Biomedical subjects
Publications and source records attributed to T L Hardy.
A computerized 3-D brachytherapy treatment planning program has been developed which simulates catheter trajectories, radioisotope seed positioning and percentage dosimetry zones about a catheter/seed array in relationship to CT or MRI images. The high activity 125I seed is used in this program. A visual and a non-linear mathematical optimization program will also be described.
A computerized anatomic atlas mapping technique has been developed and used to determine target sites for stereotactic thalamotomies. The digitized stereotactic atlases of Schaltenbrand and Bailey, Van Buren and Borke, and Schaltenbrand and Wahren are used in conjunction with an associated electrophysiological data base to determine the intended target site on MR images of the diencephalon. This mapping technique uses the 'Brierley and Beck' proportional hypothesis for thalamic nuclear determination. Target site determination by this method was found to be very accurate, and frequently the mere placement of the probe in the target site resulted in tremor cessation.
The implementation and use of a computerized whole-brain mapping system which can be used in conjunction with MRI, CT, angiographic and other brain imaging techniques is described. Three mapping systems based upon common reference structures about the third and fourth ventricular core of the brain are used in conjunction with internationally recognized nomenclature to create a normalized whole-brain mapping system according to the Talairach/Tournoux proportional grid technique.
Fourteen candidates for ablative seizure surgery underwent CT-guided, computer-assisted stereotactic depth electrode implantation and 21 underwent MRI-guided, computer-assisted implantation. A hand-held computer with no graphic capability was used for CT-guided procedures. A computer work station which included a high-resolution color graphics terminal with touchscreen interfacing and software capable of simulating targets and trajectories in single or multiple views was used for MRI-guided procedures. Previous phantom studies done with a 1.5-tesla MR scanner suggested acceptable localization error. Localizing information was obtained in 10 (71.4%) of 14 of the CT-guided implants and in 16 (76.2%) of 21 of MRI-guided cases. In the CT group, 7 (70%) were seizure-free and 8 (80%) were greater than 90% improved at 1 year follow-up. In the MRI group, 8 (80%) were seizure-free and 9 (90%) were greater than 90% improved at latest follow-up.
The author presents a method for the mapping of diencephalic somatotopography by the use of computerized image acquisition of CT and/or MRI scans with a computer graphics technique. Data gathered from exploratory stimulation and recordings during the normal course of stereotactic surgical procedures can then be used with this image acquisition and graphics technique for composing diencephalic somatotopographical maps.
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The oral administration of a suspension of N-phenylanthranilic acid (N-PAA), over the range of 0.5 to 2 mmol/kg for 14 consecutive days, caused a dose-related renal papillary necrosis (RPN), which involved no more than 30% of the medullary apex. This area of necrosis was no greater following daily doses of 3 and 5 mmol/kg of N-PAA for 14 days, but cortical degenerative changes were induced. The area of the necrotic lesion was greater in the left kidneys of individual rats than in the right kidneys. The apex-limited histopathological changes associated with the administration of low doses of N-PAA were not reflected by altered electrolyte or water homeostasis and only high doses of N-PAA caused significant changes. Urinary volume was significantly increased (in animals treated with 5 mmol/kg), whereas urinary osmolality (greater than 2 mmol/kg N-PAA), and Na+ (5 mmol/kg), K+ (5 mmol/kg), and Cl- (5 mmol/kg) excretion was decreased compared to controls. Blood urea nitrogen was increased at doses greater than 3 mmol/kg in association with cortical degenerative changes. When untreated rats were dosed orally with NH4Cl (400 mg/kg) there was a lag period between 0 and 2 hr (when no changes in H+ excretion occurred), but the urinary pH was depressed in the 2- to 4-hr collection period. Only those rats treated with the highest dose of N-PAA (5 mmol/kg) showed a significantly impaired urinary acidification after NH4Cl loading. There was, however, a statistically significant dose-related decrease in the excretion of Cl- following NH4Cl dosing, provided urine was sampled between 0 and 2 hr. These data highlight the failure of the commonly used renal function tests (such as urinary volume, osmolality, and electrolyte excretion) to reflect apex-limited RPN, unless cortical degenerative changes were also present. The dose-related depression of Cl- excretion in the 0- to 2-hr period following oral NH4Cl loading, suggests that appropriately timed sampling of this urinary anion could offer an improved criterion for the diagnosis of RPN.
