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Biomedical subjects

S M Tuel

Publications and source records attributed to S M Tuel.

At least 19 recordsLinked to original sources
PubMed1998

Effect of nerve block on sural amplitude during remote muscle contraction.

We previously reported that the median sensory nerve action potentials (SNAPs) increased in amplitude during both near (3) and remote (4) muscle contraction. The objective of the present project was to begin to study the pathway by which this occurred. The sural amplitude was measured after one min. of isometric biceps contraction and compared pre and post lidocaine nerve block in 10 healthy subjects. The baseline was defined as the least amount of current needed to elicit a minimal sural response pre contraction. This level of stimulus remained constant throughout the experiment. Results showed that the sural amplitude peaked 4 min. after muscle contraction. An 8.1 microV increase in sural amplitude from baseline was noted pre injection as 5 min. post contraction, and an increase of 13.4 microV was noted comparing pre to post injection amplitudes at the same time. Statistical analysis using two-way interaction comparing the time courses pre and post injection showed a 92% chance the responses were dissimilar Post hoc least significant difference (LSD) analyses were significant at 4 min. (p = .005) and 6 min. (p = 0.29) post contraction. In conclusion, the increase in sural amplitude after remote muscle contraction was no longer apparent after proximal sural nerve block. This suggests that the nerve itself is required in the final common pathway for the transmission of this induced signal.

Action Potentials↗
PubMed1995

Focal depression of cortical excitability induced by fatiguing muscle contraction: a transcranial magnetic stimulation study.

Motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS) and transcranial electrical stimulation (TES) of the motor cortex were recorded in separate sessions to assess changes in motor cortex excitability after a fatiguing isometric maximal voluntary contraction (MVC) of the right ankle dorsal flexor muscles. Five healthy male subjects, aged 37.4 +/- 4.2 years (mean +/- SE), were seated in a chair equipped with a load cell to measure dorsiflexion force. TMS or TES was delivered over the scalp vertex before and after a fatiguing MVC, which was maintained until force decreased by 50%. MEPs were recorded by surface electrodes placed over quadriceps, hamstrings, tibialis anterior (TA), and soleus muscles bilaterally. M-waves were elicited from the exercised TA by supramaximal electrical stimulation of the peroneal nerve. H-reflex and MVC recovery after fatiguing, sustained MVC were also studied independently in additional sessions. TMS-induced MEPs were significantly reduced for 20 min following MVC, but only in the exercised TA muscle. Comparing TMS and TES mean MEP amplitudes, we found that, over the first 5 min following the fatiguing MVC, they were decreased by about 55% for each. M-wave responses were unchanged. H-reflex amplitude and MVC force recovered within the 1st min following the fatiguing MVC. When neuromuscular fatigue was induced by tetanic motor point stimulation of the TA, TMS-induced MEP amplitudes remained unchanged. These findings suggest that the observed decrease in MEP amplitude represents a focal reduction of cortical excitability following a fatiguing motor task and may be caused by intracortical and/or subcortical inhibitory mechanisms.

Adult↗
PubMed1994

Electrophysiologic analysis of snap amplitude in orthodromic and antidromic studies.

In 1966, Buchthal and Rosenfalk established that the sensory nerve action potential (SNAP) amplitude increased with increasing number of nerve fibers. Lambert and Dyck's in vitro study of the sural nerve, however, found the SNAP amplitude of a single fascicle was equivalent to the SNAP amplitude of the entire nerve. The current study confirmed Buchthal and Rosenfalk's original findings, and discovered an in vivo equivalent to Lambert and Dyck's findings. Ten subjects were used as their own controls. Orthodromic stimulation of both the index and middle fingers stimulated individually versus simultaneously revealed a significant increase in amplitude (p < 0.001). When the recording and stimulating electrodes were reversed, without physically changing the electrodes on the subject, there was no significant difference between the antidromic SNAP amplitudes recorded from separate fingers, or from both fingers simultaneously. Although in both cases the number of recorded nerve fibers approximately doubled, the effect on the SNAP amplitude was very different. This seemingly paradoxical result can be explained by electrophysiologic differences in the recording methods, without using the concept of fiber density.

