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J J Wertsch

Publications and source records attributed to J J Wertsch.

16 recordsLinked to original sources
PubMed1992

AAEM case report #25: anterior interosseous nerve syndrome.

A case study is reported regarding a 57-year-old woman, chose chief complaint was weakness in her thumb that she had noted while gardening. The patient described difficulty pulling weeds out because of an inability to get a firm grip when using the thumb. Physical examination showed weakness of the flexor pollicis longus and flexor digitorum profundus to the index finger. There was no other weakness and no clinical sensory deficit. Electrodiagnostic studies revealed normal median motor and sensory nerve conduction studies with needle examination abnormalities noted only in the flexor pollicis longus, flexor digitorum profundus, and pronator quadratus. The literature on anterior interosseous nerve syndrome (AINS) is reviewed. It is important to differentiate those with idiopathic AINS as part of a neuralgic amyotrophy picture from those with an anatomic cause such as a fibrous band or anomalous muscle. Electrodiagnostic examination can be useful to help make this distinction.

Electromyography↗
PubMed1992

A portable insole plantar pressure measurement system.

To analyze plantar pressures during activities of daily living, one needs a fully portable system capable of measuring many steps over extended periods. This paper presents an inexpensive, reliable, portable plantar pressure acquisition system which we have developed. It allows the long-term recording (up to 2 hours) of pressure-time data from 14 pressure sensors within insoles. The sensor chosen is an inexpensive, conductive polymer sensor that is only 0.25 mm thick yet able to withstand sudden overloads. The portable, battery-powered, microprocessor-based data acquisition system has a memory space of 480 kbytes for data storage. It can collect pressure data from 14 insole sensors at a 20 Hz sample frequency for 5 seconds every minute over a 2-hour period. It enables the long-term measurement of plantar pressures during normal activities in a natural unrestricted environment. The design and development of this portable insole plantar pressure measurement system is described.

Foot↗
PubMed1992

Anterior tarsal tunnel syndrome.

Anterior tarsal tunnel syndrome is a rarely reported entrapment neuropathy of the deep peroneal nerve under the extensor retinaculum at the ankle. The roof of the tunnel is the inferior extensor retinaculum. The floor is the fascia overlying the talus and navicular. Within the tunnel are four tendons, an artery, a vein, and the deep peroneal nerve. Two patients with foot pain and dysesthesias had prolonged peroneal distal latencies with reduced amplitudes from the extensor digitorum brevis (EDB). Electromyographic (EMG) abnormalities were confined to the EDB. Both patients underwent surgical decompression of the anterior tarsal tunnel with reduction of their pain and dysesthesias. If present, an accessory peroneal nerve, which does not go through the tunnel, can mask EMG findings in the EDB. Diagnosing anterior tarsal tunnel syndrome can also be difficult if there is a tendency to assume that fibrillation potentials in the EDB are due to shoe wear and prolonged peroneal latencies to cool extremities.

Adult↗
PubMed1991

Ridge detection tactility deficits associated with carpal tunnel syndrome.

A ridge detection threshold task was administered to patients diagnosed as having carpal tunnel syndrome for studying performance in an occupationally relevant functional tactile inspection task. Thresholds were compared with a reference group of subjects not having carpal tunnel syndrome symptoms, performing the same task. The threshold detection task used the method of limits for studying the effects of carpal tunnel syndrome, rate of ridge height changes, ridge gradient, and direction of shearing against the skin on ridge detection thresholds for a repeated measures factorial experimental design. Sixteen carpal tunnel syndrome hands and 30 normal hands were studied. Average ridge detection threshold was 0.08 mm for the normal subjects and increased to 0.20 mm for the carpal tunnel syndrome subjects. No significant age effect was observed. These results suggest that workers having carpal tunnel syndrome may not detect an edge or surface defect in a tactile inspection task unless it was more than twice as high as detected by workers without CTS.

Adult↗
PubMed1991

A microprocessor-based data-acquisition system for measuring plantar pressures from ambulatory subjects.

