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Biomedical subjects

C W Cummings

Publications and source records attributed to C W Cummings.

At least 55 records · Page 3Linked to original sources
PubMed1986

Assessment of facial reinnervation by use of chronic electromyographic monitoring.

The study of muscle reinnervation has been difficult because of lack of an accurate, reproducible method to monitor return of function. Visual assessment relies on subjective interpretation. Histology provides anatomic, not functional, information. Electromyography and anatomic tracing have been most effective in evaluating physiologic return of muscle function. It has been difficult to assess the timing of functional return electromyographically because measurements are intermittent and electrode placement varies. A method was designed to allow long-term monitoring of electromyographic (EMG) activity in the facial musculature of the rabbit. Sixteen rabbits were monitored for at least 1 month or until return of normal EMG activity was identified. Various levels of injury (nerve crush, transection without repair, and transection with immediate end-to-end anastomosis) were evaluated. EMG evidence of reinnervation was seen in all animals with nerve crush injuries as well as those with anastomoses. Physiologic continuity of the nerves was then evaluated by retrograde transport of horseradish peroxidase. All muscles showing return of EMG activity had uptake of HRP into the appropriate brain stem motor neurons. The denervated muscles showed no HRP uptake. The information gained in this study shows potential for use of this technique in comparing functional return of muscle activity between different reinnervation methods.

Animals↗
PubMed1986

Venous outflow obstruction in myocutaneous flaps: changes in microcirculation detected by the perfusion fluorometer and laser Doppler.

The effects of venous occlusion on the perfusion of porcine myocutaneous groin flaps were studied by means of the laser Doppler and the dermofluorometer. A consistent decrease in fluorometer readings following venous clamping with rebound to original or greater levels after unclamping was noted. A similar pattern was noted in laser Doppler studies. However, flow as measured by the Doppler remained significant (greater than 100 mV) even with venous outflow occlusion. It is hypothesized that the Doppler is more prone than the dermofluorometer to reflect non-nutritive flow in the flap during the early period following flap construction and, therefore, may be less accurate in the evaluation of actual flap microperfusion. The fluorometer was determined to be the more desirable instrument in monitoring the microcirculatory status of myocutaneous flaps during the immediate period after flap elevation and transposition.

Animals↗
PubMed1986

Preliminary observations after facial rehabilitation with the ansa hypoglossi pedicle transfer.

Facial paralysis is a very disabling condition, both functionally and cosmetically. Despite the different methods of facial reanimation that have been described, there is no single method that will restore normal facial tone and motion. Of the methods available, primary neurorrhaphy is probably the most effective. The recovery period, however, is prolonged and, as a result, muscle tone and bulk may be lost. The hypoglossal-facial anastomosis is also a very reliable and effective technique but requires necessary interruption of both major cranial nerve trunks. Transfer of a neuromuscular pedicle (based on the ansa hypoglossi) has been offered as a method of facial reanimation that involves neither prolonged recovery nor interruption of the major cranial nerve functions. The application of this technique for reinnervation of a paralyzed larynx was first described by Tucker in 1970, and the technique was applied to facial muscle (in animal models) in 1977. The effectiveness of this technique--and its application in the management of facial paralysis in the human patient--remains controversial. We report our experience with a series of six patients who underwent neuromuscular pedicle transfer in conjunction with other more conventional methods of facial reanimation. The function of the pedicle and its contribution to the overall facial rehabilitation were assessed clinically and electromyographically. Factors influencing the success of the procedure and clinical and experimental evidence to support its application are discussed. While our experience with this technique is limited, it would appear that the neuromuscular pedicle transfer may play a useful adjunctive role in reanimation of the face in selective cases of facial paralysis.

Adult↗
PubMed1986

The effect of alpha-adrenergic stimulation and blockade on perfusion of myocutaneous flaps.

A porcine myocutaneous flap model was utilized to assess the development of denervation adrenergic hypersensitivity and to determine the effects of the alpha-adrenergic blocking agent--phenoxybenzamine--on flap blood perfusion. During intravenous administration of norepinephrine, blood flow to the flaps and control skin was monitored simultaneously, using laser Doppler velocimetry and dermofluorometry. A relative decrease in myocutaneous flap blood flow, as compared to control skin in response to norepinephrine infusion, was observed at between 2 and 7 days following flap elevation. This is the same time period during which norepinephrine content of skin flaps is diminished, and suggests development of an increased sensitivity to adrenergic stimulation. Administration of phenoxybenzamine blunted norepinephrine-induced pressor responses and blocked development of adrenergic hypersensitivity in the porcine myocutaneous flap model. Phenoxybenzamine significantly increased flap blood perfusion (as measured by dermofluorometry).

