Effects of electrical stimulation on wound healing in patients with diabetic ulcers.

OBJECTIVE: To evaluate the effects of two stimulation waveforms on healing rates in patients with diabetes and open ulcers. The hypothesis was that stimulus waveforms with minimal polar characteristics would provide significant healing for this patient sample. RESEARCH DESIGN AND METHODS: This was a prospective study that enrolled 80 patients with open ulcers. Patients received stimulation with either an asymmetric biphasic (A) or symmetric biphasic (B) square-wave pulse. Amplitudes were set to activate intact peripheral nerves in the skin. Two other groups received either very low levels of stimulation current (MC), or no electrical stimulation (C). When combined these groups were referred to as the control group. Treatment was carried out daily until the wound healed, the patient withdrew from the study, or the physician changed the overall wound management program. Average healing rates were calculated from weekly measures of the wound perimeter and were used for statistical comparison through a one-way analysis of variance. RESULTS: Stimulation with the A protocol significantly increased the healing rate, enhancing healing by nearly 60% over the control rate of healing. Stimulation with the B protocol did not increase the healing rate when compared with control subjects. CONCLUSIONS: Electrical stimulation, given daily with a short pulsed, asymmetric biphasic waveform, was effective for enhancement of healing rates for patients with diabetes and open ulcers.

Inter-hospital transport of neonatal patients on extracorporeal membrane oxygenation: mobile-ECMO.

OBJECTIVE: To describe the equipment, personnel requirements, training, management techniques, and logistic problems encountered in the design and implementation of a mobile extracorporeal membrane oxygenation (ECMO) program. DESIGN: This is a report of a technique for the transport of patients on ECMO and a description of our retrospective case series. SETTINGS: The study was conducted at a regional referral children's hospital and ECMO unit. PATIENTS: Thirteen neonatal medical patients with acute respiratory failure were transported with mobile-ECMO. RESULTS: Over a 24-month period, we transported 13 neonatal patients with mobile-ECMO. The reason for transport with mobile-ECMO was inability to convert from high-frequency ventilation (4 of 13), patient already on ECMO (1 of 13), and patient deemed too unstable for conventional transport (8 of 13). Eleven of the 13 patients were transported from other ECMO centers. Of the 13, 9 survived. No major complications during transport were reported for any of the patients. Follow-up data were available on all nine survivors of neonatal mobile-ECMO. Eight of these had normal magnetic resonance imaging scans of the brain; the ninth had a small hemorrhage in the left cerebellum. CONCLUSION: Our limited series shows that patients can be safely transported with mobile-ECMO. This program does not replace the early appropriate transfer for ECMO-eligible patients to an ECMO center.

The high signal intensity meniscus of the knee. Magnetic resonance evaluation and in vivo correlation.

This study describes the different appearances of meniscal abnormalities on magnetic resonance (MR) images and correlates macroscopic and histologic findings. Twenty-three of 40 cadaveric menisci with MR signal abnormalities were examined macroscopically; five of the 23 were studied histologically. In addition, MR studies of seven patients (14 menisci) were examined and findings were correlated arthroscopically. Histologic analysis was performed on two of these menisci. The two major findings on MR images were: (1) abnormal, high, centrally located signal intensity within the meniscus and (2) disruption of the peripheral meniscal contour. Macroscopically evident meniscal degeneration correlated well with findings on MR images in all cases. Histologic abnormalities included microcyst formation and separation of collagen bundles. Four menisci with intact outer contour lines on MR images had macroscopically identifiable tears. In addition, two meniscal tears were appreciated only after intra-articular injection of gadolinium-DTPA. We conclude that MR imaging is superior to macroscopic examination as performed by arthroscopy or arthrotomy for the detection of degenerative meniscal lesions. The technique also accurately identifies meniscal tears, a capability that might be enhanced by prior intra-articular injection of MR contrast agents.

Mobile extracorporeal membrane oxygenation.

Transport of critically ill neonates in need of extracorporeal membrane oxygenation can be risky. Their extreme cardiorespiratory instability may delay or even preclude conventional transport to an extracorporeal membrane oxygenation center. We report the use of a UH-1 helicopter specially adapted for mobile extracorporeal membrane oxygenation support to transport a critically ill neonate.

