Biomedical subjects
D C Taylor
Publications and source records attributed to D C Taylor.
Surgical treatment of drug-resistant epilepsy due to mesial temporal sclerosis. Etiology and significance.
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The metabolism of 16 alpha-ethylprogesterone by rat liver in vitro.
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Clinical, socio-economic, and psychological changes after temporal lobectomy for epilepsy.
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Driving after temporal lobectomy for epilepsy.
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Studies on carbohydrate metabolizing enzymes. XVI. Specificity of laminaribiose phosphorylase from Astasia ocellata.
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A case of craniopharyngioma presenting as Korsakov's syndrome.
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Carotid artery duplex scanning.
Duplex scanning of the carotid arteries combines B-mode ultrasound and Doppler ultrasound within a single instrument, thus providing both anatomical imaging of the vessel and flow velocity information. Combining these two unique aspects of ultrasound overcomes many of the individual limitations of each and provides improved noninvasive diagnosis of cerebrovascular disease. The Doppler signal is analyzed using fast Fourier transform methods and displayed as a spectral waveform. Assessment of the presence and severity of vascular disease is based primarily on Doppler information and the B-mode image of the vessel serves mainly as a road map to guide the placement of the pulsed Doppler sample volume. The parameters used to classify severity of disease include peak systolic frequency, degree of spectral broadening, end diastolic velocity, and overall shape of the waveform. Using these features, stenosis at the carotid bifurcation is classified into six categories: (A) none, (B) 1%-15% diameter reduction, (C) 16%-49% diameter reduction, (D) 50%-79% diameter reduction, (D+) 80%-99% diameter reduction, and (E) complete occlusion. These methods have a sensitivity of 99% and a specificity of 84% when compared with angiography. The clinical applications of carotid artery duplex scanning are discussed with particular reference to (1) patients with cerebrovascular symptoms, (2) asymptomatic cerebrovascular disease, (3) follow-up of carotid endarterectomy, and (4) cerebrovascular research. Patterns of use of duplex scanning in current practice and potential future applications are discussed.
The study of storage lipid biosynthesis using microspore-derived cultures of oil seed rape.
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What kind of thing is 'being clumsy'?
The term 'clumsy' is used both as a colloquial pejorative and as a specific diagnostic entity. The meaning of the word and the possible means by which a child may come to be regarded as clumsy are discussed. The implications for management are considered.
Operative versus nonoperative management of asymptomatic high-grade internal carotid artery stenosis: improved results with endarterectomy.
In a 4-year period, 129 asymptomatic high-grade (80-99%) internal carotid artery stenoses were identified in 115 patients. Because we previously demonstrated a strong relation between degree of carotid stenosis and subsequent development of ipsilateral related events (stroke, transient ischemic attack, and carotid occlusion), we changed our previous policy and began to offer carotid endarterectomy to good surgical risk patients referred to us with asymptomatic high-grade carotid stenosis. A total of 56 carotid endarterectomies were performed while 73 lesions were followed nonoperatively. Operated and nonoperated groups were similar with regard to age, prevalence of hypertension, cardiac disease, diabetes, and aspirin use. Life table analysis to 24 months revealed a higher rate of stroke (19 vs. 4%, p = 0.08), transient focal neurologic deficits (28 vs. 5%, p = 0.008), and carotid occlusion (29 vs. 0%, p = 0.003) in the nonoperated group. Eight of the 9 strokes in the nonoperated group occurred within 9 months of diagnosis of the high-grade lesion; none were preceded by a transient ischemic attack. There was 1 perioperative stroke (1.8%) but no in-hospital operative deaths and no difference in the late death rates of the two groups. This suggests that the preservation of neurologic status in patients with asymptomatic high-grade internal carotid artery stenosis can be improved by carotid endarterectomy.
Recurrent shoulder instability after open reconstruction in athletes involved in collision and contact sports.
