Biomedical subjects
Publications and source records attributed to P L Gildenberg.
A new head-positioning system has been developed to hold the head firmly during the performance of a computed tomograhic scan and to position the head reproducibly during repeat scans. This can be used to maintain the head in position during long scanning sessions, to relate a lesion to landmarks on scout views, to follow lesions in repeated scans over time, and to perform a variety of invasive procedures.
Twelve delayed or recurrent intracranial hematomas were seen in 340 patients with head injuries. Eleven of these hematomas were associated with clotting abnormalities suggesting disseminated intravascular clotting and fibrinolysis (DICF). Seven of 8 delayed traumatic intracerebral hematomas were associated with clotting abnormalities. Two of these were at ventriculostomy sites, which suggests an increased risk of bleeding in association with the insertion of ventricular catheters in patients with DICF. There were 2 delayed epidural hematomas, 1 under a fracture and the other on the side opposite a craniotomy that had been made to treat an intracerebral hematoma, and there were 2 postoperative epidural hematomas. No postoperative hematomas occurred in the absence of DICF. DICF is a major factor in the development of delayed and recurrent intracranial hematomas in patients with head injuries.
Kinetics of collagen synthesis and deposition were studied in the canine spinal cord, pia mater, and dura mater and in wounds of these tissues over the first 8 weeks. Little collagen is present in unwounded spinal cord compared with surrounding mesenchymal membranes. Collagen synthetic potential was found within the spinal cord, a tissue of neurectodermal origin. Rate of collagen synthesis per collagen content in the unwounded spinal cord was high. This synthetic rate was as high as that of wounds at their maximum collagen synthetic rates. Substantial deposition of collagen followed spinal cord wounding. Wounding the spinal cord, pia mater, and dura mater caused substantial elevations in rates of collagen synthesis in each tissue. These synthetic rates remained at maximum levels throughout the 8-week study, a prolonged period when compared with other wounded tissues previously studied. The role of mesenchymal tissue physiology in central nervous system wound healing is discussed. The potential value of these findings for further studies and for experimental manipulation of the healing process in spinal cord and central nervous system wounds is presented. Implications of these findings on the hypothetical relationship of scar to spinal cord and central nervous system regeneration are noted.
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Responses of muscle afferent nerve fibres to tendon taps of digital muscles in the human can be recorded with surface electrodes attached to the skin over the nerve at the wrist. Using an effectively monopolar recording method, a considerable improvement in signal amplitude is achieved with simultaneous reduction in mechanical artefacts using differential amplification techniques. The characteristics of the afferent waveform (latency and duration) are discussed in relation to the applied stimulus. The contribution to the afferent response from receptors other than in the muscle have been shown to be minimal. Afferent fibres from primary muscle spindle endings are thought to be the major contributors to the afferent waveforms recorded by this technique.
The effect of varying the fusimotor bias on the muscle spindle responses to light tendon taps has been studied in normal human volunteers using surface electrodes at the wrist for recording whole nerve activity. Reinforcement manoeuvres were found to increase the sensitivity of the afferent responses to the mechanical stimulus. Such sensitisation was found to be exhibited more commonly as a decrease in the latency of the peak of the afferent waveform than as an increase in amplitude. Increase in amplitude of the response was seen in cases where the subject was well relaxed and the test muscle quiescent. A change in furimotor drive was also achieved by asking the subjects to close their eyes voluntarily during the test, thus depriving themselves of the visual feedback. The results under these conditions were found to be variable, though showing considerable changes from control recordings. The effect of reinforcement manoeuvres may perhaps result in increasing the dynamic fusimotor drive. Such an effect may be simulated on occluding the blood supply to the test muscle since ischaemia produces an immediate rise in the rate of afferent discharge. The method of recording is suggested as a convenient technique for clinical use.
A new method is described to treat spasmodic torticollis with the implantation of a dorsal column stimulator at the C1--2 level or with transcutaneous stimulation. 22 patients were evaluated. 3 had sufficient relief to be treated with transcutaneous stimulation only. An additional 6 patients had surgically implanted dorsal column stimulators. It was empirically determined that a frequency of 800--1,100 Hz gave the best relief from torticollis. 1 patient had an excellent result; 3 have had good results; 1 had a fair result, and 1 had a poor result. An additional patient with dystonia musculorum deformans was considerably improved by the use of dorsal column stimulation.
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A survey of the number of neurosurgeons performing stereotactic and functional neurosurgery in the United States and Canada was conducted by questionnaire. Of the 637 respondents, 433 conducted either stereotactic or functional neurosurgery or both. The indications and number of stereotactic procedures done annually are presented. The number of neurosurgeons performing each of the various procedures is outlined, as well as the types of stereotactic apparatus and lesion employed.
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