Characterization of hindlimb motoneuron membrane properties in acute and chronic spinal cats.

The purpose of this study was to determine if changes in hindlimb motoneuron membrane electrical properties occur 4-6 months after spinal transection in the adult animal. Eight acute and nine chronic animals were spinalized at T12. Intracellular recordings from motoneurons innervating the triceps surae were performed. Membrane electrical properties, including resting potential, action potential peak amplitude, afterhyperpolarization duration, rheobasic current, input resistance and axonal conduction velocity were measured. There were no statistical differences found between group means or frequency distributions in the membrane properties of motoneurons assessed from acute and chronic spinal animals. Thus, alteration of motoneuron membrane properties does not appear to be a major contributing factor to the hyperexcitable hindlimb reflex activity demonstrated by chronic spinal animals.

Characterization of postsynaptic potentials evoked by sural nerve stimulation in hindlimb motoneurons from acute and chronic spinal cats.

The purpose of this study was to characterize the changes in postsynaptic potentials recorded in ankle extensor motoneurons resulting from activation of the sural nerve after spinal cord transection in the adult cat. Eight acute and nine chronic animals were spinalized at T12. Intracellular recordings from motoneurons innervating the triceps surae were performed. Sural nerve stimulation evoked complex synaptic potentials consisting of early and late components in all motoneurons. Early excitatory and inhibitory postsynaptic potentials (PSPs), as well as long latency excitatory postsynaptic potentials were recorded and averaged for assessment of PSP amplitude and duration. Early PSPs, both excitatory and inhibitory, were significantly larger in the motoneurons of cats spinalized 4-6 months earlier. Central latency of excitatory potentials were similar in the two samples of motoneurons, but the central latency associated with the initial inhibitory PSP was significantly shorter in the recordings from motoneurons of chronic spinal cats. In most recordings, an additional inhibitory PSP followed the initial excitatory PSP in motoneurons, and this secondary inhibitory PSP was similar in peak amplitude and duration in both samples of motoneurons. Also, a long latency excitatory PSP was recorded in a large percentage of motoneurons from both samples. This potential was typically of greater amplitude and longer duration in the motoneurons from chronic animals, when compared to recordings from acute animals. Although changes in amplitude and duration of PSP activity could be documented, there was no marked alteration in the frequency of occurrence of each PSP pattern recorded from the two preparations. This suggests that the synaptic pathways mediating the sural nerve reflexes have not qualitatively changed in the chronic spinal animal. The changes in amplitudes and durations of the PSPs in the chronic spinal cat indicate, however, that quantitative changes have occurred. The quantitative changes have probably occurred in the interneuronal networks activated by cutaneous nerve (sural) stimulation, since it was shown that only minor changes in motoneuron membrane properties could be recorded in these same chronic spinal animals.

Characterization of synaptic potentials in hindlimb extensor motoneurons during L-DOPA-induced fictive locomotion in acute and chronic spinal cats.

Intracellular recordings were carried out in extensor hindlimb motoneurons during L-DOPA-induced fictive locomotion from acute and chronically spinalized cats. It was demonstrated that motoneurons in chronic animals exhibited irregularly occurring, high frequency discharges within a given burst of a spike train, and sporadic membrane potential depolarizations and hyperpolarizations correlated with extensor and flexor nerve filament activity, respectively, during the locomotor cycle. In contrast, motoneurons recorded from acute cats demonstrated smooth membrane potential fluctuation and regularly occurring low frequency spike discharges. These results indicate that the pharmacologically activated central pattern generator (CPG) for locomotion in young adult chronic cats spinalized at two weeks of age produces disorganized locomotor-like patterns in the absence of sensory feedback. It is suggested that the above-mentioned characteristics of membrane potential fluctuations and spike discharges are not due to alterations in the motoneuron membrane properties, but instead are due to changes in the inputs to the motoneurons.

The large temporal horn: MR analysis in developmental brain anomalies versus hydrocephalus.