The purpose of this study was to evaluate the incidence of recurrent instability in a group of young athletes who underwent open shoulder stabilization with a modified Bankart repair and anterior capsulorrhaphy. Recurrent dislocation was defined as an instability episode resulting in complete dislocation requiring manual reduction. Recurrent subluxation was defined as the subjective history of the shoulder "slipping or popping out" or pain and apprehension that caused cessation of athletics for at least 1 day. Sixty-six patients (64 men and 2 women) were included in the study. A collision sport precipitated instability in 53 patients and a contact sport in 13. The average follow-up was 47 months (range, 24 to 72). The average American Shoulder and Elbow Surgeons score was 95 points (range, 71 to 100). The average Rowe score was 80 points (range, 40 to 100). Two patients had experienced recurrent dislocation after surgery (3%). Eight patients (12%) had rare (fewer than three) episodes of postsurgical subluxation. Five patients (8%) had multiple recurrent subluxations after surgery. Postsurgical recurrent instability was significantly associated with preoperative episodes of subluxation. However, all patients with rare subluxation had an excellent functional result.
A prospective study of modified Ottawa ankle rules in a military population. Interobserver agreement between physical therapists and orthopaedic surgeons.
To determine the necessity of ankle and foot radiographs, we used modified Ottawa Ankle Rules to evaluate all cadets seen with an acute ankle or midfoot injury at the United States Military Academy. This scoring system determines the need for radiographs. Each patient was independently examined and the decision rules were applied by a physical therapist and an orthopaedic surgeon. Ankle and foot radiographs were obtained for all subjects. Sensitivity, specificity, and the positive predictive value were calculated in 153 patients. There were six clinically significant ankle fractures and three midfoot fractures, for a total incidence of 5.8%. For physical therapists, the sensitivity was 100%, the specificity for ankle injuries was 40%, and the specificity for foot injuries was 79%. For orthopaedic surgeons, the sensitivity was also 100%, the specificity for ankle injuries was 46%, and the specificity for foot injuries was 79%. Interobserver agreement between the orthopaedic surgeons and physical therapists regarding the overall decision to obtain radiographs was high, with a kappa coefficient value of 0.82 for ankle injuries and 0.88 for foot injuries. There were no false-negative results. Use of the modified Ottawa Ankle Rules would have reduced the necessity for ankle and foot radiographs by 46% and 79%, respectively.
Prospective evaluation of arthroscopic stabilization of acute, initial anterior shoulder dislocations in young athletes. Two- to five-year follow-up.
From March 1992 to November 1998, 57 patients sustained 58 acute, initial, traumatic anterior shoulder dislocations at the United States Military Academy. Six patients selected nonoperative treatment. Three patients underwent primary open repair after diagnostic arthroscopy revealed no Bankart lesion amenable to repair with the bioabsorbable tissue tack. The remaining 48 patients with 49 anterior dislocations were treated with arthroscopic primary repair. There were 45 men and 3 women with an average age of 20 years (range, 17 to 23) and an average follow-up of 37 months (range, 24 to 60). The average Rowe score was 92 (range, 30 to 100). The average single assessment numeric evaluation patient rating was 95.5% (range, 50% to 100%). The average Short Form-36 score (physical function) for the stable shoulders was 99 (range, 95 to 100). Forty-three shoulders remained stable (88%). There were six failures (12%). Factors associated with failure included a history of bilateral shoulder instability, a 2+ sulcus sign, and poor capsulolabral tissue at the time of repair. All patients with stable shoulders returned to their preinjury levels of athletic activity. With follow-up of 5 years, we have observed significantly better results compared with nonoperative treatment in young, active adults at the United States Military Academy.
Viscoelastic properties of muscle-tendon units. The biomechanical effects of stretching.
