Curtis A. Gleason

Stereotactic Localization (with Computerized Tomographic Scanning), Biopsy, and Radiofrequency Treatment of Deep Brain Lesions

In eight patients stereotactic biopsy of deep brain lesions was performed. Adequate tissue was obtained, and the information helped considerably in planning further therapy. No significant complications occurred in these patients. In three of the cases, the stereotactic coordinates were determined from the computerized tomographic (CT) scan. In one patient, after biopsy, stereotactic radiofrequency (RF) lesions in the tumor resulted in temporary improvement.

Suppression of an Epileptiform Type of Electrocortical Activity in the Rat by Stimulation in the Vicinity of Locus Coeruleus

Stimulation in the locus coeruleus, or in the vicinity of this nucleus or of its ascending tracts, could markedly suppress the appearance of epileptiform‐like ECoG bursts. The latter were i induced in rats by a subconvulsive dose of pentylenetetrazol. Electrode sites were identified histologically. A unilateral stimulus suppressed bursts bilaterally. An individual burst already in progress could be aborted, stopping within less than 0.5‐1 sec after onset of a stimulus train. The antiepileptiform actions occurred with no evidence of any desynchronizing effect of the stimulus on the resting ECoG; they appear to be different in sites of origin and nature from those reported for stimulation of the reticular activating system. It is proposed that stimulation of the ascending noradrenergic system in the brain stem may limit the development and spread of hyperexcitatory, epileptiform states.

Bladder acellular matrix graft: in vivo functional properties of the regenerated rat bladder

Abstract The purpose of this study was to determine whether the rat urinary bladder augmented by an acellular matrix graft can restore the bladders low-pressure reservoir function and preserve normal micturition. After partial cystectomy (>50%) and grafting with the bladder acellular matrix graft (BAMG), storage and voiding functions were monitored in 20 rats by means of a specially designed “micturition cage,” leak-point cystography, and cystometry. After 4 months, sections (n = 6) were examined histologically to evaluate regeneration of bladder wall components within the BAMG. Bladder capacity and compliance increased progressively and were significantly higher in the grafted animals than in controls (partial cystectomy only), and volumes per void were significantly higher than in either control or normal animals. At 4 months, the regenerated urothelium, smooth muscle, blood vessels and nerves within the BAMG were qualitatively identical to normal bladder wall. Augmentation cystoplasty with the homologous BAMG leads to morphologic and functional rat bladder regeneration, thus enhancing low-pressure reservoir function and preserving normal micturition.

Intraoperative Electrostimulation of Cavernous Nerve: Technique, Results and Limitations

PURPOSE We studied the feasibility of inducing penile erection intraoperatively by stimulation of the cavernous nerves. MATERIALS AND METHODS In 16 men undergoing retropubic radical prostatectomy and 6 undergoing penile surgery for venous leakage electrostimulation was applied to both sides of the prostatic apex (prostatectomy group) or the hilum of the penis (venous surgery group). RESULTS Electrostimulation produced visible erection in 8 of the 16 prostatectomy patients and an increase in intracavernous pressure in 5 of the 6 venous surgery patients. CONCLUSIONS Electrostimulation of the cavernous nerves intraoperatively to produce penile erection is feasible. However, the technique must be further refined to be clinically useful, that is to localize the neurovascular bundle in men undergoing prostatectomy.

TIME DEPENDENT SMOOTH MUSCLE REGENERATION AND MATURATION IN A BLADDER ACELLULAR MATRIX GRAFT: HISTOLOGICAL STUDIES AND IN VIVO FUNCTIONAL EVALUATION