PURPOSE: To utilize MR to delineate the morphologic abnormalities of the temporal horn and adjacent structures in patients with congenital brain anomalies and to differentiate these findings from the temporal horn alterations in obstructive hydrocephalus. PATIENTS AND METHODS: Thirty-six patients were included in this retrospective study, including eight with agenesis of the corpus callosum (ACC), four with lissencephaly (lis), four with lobar holoprosencephaly (holo), as well as 20 with isolated obstructive hydrocephalus due to tumor (17 patients) or aqueductal stenosis (three patients). Twenty patients with normal scans were included as controls. RESULTS: Coronal plane image analysis showed that 75% of patients with brain anomalies had enlargement of the temporal horns, most prominently involving the inferolateral aspects of the ventricle (8/8 ACC, 4/4 lis, 0/4 holo). Hippocampal formations were small in 62% (6/8 ACC, 3/4 lis, 1/4 holo). An abnormal, vertical orientation (incomplete inversion) of the hippocampal formations was observed in 82% (8/8 ACC, 4/4 lis, 1/4 holo). Focal thinning of the white matter lateral to the temporal horn was seen in 50% (8/8 ACC, 0/4 lis, 0/4 holo). All patients with isolated obstructive hydrocephalus showed enlargement of the temporal horns, most pronounced in the superior-lateral region. Hippocampal formations showed normal, horizontal orientation (complete inversion) and were of normal size in 17 of 20 patients; the only exceptions included patients with severe hydrocephalus where the hippocampi were flattened along the inferior margin of the temporal horn. Temporal lobe white matter was normal in the 17 patients with mild or moderate hydrocephalus: diffuse white matter thinning inferolaterally was observed in the three patients with severe hydrocephalus. Distinct differences were present in the morphology of the temporal horn and surrounding brain in congenital brain disorders compared with those in patients with hydrocephalic. The anomalous brains showed enlargement as a result of incomplete development, and the hydrocephalic brains showed enlargement as a result of increased intraventricular pressure. CONCLUSION: Temporal horn enlargement in lissencephaly and agenesis of the corpus callosum should not be misinterpreted as hydrocephalus. Analysis of temporal lobe morphology will allow differentiation if doubt exists.

Hemangiomas and vascular malformations of the head and neck: MR characterization.

PURPOSE: To characterize the MR appearance of the common hemangioma of infancy as well as low- and high-flow vascular malformations of the head and neck. PATIENTS AND METHODS: Twenty patients with vascular lesions of the head and neck proved either by pathology, angiography, and/or unequivocal clinical diagnosis were included. Vascular lesions included 15 low-flow lesions (four hemangiomas, 10 venous malformations, one lymphatic malformation), and five high-flow lesions (three arteriovenous malformations (AVMs) and two invasive combined malformations). All patients had MR studies (generally 1.5 T using routine T1- and T2-weighted spin-echo sequences). Nine had postgadolinium, gradient recalled-echo, CT, and/or angiographic studies. FINDINGS: Deep hemangiomas and venous malformations demonstrate intermediate signal in T1-weighted images, heterogeneous high signal on T2-weighted images, and prominent enhancement. Involuting hemangiomas show focal areas of high signal intensity on T1-weighted images due to fatty replacement. Venous malformations may demonstrate venous lakes seen as homogeneous regions of high signal intensity on T2-weighted images and phleboliths seen as low signal foci. The one patient with lymphatic malformation showed a large multicystic submandibular mass with large hemorrhage-fluid levels. Features of high-flow lesions (AVMs) include serpiginous signal voids, absence of a dominant mass, and intraosseous extension with decreased marrow signal on T1-weighted images. Invasive combined vascular malformations showed serpiginous flow voids and infiltrative solid masses. Low-flow lesions (hemangiomas, venous, and lymphatic malformations) demonstrate distinct MR findings allowing their differentiation from high-flow lesions (AVMs). Deep hemangiomas and venous malformations appear as solid masses and may look identical. Venous lakes and phleboliths are features of venous malformations which, when present, may help in diagnosis. Combined vascular malformations share features of both low- and high-flow malformations. CONCLUSION: MR is useful in delineating the extent of disease and differentiating low- and high-flow vascular lesions.

Recruitment data for nerve cuff electrodes: implications for design of implantable stimulators.