Most muscle stretching studies have focused on defining the biomechanical properties of isolated elements of the muscle-tendon unit or on comparing different stretching techniques. We developed an experimental model that was designed to evaluate clinically relevant biomechanical stretching properties in an entire muscle-tendon unit. Our objectives were to characterize the viscoelastic behavior of the muscle-tendon unit and to consider the clinical applications of these viscoelastic properties. Rabbit extensor digitorum longus and tibialis anterior muscle-tendon units were evaluated using methods designed to simulate widely used stretching techniques. Additionally, the effects of varying stretch rates and of reflex influences were evaluated. We found that muscle-tendon units respond viscoelastically to tensile loads. Reflex activity did not influence the biomechanical characteristics of the muscle-tendon unit in this model. Experimental techniques simulating cyclic stretching and static stretching resulted in sustained muscle-tendon unit elongations, suggesting that greater flexibility can result if these techniques are used in the clinical setting. With repetitive stretching, we found that after four stretches there was little alteration of the muscle-tendon unit, implying that a minimum number of stretches will lead to most of the elongation in repetitive stretching. Also, greater peak tensions and greater energy absorptions occurred at faster stretch rates, suggesting that the risk of injury in a stretching regimen may be related to the stretch rate, and not to the actual technique. All of these clinically important considerations can be related to the viscoelastic characteristics of the muscle-tendon unit.
Abdominal musculature abnormalities as a cause of groin pain in athletes. Inguinal hernias and pubalgia.
There has been increasing interest within the European sports medicine community regarding the etiology and treatment of groin pain in the athlete. Groin pain is most commonly caused by musculotendinous strains of the adductors and other muscles crossing the hip joint, but may also be related to abdominal wall abnormalities. Cases may be termed "pubalgia" if physical examination does not reveal inguinal hernia and there is an absence of other etiology for groin pain. We present nine cases of patients who underwent herniorrhaphies for groin pain. Two patients had groin pain without evidence of a hernia preoperatively (pubalgia). In the remaining seven patients we determined the presence of a hernia by physical examination. At operation, eight patients were found to have inguinal hernias. One patient had no hernia but had partial avulsion of the internal oblique fibers from their insertion at the public tubercle. The average interval from operation to return to full activity was 11 weeks. All patients returned to full activity within 3 months of surgery. One patient had persistent symptoms of mild incisional tenderness, but otherwise there were no recurrences, complications, or persistence of symptoms. Abnormalities of the abdominal wall, including inguinal hernias and microscopic tears or avulsions of the internal oblique muscle, can be an overlooked source of groin pain in the athlete. Operative treatment of this condition with herniorrhaphy can return the athlete to his sport within 3 months.
Abdominal musculature abnormalities as a cause of groin pain in athletes.
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Syndesmosis sprains of the ankle. The influence of heterotopic ossification.
A retrospective study of 50 syndesmosis sprains in 44 football players was performed. Five patients (6 ankles) were lost to follow-up, allowing review of 44 injuries. Average follow-up was 47 months. The patients were evaluated for recurrent injury, overall ankle function, and for persistent ankle symptoms, including stiffness, pain, limping, and swelling. Follow-up radiographs of the injured ankle were obtained in 22 patients. The average return time to full activity was 31 days. Pain with pushing-off was a major factor preventing return to activity. At final followup, 36% of the patients complained of persistent mild to moderate stiffness of the ankle. Twenty-three percent had mild to moderate pain, usually with activity. One patient had a mild limp with activity, and 18% of the ankles had persistent mild to moderate swelling. Ankle function was rated as good to excellent in 86%. All patients with fair results had recurrent ankle sprains. There were no poor results. Eleven of the 22 patients with follow-up radiographs developed heterotopic ossification within the interosseous membrane, but no patient developed a frank synostosis. The patients with heterotopic ossification required an average of 11 days more recovery time than those without ossification. There was no significant difference between the 2 groups' ultimate ratings of ankle function or ankle symptoms, but the ankles with heterotopic ossification were associated with more recurrent lateral ankle sprains. We conclude that syndesmosis sprains require a longer recovery period than other types of ankle sprains. Most of these injuries showed good to excellent ankle function after recovery, unless there was a recurrent ankle sprain.2+ formation of heterotopic ossification.