We have developed a portable microprocessor-based data-acquisition system to measure discrete plantar pressures within the shoe from ambulatory subjects. The system offers improved accuracy, repeatability, portability, and flexibility not available in current commercial systems. It consists of 14 conductive polymer pressure sensors, 14 analog amplifiers, an 8-bit analog-to-digital converter, a microprocessor, 120 kbytes of memory space, and a parallel I/O interface. Seven pressure sensors are embedded within each insole and located at the posterior heel, anterior heel, the four metatarsal heads, and hallux of each foot. The system is capable of continuously sampling 14 channels of pressure data for 7 min at a 20-Hz sample rate. The recorded data are downloaded into a microcomputer for further processing, analysis, and display. Foot pressures have been acquired from a sensate subject during multiple walking trials.

Diagnosis, Computer-Assisted↗
PubMed1991

Foot pressure distribution during walking and shuffling.

The insensate foot is vulnerable to tissue damage from areas of repetitive, excessive pressures. It has been previously stated that a shuffling gait with short steps would increase the period of foot flat and thus minimize any excessive local plantar pressures. This theory was quantitatively evaluated with a portable, in-shoe pressure data-acquisition system. Seven pressure sensors were located in the left and right insoles under the metatarsal heads, hallux, and posterior and anterior heels. Plantar pressure data were acquired from ten able-bodied subjects during four minutes of continuous shuffling and walking at a metronome-controlled cadence. Peak pressures, foot-to-floor contact durations, and pressure-time integrals under each sensor during shuffling and walking were analyzed and compared. Peak pressures were decreased at all sensor sites during a shuffling gait. The greatest decreases were noted at the first and second metatarsals (up to 57.8%) and hallux (up to 63.2%). A 41.6% decrease in overall summated peak plantar pressures during shuffling was found. Foot-to-floor contact durations during shuffling were increased from 22.0% to 76.9% at all 14 sensor locations. Pressure-time integrals during shuffling were increased at the heels (up to 78.9%) and decreased at the metatarsal heads and great toes (up to 26.7%). There was a 3.3% increase in the overall summated pressure-time integral during shuffling. Our findings are consistent with the hypothesis that a shuffling gait increases the period of foot flat and the area of weight bearing, resulting in lower peak plantar pressures on any one area.

Adult↗
PubMed1990

An umbilical data-acquisition system for measuring pressures between the foot and shoe.

We have developed an umbilical data-acquisition system for measuring pressures between the foot and shoe during walking. It consists of pressure sensors in the insoles of shoes, amplifier circuits, umbilical cables, an analog-to-digital converter, and a graphics display card in an IBM PC for real-time data collection and display. The applied pressure on a sensor decreases its resistance, which causes the output voltage of the amplifier circuit to increase. We attach seven sensors to the surface of each insole of a pair of extra-depth shoes and calibrate all the sensors in the insole before and after each test using a load cell as a reference. The IBM PC samples the outputs from the sensor and the load cell and stores a piecewise linear lookup table for use in compensation for the nonlinearity of the sensor. On the PC's graphics display, two programs provide displays of foot pressures as real-time bar graphs or as analog pressure versus time curves.

Analog-Digital Conversion↗
PubMed1990

Nerve conduction studies: orthodromic vs antidromic latencies.

Variables known to affect the sensory nerve action potential (SNAP) include the method of measuring the SNAP, electrode placement and local impedance, volume conduction, temperature, age, nerve fiber composition, and duration dependent phase cancellation. There is debate, however, concerning the effect of orthodromic vs antidromic stimulation on the latency of the SNAP. This question was studied with the same methodology of those who reported a difference between antidromic and orthodromic latencies, but with control of the interelectrode distance. Twenty-five normal hands were studied. The median and ulnar digital nerves were analyzed both orthodromically and antidromically. There was careful control of interelectrode distance, which was the same for both the recording and stimulating electrodes. Studies were done with both a 3-cm and 4-cm interelectrode distance. Parameters recorded were onset latency, peak latency, terminal latency, and amplitude (baseline to negative peak, and peak to peak). Extensive statistical analysis was performed for all parameters. No differences were found between antidromic and orthodromic studies when the interelectrode distance was the same.

Action Potentials↗
PubMed1990

Reliability of sensory threshold measurement using a digital vibrogram.

