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Biomedical subjects

A G Shetter

Publications and source records attributed to A G Shetter.

28 records · Page 2Linked to original sources
PubMed1985

Computed tomography in cases of coccidioidal meningitis, with clinical correlation.

Cranial computed tomographic (CT) scans of 22 patients with coccidioidal meningitis were reviewed and their clinical course was analyzed. Abnormalities of the ventricular system or the basilar cisterns or both were present in 16 instances. Although it is not a definitive diagnostic tool, the CT scan is helpful in suggesting a diagnosis of coccidioidal meningitis and in predicting the prognosis of patients affected by the disease.

Adolescent↗
PubMed1983

Scarring around cervical epidural stimulating electrode.

Scarring around the electrically stimulating electrodes has been of concern since dorsal column stimulation was introduced. This concern resurfaced in the days of cerebellar electrodes and, with the advent of epidural stimulating techniques for the control of pain and spasticity, it again arises as a potential problem. We present a patient who underwent the placement of a C-2-C-4 electrode to treat torticollis; 3 months later, a mild spastic quadriparesis developed and the stimulation became ineffective. At reexploration, dense scar surrounded the electrode and confined the cervical spinal cord. With microdissection techniques, the scar was removed from the dura mater and the dura began to pulsate freely. The quadriparesis reversed. Examination of the scar tissue microscopically showed linearly arrayed fibroblastic nuclei, and we are uncertain whether the exuberant fibroblastic response is a response to electrical stimulation, the materials used in the electrode, or some technical aspects of the operation.

Adult↗
PubMed1983

Comparative study of neuroma formation in the rat sciatic nerve after CO2 laser and scalpel neurectomy.

Recent reports have suggested that peripheral neurectomy with the CO2 laser may be effective in preventing subsequent neuroma formation. To study this question further, we performed bilateral sciatic nerve sections in 31 rats using a steel scalpel on one nerve and a CO2 laser on the opposite side. The animals were killed 30 days after neurectomy and specimens were removed for gross observation, light microscopy, and electron microscopy. Axon composition studies were carried out in selected animals and axon diameter histograms were prepared. Well-formed neuromas were present in nerves transected by both the scalpel and the CO2 laser. The scalpel neuromas were characterized by a greater degree of interfascicular collagen deposition and perineurial cell proliferation. Laser neuromas demonstrated less perineurial compartmentalization and scar tissue formation. In addition, a foreign body reaction with multinucleated giant cells surrounding carbonaceous debris was seen that was not present in the scalpel neuromas. Analysis of axon composition studies revealed that both neuromas had a greater density of axons and a higher percentage of small diameter myelinated and unmyelinated axons as compared to control nerves. Laser neuromas had more axons per unit area than scalpel neuromas, but the percentage composition of axons was very similar in the two groups. We could find no evidence in the rat sciatic nerve model that CO2 laser neurectomy is less likely to result in neuroma formation than is conventional scalpel neurectomy.

Animals↗
PubMed1982

Intraoperative monitoring of brain-stem auditory evoked potentials.

Intraoperative brain-stem auditory evoked potentials (BAEP's) were monitored in 46 patients undergoing intracranial surgery for a variety of pathological conditions to determine whether this technique was capable of providing useful information to the operating surgeon. Intraoperative BAEP's were unchanged throughout surgery in 34 patients (74%), and these individuals had no postoperative hearing deficits. Four patients (9%) developed an abrupt ipsilateral loss of all waveform components beyond Wave I and had postoperative evidence of a pronounced hearing loss in the affected ear. An additional patient demonstrated BAEP loss contralateral to the side of surgery, and this was associated with subsequent signs of severe brain-stem dysfunction. Seven patients (15%) developed intraoperative delays of BAEP waveform latency values, but maintained recognizable waveforms beyond Wave I. Postoperatively, their hearing was either normal or mildly impaired, and there were no indications of other brain-stem abnormalities. This group represents the individuals who may have been benefited by evoked potential monitoring, since corrective surgical measures were taken when latency delays were observed. Intraoperative BAEP's can be reliably and routinely recorded in an operating room environment. They provide a good predictor of postoperative auditory status, and may have prevented permanent neurological deficits in a small segment of patients by alerting the surgeon to potentially reversible abnormalities.

Brain Diseases↗
PubMed1979

Relative cerebral glucose metabolism evoked by dental-pulp stimulation in the rat.

Electrical stimulation of dental pulp is widely acknowledged to produce a sensation that is predominantly or exclusively noxious in character. The authors report the pattern of local cerebral glucose utilization evoked by dental-pulp stimulation in the barbiturate-anesthetized rat, using the [14C]2-deoxyglucose method of Sokoloff. Autoradiographs were prepared from cryostat-cut brain sections of animals given an intravenous pulse of [14C]2-deoxyglucose and sacrificed after 45 minutes of continuous bipolar stimulation of the incisor tooth pulp. Areas of high optical density on the autoradiographs identified brain regions where glucose consumption, and hence functional activity, was maximal. Stimulus-related increases in glucose utilization were seen ipsilaterally in an uninterrupted column from the lower levels of trigeminal nucleus caudalis to the rostral extent of the main sensory nucleus. Mandibular incisor pulp stimulation yielded increased deoxyglucose uptake in relatively restricted dorsal portions of the nuclei, while maxillary pulp stimulation produced a more extensive area of uptake ventrally. Elevated deoxyglucose uptake was also seen in the contralateral ventrobasal thalamus and sensory cortex with maxillary, but not mandibular, pulp stimulation. No changes in metabolic activity were detected in extralemniscal or limbic structures. These initial results suggest that the [14C]2-deoxyglucose method may be a useful means of mapping central structures involved in nociception.

Animals↗
PubMed1977

Closed needle biopsy in the diagnosis of intracranial mass lesions.

A retrospective study was performed on 54 patients with intracranial mass lesions who underwent closed needle biopsy using freehand and stereotactic biopsy techniques. A diagnosis of brain neoplasm was established in 44 of 54 patients, and nonneoplastic abnormalities were discovered in an additional six cases. Permanent neurologic worsening was noted in two instances following biopsy, and a single patient died as a result of the procedure. Closed needle biopsy, particulary when done stereotactically, appears to be a resonably safe and efficacious means of establishing a tissue diagnosis in carefully selected patients suspected of harboring a deep-seated supratentorial cerebral neoplasm.

Adolescent↗
PubMedDate not supplied

Monitoring of intraoperative auditory brain stem responses.

We believe that our initial experience establishes the fact that ABRs can be routinely and reliably performed in an operating room environment. There was no added risk to the patient, and operative delays were minimal. We did note transient fluctuation in latency values up to 1.5 msec. These changes would revert to baseline levels within five to ten minutes. Changes noted during drilling were probably related to the random noise produced. Case 3 was worrisome in that hearing was lost after maintenance of the ABRs during the surgical procedure. Evidently the vestibule was damaged, and a labyrinthitis caused the hearing loss. We feel that this procedure will be most useful in those situations in which the cochlear nerve and blood vessels are at risk. Such procedures as acoustic tumor removal with attempts to preserve hearing, vestibular nerve sections, and facial nerve problems in the IAC should be routinely monitored. Further experience will, of course, be most helpful in explaining and recognizing these changes.

Adult↗