Recruitment characteristics of nerve cuff electrodes implanted in four cats for five months were measured. Monopolar, bipolar, and tripolar configurations were considered. Approximately twice the current was required to achieve a given response using the tripolar configuration as compared with monopolar stimulation. Bipolar stimulation also required more current than monopolar stimulation. Using the recruitment data, a number of strategies for modulating muscle tension were considered. It was shown that both pulse amplitude and pulse duration should be software-selectable to achieve adequate control of muscle tension when using either pulse amplitude modulation or pulse duration modulation. When using pulse amplitude modulation, it was found to be desirable to operate at a low pulse duration in the high end of the allowable range for pulse amplitude. For pulse duration modulation, one should operate at a low pulse amplitude in the high end of the allowable range for pulse duration. The effect of pulse amplitude and pulse duration step size on the maximum step change in muscle tension and the linearity of the recruitment curves were examined. The use of logarithmic steps in the modulation parameter was examined and was shown to result in improved controllability and linearity.

Neuromuscular electrical stimulation of the muscles surrounding the shoulder.

Neuromuscular electrical stimulation (NMES) can be used to augment range-of-motion, strengthening, and facilitation treatment programs of the muscles surrounding the shoulder. The purposes of this article are 1) to describe the uses of NMES around the shoulder joint as developed through our clinical use and 2) to detail the effects of an NMES program on chronic shoulder subluxation as determined by a clinical study. Because of the complexities of this multiarticular joint, NMES is most useful in the initial phase of the ROM, and stimulated contractions are compromised, relatively, as the humerus moves above the 90-degree horizontal plane. The use of NMES to provide scapular stabilization often entails unwanted alteration of the pressures on the spinal column, occasionally making the treatment program unusable. Electrical stimulation to prevent or correct shoulder subluxation, especially in the neurologically involved patient, provides the therapist with a powerful new treatment technique. In a group of stroke patients, shoulder subluxation was reduced significantly (p less than .05) at the completion of a six-week NMES program. Some of the problems, and possible solutions, unique to the development of electrical stimulation programs for the shoulder muscles are discussed.

Neuromuscular electrical stimulation for the head-injured patient.

Recent research has shown that electrical stimulation is effective in treatment programs designed to maintain or gain range of motion, to facilitate voluntary motor control, and to strengthen muscles weakened by disuse. All of these treatment goals are relevant to the head-injured patient who frequently demonstrates profound disuse atrophy, joint contractures with excessive muscle tone, and decreased voluntary motor capabilities. As the cognitive status of the head-injured patient improves, electrical stimulation can be incorporated into traditional treatment programs to enhance their effectiveness. This article discusses using neuromuscular electrical stimulation with programs aimed at managing contractures, reducing spasticity, and facilitating voluntary motion. The limitations of electrical stimulation in the head-injured patient population are addressed.

Electrical stimulation of wrist and fingers for hemiplegic patients.

Passive cyclical electrical stimulation was applied during a four-week treatment program to the wrist and finger extensors of 16 hemiplegic patients with flexor spasticity. The study noted the effects of this treatment on the patients' sensation; spasticity; passive range of motion of the wrist, metacarpophalangeal, and proximal interphalangeal joints; and strength in the wrist extensor muscles. Patients were divided into chronic and subacute groups. Both groups received electrical stimulation for three half-hour periods a day, seven days a week, as a substitute for all other range-of-motion techniques. Flexion contractures were prevented in the subacute group of patients at the wrist, metacarpophalangeal, and proximal interphalangeal joints. A statistically and clinically significant increase in wrist extension range occurred in the chronic group that had wrist flexion contractures before the electrical stimulation. Increased extension was noted at the metacarpophalangeal and proximal interphalangeal joints of patients in the chronic group. Those patients with some voluntary wrist extension before the treatment began were able to increase their extension strength during stimulation. No changes in skin sensation were noted and only a general trend in decreasing spasticity was apparent.

Atlanto-axial subluxation and cervical osteomyelitis: two unusual complications of adenoidectomy.