PURPOSE We evaluated the time dependence of smooth muscle regeneration and restoration of in vivo functional properties in bladder augmented with a bladder acellular matrix graft. MATERIALS AND METHODS A total of 45 Sprague-Dawley rats underwent augmentation cystoplasty with a bladder acellular matrix graft. Two rats each were sacrificed at various intervals within the first 21 days and 6 each were sacrificed at 4, 8 and 12 weeks. This second group underwent preoperative and postoperative assessment of bladder function, including cystometry, electrostimulation and stimulation with ice water, potassium and carbachol, as well as labeling of the bladder wall by the injection of fluorescent microspheres. After sacrifice slides of the bladders prepared for hematoxylin and eosin, trichrome, KI67, vimentin, desmin, smooth muscle specific alpha-actin and fluorescent microspheres were evaluated. RESULTS Within 2 weeks the number of cells in the matrix as well as the proliferation index increased rapidly and then decreased gradually. Erythrocytes and inflammatory cells were found in the matrix within 2 to 4 days, followed by fibroblasts. A bladder host-to-matrix shift was evident by the appearance of microspheres in the matrix. Cell marker expression indicated the early appearance of vimentin and alpha-actin within the first 10 days. Distinct desmin expression was observed later, when the first smooth muscle cells were recognized. Functional evaluation revealed restored bladder function at 12 weeks. CONCLUSIONS The time dependent increase of muscle cell markers during smooth muscle cell regeneration in a bladder acellular matrix graft is concordant with the progressive restoration of bladder function. These results may support the bladder acellular matrix graft concept for clinical application.

Stimulation of Locus Coeruleus in Man

Stimulating electrodes were chronically implanted unilaterally (in 1975–1977) in the vicinity of the locus coeruleus (LC) in three patients, one with cerebral palsy-spastic quadriplegia, two with epil

The effect of magnetic resonance imagers on implanted neurostimulators.

This in‐vitro study was designed to investigate the safety of various implanted neurostimulators in magnetic resonance (MR) imagers. The effects of the static and changing magnetic fields and the radio frequency (RF) electromagnetic field generated by 0.35 and 2.5 T MR imagers on the voltage output of four models of implantable passive neurostimulafors and two models of implantable self‐powered neurostimulators was studied. The neurostimulators were mounted on a support and placed in the imagers. An oscilloscope monitored the voltages at the outputs of the neurostimulators. For an A very single‐channel stimulator, located at the isocenter, the amplitude of the output pulses induced by the 0.35 T imager was 6V; from a 1.5 T imager, it was 12 V. These amplitudes can cause discomfort and possible harm to a patient if the typical therapeutic value is 1–5 V. The amplitude of the stimulator receivers output decreased to relatively safe values beyond 40 cm from the isocenter. By contrast, there was no significant voltage output from the Medtronic SE‐4 receiver. For two models of self‐powered neurostimulators, the Medtronic Itrel and the Cordis MK If, the programmed stimulus parameters were not affected by the pulsed magnetic fields of the MR imagers. However, the RF fields at the isocenter heated the metal case of the stimulators. The rotational and linear forces produced by the fixed magnet on the Cordis MK II were judged to be too strong for a patient with this implant to be scanned. The study showed that patients with certain types of implanted neurostimulators can be scanned safely under certain conditions.

Bladder acellular matrix graft in rats: Its neurophysiologic properties and mRNA expression of growth factors TGF‐α and TGF‐β

To assess the neurophysiologic properties and molecular mechanisms of the bladder acellular matrix graft (BAMG), we performed cystometric and neurophysiologic studies in male Sprague‐Dawley rats (n = 46) at varying intervals. The animals were assigned to 3 groups: 1) normal, 2) partial cystectomy (>50%), and 3) partial cystectomy (>50%) and grafting with a BAMG of equal size. Additionally, matrix‐grafted and host bladders were processed for analysis of mRNA expression of transforming growth factor (TGF)‐α, TGF‐β1, TGF‐β2, and TGF‐β3 by reverse transcriptase polymerase chain reaction.

The human locus coeruleus and anxiogenesis

Electrical stimulation of locus coeruleus (LC), via permanently implanted electrodes with confirmed localization and effectiveness, did not elicit any subjective or behavioral manifestations of anxiety. This is evidence against the hypothesis that LC is a mediator of anxiogenesis in man.

Electrophysiological fundamentals of neurostimulation

SummaryThe parameters used in electrical stimulation of peripheral nerves depends on the specific characteristics of the tissue. The fundamental principles used to produce depolarization of the nerve and generation of the action potentials are reviewed. Stimulation parameters should be based on the knowledge of membrane characteristics. This will improve and preserve the efficacy of response with long-term stimulation.