Action Potentials↗
PubMed1993

Successful treatment of immobilization hypercalcemia using calcitonin and etidronate.

Hypercalcemia of immobilization may present in patients with spinal cord injury, multiple fractures, or Landry-Guillain-Barre Syndrome. It is attributed to an increase in bone resorption and diminished bone formation characterized clinically by elevated serum calcium levels, hypercalciuria, increased risk of urinary lithiasis, and renal failure. Traditional treatment methods can interfere with the intensive level of therapy provided in the comprehensive rehabilitation program. Other treatments, less disruptive of the rehabilitation milieu, are possible. Reported are six patients with hypercalcemia of immobilization who were successfully treated with combination therapy of salmon calcitonin and sodium etidronate. The patients developed hypercalcemia an average of 69 days after the onset of illness. Serum calcium levels dropped an average of 2.8mg/dL (12.3mg/dL, SD 1.33 to 9.5mg/dL, SD 0.42) within eight days after initiation of treatment. In two patients, 24 hour urine excretions of calcium decreased by 414 and 210mg/day, respectively. All patients had a reduction in serum calcium levels noted within two days of treatment, and a normal serum calcium levels within one week. Patients were usually changed to a single medication maintenance regimen, sodium etidronate, within a few days. Full therapies in the treatment gyms were given to all patients within a day of initiation of the combined treatment. These two drugs appear to have a rapid and combined effect on the treatment of hypercalcemia of immobilization, and allow full participation in a comprehensive rehabilitation program.

Adolescent↗
PubMed1992

Pregnancy, labor and delivery post spinal cord injury.

There are approximately 3,000 women of childbearing age who become spinal cord injured each year in the United States. There are few reports in the literature that address pregnancy, labor and delivery in this patient population. We are reporting on 22 women post spinal cord injury who had 33 pregnancies. There were equal numbers of paraplegic and quadriplegic women. Three pregnancies aborted, one spontaneously. The babies were near normal or normal weight with one exception. The mothers waited 5 years on average to become pregnant. Cesarean section was performed on 43% of pregnancies. Abnormal presentations occurred in over 10% of pregnancies. Indications for cesarean section included 5 that were repeats; the remainder were necessary due to bleeding (1), breech presentation (1), transverse presentation (2), lack of progress (2), onset of labor 1 day post spinal fusion, and a mother's request to have tubal ligation. Epidural anesthesia was selected for 9 deliveries; 6 of these patients had controlled autonomic hyperreflexia. Five general and 4 local anesthetics were used, and 12 patients received no anesthesia. Diagnostic ultrasound and amniocentesis were used selectively. Complications included autonomic hyperreflexia (9), frequent urinary tract infections, infected pressure sores (3, 2 resulting in below-knee amputations), seizures during and after delivery, pneumonia, bladder stones (2), episiotomy dehiscence (1), and breakdown of spinal fusion. The newborns were healthy, although one double footing breech vaginal delivery had an APGAR of 1 at 1 min, 7 at 5 min and 9 at 10 min. One premature baby, who weighed only 1600 g, was a precipitate birth at home unattended. Implications for the care of pregnant SCI women are discussed.

Abortion, Induced↗
PubMed1992

Heterotopic ossification of the extensor tendons in the hand associated with traumatic spinal cord injury.

Heterotopic ossification (HO) occurs in spinal cord injury (SCI), most frequently in the large joints such as hips, shoulders, knees, and elbows. It always occurs below the level of neurologic lesion. In the upper extremities, HO associated with SCI usually involves the flexor side of the involved joint. HO has only been reported once to involve the hands and rarely develops parallel to the long bones. We present a 44-year-old male with C5 traumatic SCI who developed HO involving the extensor tendons of one hand. The HO was discovered four months after the SCI and involved the extensor sheaths of the second, third, and fourth digits, from the metacarpal-phalangeal joint to the proximal inter-phalangeal joint. The patient had been improving neurologically with poor to fair extension of the right wrist allowing for tenodesis finger flexion, but with the onset of HO he lost some functional grasp. Diagnosis, possible etiology, and treatment (including options of radiation therapy and surgery) are discussed.