Loss of vibratory sensation has been suggested as an early symptom in the diagnosis of compression neuropathies. The use of a digital vibrogram has recently been examined as a means of evaluating vibratory sensation thresholds over a range of frequencies from 8 to 500 Hz. Although this instrument does yield useful clinical information, little is known about the test-retest reliabilities of the thresholds obtained. To learn more about this, we assessed a total of 76 hands--32 normal and 44 with suspected carpal tunnel syndrome. The average sensory thresholds for onset and cessation of vibratory sensation were obtained. Pearson product-moment correlation coefficients were computed, and demonstrated improvement if an initial practice trial was administered. Our findings suggest that the vibrogram can be a reliable, clinical assessment when an initial practice trial is included as part of the standard administration.

Carpal Tunnel Syndrome↗
PubMed1989

A capacitance pressure sensor using a phase-locked loop.

We are using a Hercules (model #F4-4R, 100 psi) pressure sensor to measure the pressure between the foot and shoe. An interface circuit converts the capacitance change into voltage. Over the pressure range from 0 to 1300 kPa, the capacitance changes from 275 to 580 pF. A 555 timer circuit converts the capacitance into a frequency range from 30 to 63 kHz. A phase-locked loop (PLL) converts this frequency to voltage from 0 to 5 V, which is then filtered using a first-order, low-pass filter, having a corner frequency of 20 Hz to reduce the ripple to 10 mV. The sensor's hysteresis is about 8 percent at 40 degrees Celsius (C) and 12 percent at 20 degrees C. The sensor has a maximal nonlinearity of 8 percent and a worst-case nonrepeatibility of 7 percent. Its temperature coefficient is -0.147 percent per degree C. Its spatial sensitivity decreases nonlinearly from 1 to 0.17 from the center towards the periphery. The sensitivity of the system is 2.77 mV/kPa and the temperature drift is +0.53 percent per degree C. We monitor the pressure at 7 locations under each foot (the rear and the front heel, great toe, and 4 of the 5 metatarsal heads). A portable data-acquisition system permits continuous monitoring for 7 minutes. Test results for pressure distribution for normal walk and run are presented. Results are useful when studying normal and abnormal gait, and for possibly providing feedback (sensory substitution) to diabetic patients with insensate feet in order to help them dynamically adjust pressure distribution under their feet.

Biomechanical Phenomena↗
PubMed1989

Radial nerve palsy: a complication of walker usage.

A patient with diabetic peripheral neuropathy experienced the acute onset of a proximal radial nerve palsy after prolonged use of a walker. Nerve conduction and electromyographic studies confirmed an isolated, severe neurapraxic lesion distal to branches innervating the triceps and anconeus muscles. The acute onset and severity of this lesion suggests that it was caused by mechanical compression of the radial nerve as it exits the spiral groove. Radial mononeuropathy has been reported in conjunction with muscular effort of the triceps muscle. Previous case studies and a review of the literature are discussed. Awareness of this complication in patients using walkers and wheelchairs is important for prevention and diagnosis in rehabilitation.

Action Potentials↗
PubMed1985

Pricer palsy.

Explore the source record for details and available documents.

Female↗
PubMed1985

Pseudo-anterior interosseous nerve syndrome.

The anterior interosseous nerve syndrome (AINS) is well known. A case is presented that had electromyographic findings limited to the distribution of the anterior interosseous nerve. A small area of sensory loss and slight asymmetry of amplitudes noted on median nerve conduction studies were inconsistent with an AIN syndrome. An antecubital level partial median nerve compromise primarily involving the bundles that form the anterior interosseous nerve was surgically noted. This case illustrates that localization of a peripheral nerve lesion must include consideration of the internal topography of peripheral nerves.

Electromyography↗
PubMedDate not supplied

Electrodiagnostic medicine.

Electrodiagnostic testing examines the physiologic integrity of the peripheral nervous system. However, such testing should represent only one part of an electrodiagnostic consultation in which the entire clinical context, including the history, physical examination, laboratory studies, and electrodiagnostic testing, is considered as a whole. Although each electrodiagnostic laboratory establishes its own normal values for nerve conduction studies and needle EMG, these values should not be used in isolation. The electrodiagnostic consultation can help narrow an otherwise broad differential diagnosis, confirm a suspected diagnosis, or help define a confusing clinical picture.

Adult↗