The present study utilized EMG biofeedback in the treatment of functional bladder-sphincter dyssynergia, a learned incoordination of bladder and urethral sphincter activity during voiding. The condition is usually associated with a history of painful urination due to bladder infections, surgery, or harsh toilet training. The subject was an 8-year-old girl with chronic diurnal urinary frequency, urge incontinence, and nocturnal enuresis. Treatment consisted of intensive instruction in alternately tensing and relaxing her lower pelvic musculature, as well as relaxing during voiding. These exercises were accompanied by EMG biofeedback from perianal and perivaginal surface electrode sites. Home practice consisted of the tense-relax exercise, relaxation during voiding, and self-monitoring and record-keeping. There were 17 sessions over a period of 9 months. No medication was used. Marked reduction (to normal levels) in diurnal urgency and frequency occurred by the 3rd week of therapy, and complete recovery of normal function, including nocturnal continence without waking, occurred by the 13th therapy session, 5 months after therapy began. Follow-up 1 year after therapy revealed that these gains were being maintained. Pre- and posttherapy urodynamic studies corroborated the achievement of normal urinary function.
Intraspinal synovial cysts probably originate from herniation of synovium through a weakened facet joint capsule. The computed tomographic (CT) findings of such lesions were recently reported. An additional characteristic is gas within the cyst as demonstrated by CT. We postulate the source to be an adjacent diseased facet joint with a vacuum cleft with consequent dissection of gas into the cyst.
A computer graphics technique for computer-assisted stereotactic surgery is presented. The program is designed to aid the surgeon by presenting an on-line graphics display of stereotactic probes and electrodes superimposed on cross sections of the human brain stem. This technique simulates an otherwise blind surgical procedure on a graphics screen for use during surgery. An earlier system based around the DEC MINC-11 BA computer system has been used by the authors for the performance of stereotactic surgery with conventional ventriculography. This system has been upgraded and is now configured about an even more compact microprocessor-based hardware system with expanded graphics capabilities, which also allows its use with computerized tomography.
A review of the literature reveals that most chronic subdural empyemas occur within four to six months of the initial insult. It appears that only 1 case of a chronic subdural empyema, which occurred four years after extensive facial trauma, has been described. Our patient developed chronic subdural empyema thirteen years after drainage of a subdural hematoma. Current treatment modalities are reviewed.
Forty-nine children with complicated bacterial meningitis were studied. Thirteen had abnormalities on computed tomography compatible with the diagnosis of brain infarction; one had a brain biopsy with the histological appearance of infarction. Factors exist in childhood bacterial meningitis which are associated with the development of brain infraction.
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With the aid of a computer graphic display technique, data gathered from exploratory diencephalic recordings in 130 stereotactic operative procedures are presented to show the location and somatotopography of 'pressure'-evoked cellular responses. In addition, the variable position of these responses in relation to common diencephalic landmarks is presented. Our findings indicate that response points are more compact when related to a common posterior commissure (PC) and lie in a sickle-shaped zone 14-16 mm lateral to the midline and 2-8 mm rostral to anatomically the nucleus ventralis caudalis or the nucleus ventralis intermedius. Somatotopographically, face responses were medial to the leg.
With the aid of a computer graphic display technique, data gathered from exploratory diencephalic recordings in 130 stereotactic operative procedures are presented to show the differing topographical distribution of 'joint'- and 'muscle'-evoked cellular activity. In addition, the variable position of these responses in relation to common diencephalic landmarks is presented. Our findings indicate that response points lie in a sickle-shaped zone 14-19 mm lateral to the midline and 2-11 mm posterior to the midcommissural plane. This area correlates closely with the findings of others on the thalamic zone of 1A afferent projections and agrees with the anatomical position of the nucleus ventralis intermedius as plotted by others. When the response points are plotted against a common posterior commissure, a more compact grouping is obtained and 'muscle'- and 'joint'-evoked responses are noted to separate into different zones, with 'muscle' responses positioned slightly anterior and inferior to those for 'joint'. Somatotopographically, face responses were positioned posteriomedially and leg responses anterolaterally.
With the aid of a computer graphic technique, data gathered from exploratory diencephalic recording in 130 stereotactic procedures are presented to show the topography of 'bilateral-movement-evoked' thalamic cellular activity. Thalamic cells responding to bilateral voluntary extremity movement were found to occupy a thalamic zone rostral to the zone for 'muscle'- and 'joint'-evoked thalamic cellular activity.
Six Medtronic 1743 dual-channel cerebellar stimulators were implanted in 4 patients between September 1977 and January 1979. Evaluations were conducted in both a blind and nonblind fashion. Significant differences between the evaluations occurred. The operating surgeon, physical therapists, referring neurologist and the patients' families all overestimated the degree of improvement, compared to a blind evaluation by a noninvolved group of neurologists. The concomitant occurrence of significant complications raised serious questions of the advisability of cerebellar stimulation for cerebral palsy.
With the aid of a computer graphic technique, data gathered from exploratory stimulation of the diencephalon in 130 stereotactic operative procedures indicate that some sensory fibers in the capsule are parallel to motor fibers at basal thalamic levels and occupy a position medial to motor fibers. In addition, stimulus responses which probably represent thalamocortical projections from S II somesthetic thalamus were found to lie in a capsular zone rostral to the motor bundle. The organization of S I somesthetic thalamus was found to agree with the previous finding of Tasker et al. and some of these fibers project within the motor bundle to cortical motor areas.