Adult↗
PubMed1992

Continuous intrathecal baclofen in spinal cord spasticity. A prospective study.

Continuous intrathecal infusion of the well known antispastic medication baclofen was evaluated in ten consecutive patients. One year after pump implantation the average Ashworth scale for muscle tone decreased, compared with before treatment, 2.32 points (P < 0.0001), reflexes decreased 2.22 points (P < 0.0001) and the spasm score decreased 1.65 points (P < 0.0001). The average dose increased from 92.22 to 290.95 micrograms (P < 0.0001) between the 1st month of treatment and 1 yr of treatment. The dosage for all patients more than doubled (P < 0.0022) between 3 months and 1 yr postimplantation. There was no significant difference for muscle tone, reflexes or spasms at 3 months v 1 yr. Complications were not unusual and included temporary atelectasis, orthostatic hypotension with escalation of baclofen dose, loss of penile erections, postsurgical pseudo-meningoceles, catheter disruptions and exhausted pump reservoirs. One patient suffered a seizure apparently related to a rapid withdrawal from intrathecal baclofen as a result of catheter sequestration. All patients required a period of intensive inpatient rehabilitation to benefit functionally from the decreased motor tone and/or increased voluntary motor control. The procedure is expensive and close follow-up is necessary for assessing efficacy and refilling the pump. Intrathecal baclofen infusion by subcutaneous pump is useful in treating the effects of spinal spasticity resistant to oral medications. However, there appears to be accommodation to intrathecal baclofen necessitating escalating doses to maintain clinical effects.

Adult↗
PubMed1992

Intrathecal baclofen in hereditary spastic paraparesis.

Intrathecal baclofen has not been previously evaluated for the treatment of the disabling hypertonia associated with hereditary spastic paraparesis. Muscle tone and deep-tendon reflexes were evaluated in three patients with hereditary spastic paraparesis after a double-blind, cross-over bolus injection of intrathecal baclofen. Patients underwent placement of a subcutaneous pump for continuous infusion of intrathecal baclofen. Three months after implantation the muscle tone decreased 2.04 points (p less than .0001) and the reflex score decreased 2.25 points (p less than .001). Patients initially reported subjective weakness, but muscle testing revealed either an increase or no change in voluntary motor function. Baclofen doses of 60 to 264 micrograms per day were required for effective control of muscle tone and spasticity. Much of the disability in familial spastic paraparesis may be related to the loss of suprasegmental inhibition of spinal reflexes overwhelming the residual voluntary motor function.

Baclofen↗
PubMed1992

Prosthetic management of hemicorporectomy patients: new approaches.

Functional outcome with hemicorporectomy prosthetic management has improved little in the last 20 years. Patient expectations for independence, comfort, and cosmesis have been disappointed with traditional bucket designs. This report describes the prosthetic management of a paraplegic patient who underwent hemicorporectomy at T12 secondary to complications from a lumbar ependymoma. Four successive prostheses were developed using foam and resin combinations, computer-assisted pressure monitoring, and interdisciplinary team feedback regarding design and fabrication. A total-contact bucket with removable liner was created, allowing management of the ileal diversion and colostomy. Prosthetic legs were attached to improve wheelchair balance and cosmesis. In his final prosthesis, the patient's function and appearance was equivalent to a well-rehabilitated midthoracic spinal cord trauma patient. Sitting tolerance exceeded 12 hours a day. Each prototype is discussed, including design, materials, fabrication process, patient acceptance and functional independence, and complications.

Adult↗
PubMed1992

Interdisciplinary management of hemicorporectomy after spinal cord injury.