Animals↗
PubMed1985

Measurement of alternative blood flow in the porcine panniculus carnosus myocutaneous flap.

The dependence of a transposed myocutaneous flap on its own vascular pedicle for survival is time-related. The number of days required to establish effective sustaining perfusion from the periphery was assessed. Based on flap perfusion with associated vascular compression as monitored by the laser Doppler and dermofluorometer, adequate perfusion levels occurred at days 7 to 10 in the pig panniculus carnosus myocutaneous flap. It was established that all flaps will survive independent of the vascular pedicle when the laser Doppler readings are above 40 mV and the dermofluorometric readings are above 20%. The establishment of this baseline information now allows for the investigation of pharmacologic manipulation of the blood flow to diminish the duration of dependence on the transposed vascular pedicle.

Animals↗
PubMed1985

The levator scapulae muscle flap. A new use.

The design and use of the levator scapulae flap is reviewed. Particular attention is paid to the blood flow. A description is given of how this flap may be employed to repair smaller defects of the mouth and pharynx. It is used in association with split skin. The use of such a technique is compared to musculo-cutaneous flaps, with particular reference to the skin blood flow.

Female↗
PubMed1985

Reinnervation of skeletal muscle with a neuromuscular pedicle.

In the past decade the otolaryngologist has become interested in the problem of muscle reinnervation as it relates to laryngeal and facial paralysis. Although reinnervation by neuromuscular pedicle transfer has shown promising results in the laboratory and clinic, some investigators have had difficulty in achieving reliable results with this procedure. To further assess the technique's validity, we investigated the neuromuscular pedicle. This study utilized a strap muscle neuromuscular pedicle transfer to a contralateral strap muscle in the rabbit. The results were analyzed by the use of a number of independent measures, including electrical stimulation of the nerve, muscle contractibility, electromyography, enzyme histochemistry, reduced-silver staining for normal fibers, and the retrograde transport of the enzyme marker horseradish peroxidase. The physiologic and anatomic results demonstrated that morphologic and functional reinnervation of the experimentally isolated muscle by the transferred neuromuscular pedicle occurred. The most convincing data were produced by gross electrical stimulation, twitch and tetanic contraction, and horseradish peroxidase labeling. Electromyographic activity and other histologic findings supported the above conclusions.

Animals↗
PubMed1984

Shoulder pain and function after neck dissection with or without preservation of the spinal accessory nerve.

To compare the difference in the degree of pain and functional disability of the shoulder in patients who underwent neck dissection for the treatment of head and neck cancer, 23 patients with and 12 patients without spinal accessory nerve preservation were evaluated with a questionnaire and a physical examination. In addition, to determine what effect radiation treatment has on pain and shoulder disability, eight patients who had whole neck radiation but no neck dissection were similarly evaluated. The results of this study show that, on the average, neck dissection patients with their spinal accessory nerve preserved have less pain in their shoulders, less functional disability, and stronger results on their physical examination than did those with their spinal accessory nerve sacrificed. It was also found that the patients who received whole neck radiation treatment without neck dissection had little pain, infrequent and insignificant functional disability, and normal strength on physical examination.

Accessory Nerve↗
PubMed1984

Dynamic variations in blood flow as measured by laser Doppler velocimetry: a study in rat skin flaps.

Some of the measured variations of blood flow in skin flaps are reviewed. Ventral island skin flaps in rats are taken as an experimental model, and serial measurements using laser Doppler velocimetry have been made across the flaps for a period of up to 4 weeks postoperatively. The results demonstrate that areas of these flaps have periods of complete ischemia with no flow. These areas may survive. Conversely, apparently perfused areas later succumbed and became nonviable. The flow readings obtained are compared with fluorescence as a predictor of survival. The immediate and longer-term changes in flow across the length of these flaps are described. These findings are discussed with reference to the suggested methods of increasing the length of flap survival. The hypothesis of nonnutritive blood flow is also reassessed in the light of these findings.

Animals↗
PubMed1984

Prognostication of myocutaneous flap viability using laser Doppler velocimetry and fluorescein microfluorometry.