Grisel's syndrome (atlanto-axial subluxation) and cervical osteomyelitis are two unusual complications of adenoidectomy. We present two patients; one with atlanto-axial subluxation following uncomplicated tonsillectomy and adenoidectomy, and one with cervical osteomyelitis following uncomplicated adenoidectomy. Both patients presented with persistent postoperative neck pain. Surgical intervention, as well as long-term intravenous antibiotics, was required. A high index of suspicion, as well as cervical spinal series with flexion-extension views, is necessary for diagnosis. Flexible nasopharyngoscopy and computed tomography of the cervical spine also aided in diagnosis and treatment planning. With early diagnosis and proper treatment, the prognosis is good. Neurologic sequelae were prevented in both of our patients.

Trouble shooting the extracorporeal membrane oxygenator circuit and patient.

Patients requiring extracorporeal membrane oxygenation (ECMO) often become totally dependent on the mechanical life support. The Extracorporeal Life Support Organization (ELSO) reports 2486 incidents of mechanical complications in 5905 ECMO supports. To help decrease the number of mechanical complications, an active quality assurance program was initiated at our institution. This resulted in identification of only 14 incidents of mechanical complications in 100 patients (neonate, pediatric, adult, and cardiac). Techniques for dealing with problems such as loss of roller pump occlusion, changing out of the membrane lung or heat exchanger without interrupting ECMO support, venous air lock, tamponade, emergency transfusion, and other situations were generated into written policies and procedures. We routinely review and practice problem solving techniques with specific emphasis on monitoring patient hemodynamics and appearance. We conclude that written policies and procedures, "water drills," and continuing education can be beneficial in early recognition, intervention, and/or prevention of ECMO mechanical complications.

Functional test for the hemiparetic upper extremity.

A test, called the Functional Test, that evaluates the integrated function of the total upper extremity of an adult hemiparetic patient has been developed. It was used with 82 patients admitted to Rancho Los Amigos Hospital for stroke rehabilitation, together with a battery of six objective test measures. Sequential testing by two examiners demonstrated that the test had interrater reliability. The Functional Test score accounted for 87 percent of the variation in the scores achieved by the patients on the six separate objective measures. This tool integrates the information from these objective assessments and appears to be a valid measure of functional use of the hemiparetic upper extremity. The test can be administered in approximately 30 minutes, can be used in different treatment settings, and provides an accurate and immediate assessment of upper extremity capabilities.

Cerebrovascular disease.

The recent literature addresses the early detection of cerebrovascular disease using imaging techniques, metabolic assessment using spectroscopy, developments in quantitative analysis of brain blood flow, and new interventional techniques for aneurysm obliteration and carotid angioplasty.

Effects of joint angle, electrodes and waveform on electrical stimulation of the quadriceps and hamstrings.

Isometric twitch moments of the quadriceps and hamstrings were recorded in 20 normal subjects at 40 cells of a superimposed grid. Results were compared at 15, 45, and 75 degrees of knee flexion. Bipolar stimulation at 6 pairs of cells was performed to determine the effect of electrode size, waveform, and polarity on moments. The quadriceps had one region of excitability over the femoral nerve and a second broader region of excitability over the muscle mass. Neither location was significantly affected by knee flexion. Regions of excitability for the hamstrings demonstrated more individual variation and were affected by knee angle. Electrode size had little effect on moments produced with monopolar or bipolar stimulation. When monophasic waveforms were used, reversing polarity generally caused changes in moments of greater than 20%, whereas polarity had no significant effect when using biphasic waveforms. Moments produced with biphasic waveforms were always greater (by 20-25%) when compared with monophasic waveforms. During monopolar, monophasic stimulation, the anode, often termed the "indifferent" electrode, produced nearly 70% of the moment produced by the cathode.

Effects of waveform parameters on comfort during transcutaneous neuromuscular electrical stimulation.

Twenty-three females between the ages of 19 and 35 were studied in order to compare the effects of variations in pulse duration, waveform symmetry, and source regulation on comfort during quadriceps surface stimulation at amplitudes necessary to produce 27 Nm torque. Stimulation parameters compared were: 1) 50 and 300 microseconds pulse durations, 2) asymmetrical and symmetrical biphasic waveforms, and 3) current and voltage source regulation. Subjects overwhelmingly preferred the 300 microseconds pulse duration regardless of waveform or source regulation, strongly preferred the symmetrical biphasic waveform, and had inconsistent preference for either regulated voltage or regulated current sources.