Hemicorporectomy (HCP) is infrequently used, but its effects can devastate the patient's body image, autonomic function, and physical abilities even more than a spinal cord injury of comparable level. Interdisciplinary management is of the utmost importance. This report describes the 2 year course, including four separate rehabilitation admissions, of a patient who was initially paraplegic, and then underwent a HCP for complications secondary to a cauda equina ependymoma. The patient's expectations for functional independence were established by his successful initial spinal cord rehabilitation. The HCP was performed 6 months after initial discharge secondary to infected Harrington rods and rapid spread of the tumor. Extensive use of the interdisciplinary team approach allowed comprehensive analysis and treatment of the patient's comfort, mobility, skin tolerance, and upper extremity functional abilities. Four successive prostheses were developed and modified, until all concerns were successfully addressed. The patient ultimately became completely independent at the wheelchair level. The evaluations, treatment plan, and emphasis of each discipline, including physical therapy, occupational therapy, rehabilitation nursing, therapeutic recreation, social work, vocational rehabilitation, and physiatry are summarized. Differences between the patient's course and standard spinal cord rehabilitation are detailed.

Adult↗
PubMed1991

Spinal cord seizures: a possible cause of isolated myoclonic activity in traumatic spinal cord injury: case report.

Spinal cord seizures are infrequently reported. They have been associated with intravenous dye placement, transverse myelitis and multiple sclerosis, but never with traumatic spinal cord injury (SCI). We report the case of a 48-year-old SCI male with complete C6 quadriplegia, and apparent spinal cord seizures. These seizures were characterised by myoclonus simplex activity involving the upper extremities only. The lower extremities were spared. The patient was conscious throughout the myoclonic activity and an electroencephalogram of the brain obtained during an event revealed no cortical epiliptiform activity. The seizures lasted approximately 30 seconds to a few minutes, and an acute increase in blood pressure and a decrease in pulse generally occurred 30 to 60 seconds prior to the event. Previously reported spinal cord seizures in multiple sclerosis were frequently treated with carbamazepine. In this case successful treatment was with diazepam. Spinal cord seizures may present in those with traumatic SCI. Benzodiazepines may be useful in the treatment of spinal cord seizures.

Blood Pressure↗
PubMed1991

Rehabilitation of quadriparesis secondary to spinal cord sarcoidosis.

Sarcoidosis is a multisystem granulomatous disorder that rarely involves the spinal cord. This report describes the presentation and rehabilitative course of a 31-yr-old man with quadriparesis secondary to spinal cord sarcoidosis. The patient had insidious, progressive weakness in his arms and legs for six weeks before evaluation. Examination revealed a C4 incomplete spinal cord injury. Computed tomography demonstrated an intrinsic cord lesion from the brainstem to approximately T8. Magnetic resonance imaging (MRI) suggested the lesion was granulomatous and cervical laminectomy confirmed noncaseating granulomas. The patient was started on high dose steroids, subsequently gained strength in the distal upper extremities, and was sent for spinal cord rehabilitation. Examination revealed 3 to 4+/5 strength in the upper extremities, 2- to 3-/5 in the lower extremities. The right side was slightly stronger than the left, with proximal musculature stronger than distal. Sensory examination was intact except in the C-8 to T-2 dermatomes. The patient was dependent in self-care and mobility except for feeding. Initial progress was inhibited by severe spasticity requiring medication, but by discharge he was independent at the wheelchair level with 4/5 strength in all four extremities except for his hands, which had 3/5 strength. Sensory exam did not change. Follow-up MRI studies revealed reduction of the lesion. Review of previous cases revealed that myelopathy is the most common presenting complaint and cervical segments are most commonly involved. Survival averaged almost three years and significant gains were made in functional status. Rehabilitative course and special considerations, treatment and follow-up recommendations are discussed.

Activities of Daily Living↗
PubMed1991

Inpatient comprehensive rehabilitation after liver transplantation.