Formerly, flap perfusion was assessed clinically by gross evaluation of the amount of fluorescein in the developed flap prior to transfer. Recently the laser Doppler velocimeter and the perfusion microfluorometer have been developed as aids in perfusion assessment. We have used each instrument in a series of reconstructive procedures employing pectoralis or trapezius myocutaneous flaps and a series of pig groin myocutaneous flaps to assess the contribution of each to the prognostication of flap viability. While the laser Doppler does provide useful information, we have found that the microfluorometer is more selective in representing the hemodynamics of the developed flap.

Animals↗
PubMed1984

Treatment of the clinically negative neck in floor of the mouth carcinoma.

A retrospective study of 61 consecutive patients with floor of mouth carcinoma and a clinically negative neck was done to determine the value of elective treatment to the neck. Subsequent histologically proven nodal disease was analyzed according to initial treatment modality (23 surgical, 38 irradiation), stage (29--T1,27--T2,5--T3), hemi-neck at risk (midline lesions placed both hemi-necks at risk), and primary control for a minimum of 2 years (50 patients, 78 hemi-necks at risk). Neck failures were classified by T stage, extent of neck treatment (upper neck or complete) and by primary control at the time of manifest neck metastasis. Of the hemi-necks at risk with the primary controlled, 10% (17% of patients) developed nodal disease without complete neck treatment; 86% (6/7) of these patients were salvaged. The occult positive node incidence, conservatively calculated by elimination of all patients treated with elective partial or total neck irradiation, was 10% for patients with T1 and T2 lesions (7% for hemi-necks at risk). Based on the clinical course of patients with primary control, only 1 patient (2%) might have benefited from initial complete elective neck treatment. These results suggest that elective neck treatment in early (T1 and T2, N0) floor of mouth carcinoma is of doubtful value. Supraomohyoid , rather than suprahyoid dissection, is recommended if surgical treatment of the neck is undertaken.

Adult↗
PubMed1982

Studies in transtracheal ventilation catheters.

A study was undertaken to assess the applicability of transtracheal ventilation in the instance of total upper airway obstruction. The effect of transtracheal jet ventilation through a variety of inflow catheters in the dog was studied. Arterial blood gas values, intratracheal pressure and minute ventilation were compared. Deflation of the airway through an array of outflow needles was independently assessed. Hypercapnia, decreased minute ventilation, and prolonged inspiratory and expiratory durations impaired use of the smallest catheters. A dual-lumen needle, to provide exclusive respiratory access and support was then designed based on the preliminary data. Prolonged transtracheal jet ventilation with a totally obstructed upper airway was successfully conducted in a live canine subject. A review of the literature is presented.

Airway Obstruction↗
PubMed1981

Assessment of cobalt 57 tagged bleomycin as a clinical aid in staging of head and neck carcinoma.

Critical assessment of head and neck cancer with respect to staging has, on occasion, been disappointingly ineffective. We have attempted to correlate the incidence of measureable uptake of cobalt 57 tagged bleomycin by primary squamous cell carcinoma and metastatic cervical lymph nodes. Forty-six cases have been evaluated with respect to histopathological confirmation of the suspected metastatic disease. We have found that this diagnostic measure increases our acumen in staging of head and neck cancer. The relevance of the Co-Bleo scans as a diagnostic aid is reported in 46 cases. Malignant tumors greater than 2 cm in size appear to demonstrate active uptake of the imaging agent. Small tumor size and excess background radioactivity contribute to the false-negatives (17%). Inflammatory conditions or benign tumors of the salivary apparatus may result in minimal uptake, thus, a false-positive result (10%). An increase in the radioactivity of the Co-Bleo may enhance the benefits of this procedure in the search for an undiagnosed primary, as well as undiagnosed local or distant metastases.

Adult↗
PubMed1980

Management of T1 carcinoma of the anterior aspect of the tongue.

The control of carcinoma of the anterior aspect of the tongue is closely related to the extent of the primary tumor and the state of the regional lymph nodes. The most important prognostic factor is the status of cervical lymph nodes; these lymphatic beds should be considered for treatment even in patients who do not have clinically detectable nodal metastasis. Generally, patients with small localized tumors less than 2 cm in diameter (T1) are treated with surgery alone or with radiation therapy alone. In our series, local control was effective in greater than 90% of patients. Treatment failures were most common in the cervical nodes; only 40% of patients with recurrent cervical disease could be cured. The size and differentiation of the lesion, as well as the adequacy of surgical margins, appeared to be related to regional failures. Guidelines are suggested that may aid in selecting patients with T1NO lesions who require elective neck treatment with irradiation.

Carcinoma, Squamous Cell↗