive gliosis in the alumina gel lesion.

Potassium accumulation or impaired potas‐ sium clearance has been hypothesized to contri‐ bute to epileptogenesis in gliotic epileptogenic foci. To test this hypothesis, potassium clear‐ ance rates following direct cortical stimulation were measured in the cortex of monkeys ren‐ dered epileptic by the injection of alumina gel into the motor area. Reactive gliosis at the sites in which potassium clearance was measured was then quantitated histologically and compared with potassium clearance rates. Dense gliosis was associated with slowed potassium clear‐ ance, although the base‐line potassium level ap‐ peared no different in actively epileptogenic areas or gliotic areas compared with normal areas. Possible mechanisms and significance of slowed potassium clearance in the alumina focus are discussed.

Cerebrospinal fluid norepinephrine alterations during electrical stimulation of cerebellar, cerebral surfaces in epileptic patients.

Lumbar cerebrospinal fluid norepinephrine concentrations were determined by radioenzymatic assay in five epileptic patients receiving double-blind cerebellar stimulation and in three epileptic patients with subdural cerebral surface electrodes. Mean CSF norepinephrine levels were significantly elevated by chronic cerebellar stimulation and significantly depressed after intermittent cerebral cortical stimulation. Lumbar CSF cyclic adenosine monophosphate levels determined by radioimmunoassay were not significantly altered by either cerebellar or cerebral surface stimulation. Our study suggests that (1) electrical stimulation of the anterodorsal cerebellum in man evokes alterations in noradrenergic metabolism. Cerebellar stimulation-induced elevations in norepinephrine may inhibit cerebellar, cerebral, and spinal neuronaf activity. In addition, (2) noradrenergic responses to brain surface stimulation may exhibit regional specificity, and (3) noradrenergic alterations evoked by cerebral surface stimulation may not mimic those induced in isolated brain preparations.

Elevations in cerebrospinal fluid norepinephrine during unilateral and bilateral cerebellar stimulation in man.

Lumbar cerebrospinal fluid (CSF) norepinephrine concentrations determined by radioenzymatic assay in four epileptic patients were significantly higher during either chronic unilateral or bilateral cerebellar stimulation than those determined after a 7-day period without stimulation. The mean CSF norepinephrine levels noted during these two modes of cerebellar stimulation were not significantly different. The percentage of increase in CSF norepinephrine in one patient receiving 200/sec stimulation was 3 times higher than those noted in the three patients undergoing 10/sec stimulation. These evoked alterations in norepinephrine metabolism may relate to the reported modulation of spasticity and cerebral neuronal excitability during chronic cerebellar stimulation. Lumbar CSF cyclic adenosine monophosphate levels determined by radioimmunoassay were not significantly altered by either mode or frequency of cerebellar stimulation.

Quantitative Testing and its Usefulness in the Evaluation of Therapy in Neurological Diseases

Clinical neurologists and neurosurgeons are beginning to realize the usefulness of quantitative testing batteries to augment the qualitative measurements of the standard neurological examination in ev