Liver transplantation has become a standard treatment for liver failure and is covered by Medicare. Transplantation has up to an 80% survival rate; however, the postoperative course can include many complications, a long hospital admission and the need for the involvement of many medical and therapeutic disciplines. Ideally, this is provided by a coordinated comprehensive rehabilitation program, but descriptions of this type of management are absent from the literature. This report describes the case of a 54-yr-old male with alcoholic cirrhosis who underwent orthotopic liver transplantation. His postoperative course was complicated, and he developed global weakness secondary to hepatic neuropathy with superimposed type II steroid-induced myopathy. Four months after the transplant he was unable to sit up in bed and was admitted to the rehabilitation unit. The patient required two subsequent admissions to the acute hospital for complications; however, close cooperation between the surgical transplant team and the rehabilitation team facilitated functional improvement and enabled discharge to home in less than 8 wk. At discharge, the patient was independent in bed mobility, transfers and self-care, and he was ambulating with contact guard. Medical issues, including evaluation, medications and possible complications in the rehabilitative phase are discussed.

Hospitalization↗
PubMed1991

Pregnancy following spinal cord injury.

Each year about 2,000 women of childbearing age in the United States have a spinal cord injury. Only a few mostly anecdotal reports describe pregnancy after such an injury. In a retrospective study of 16 women with a spinal cord injury, half of whom have a complete injury and about half quadriplegia, 25 pregnancies occurred, with 21 carried to full term. The women delayed pregnancy an average of 6.5 years after their injury, with an average age at first pregnancy of 26.8 years. Cesarean section was necessary in 4 patients because of inadequate progress of labor. In 5 deliveries an episiotomy and local anesthesia were required, 7 required epidural anesthesia, including all cesarean sections, and 10 did not require anesthesia. Several complications have been identified in the antepartum, intrapartum, and postpartum periods including autonomic hyperreflexia, premature labor, pressure sores, urinary tract infections, abnormal presentation, and failure to progress. Ultrasonography and amniocentesis were used selectively. Women with spinal cord injuries can have healthy children, although there are significant risks and these women have special needs.

Adult↗
PubMed1990

Cost-effective screening by nursing staff for urinary tract infection in the spinal cord injured patient.

Screening tests for urinary tract infections (UTI) are used in the clinical laboratory setting. This study evaluated the efficacy of screening by nursing staff on the inpatient unit, instead of the clinical laboratory, in the spinal cord-injured population. Fifty-three consecutive traumatically spinal cord-injured patients had weekly urine collection, except when infected or on antibiotics. Each urine sample was tested by a nitrite and leukocyte esterase (LE) dipstick (Chemstrip LN by Bio-Dynamics) and by routine clinical laboratory culture. A total of 169 tests were completed. The correlation coefficients of the LE and the nitrite tests with the culture were 0.604 (P less than 0.001) and 0.663 (P less than 0.001), respectively. The correlation of the combined tests was 0.837 (P less than 0.001). The sensitivity, specificity and positive and negative predictive values of nitrite-LE testing by nursing staff were calculated and compared favorably with published performances of clinical laboratory staff. When measured against the culture, the combined nitrite and LE test had a sensitivity of 79%, specificity of 99% and positive and negative predictive values of 96% and 95%, respectively. The use of a protocol where laboratory culture is performed only when the dipstick test is positive, would reduce the number of cultures by 83%. After extra costs of the additional screen are added, the use of dipstick screening methods by nursing staff can reduce the cost of weekly urine screening by 73%, with a false negative rate of only 4.4%. The expense and complexity of screening for UTI is reduced, response time is minimized and laboratory cultures will have a higher probability of useful clinical information.

Adolescent↗
PubMed1986

A method for stabilizing chronic gastrostomy or jejunostomy tubes.

Haphazard and inefficient securing of chronic gastrostomy or jejunostomy tubes causes major complications due to migration of the percutaneous feeding tube, including pyloric or intestinal obstruction, obstructive jaundice, and impaired feeding. These problems associated with current anchoring techniques can be prevented by following an inexpensive, easily learned stabilization method using sterile gauze pads and tape that fixes the tube in position.

Bandages↗