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In this article the principles and practice of clinical EMG are described. The basic components of EMG instrumentation include specialized intramuscular recording electrodes, a preamplifier, amplifier, and displays. Displays are usually both visual and auditory, using the CRO and a loudspeaker, respectively. The motor unit is the functional unit of muscles and is the anatomic basis for clinical EMG. There are distinct sites along the motor unit pathway where pathologic changes may produce EMG abnormalities. These sites include (1) anterior horn cell; (2) spinal nerve root; (3) plexus; (4) peripheral nerve; (5) myoneural junction; and (6) muscle fiber. Normal EMG potentials in resting muscle (which is predominantly silent) include end-plate potentials and miniature end-plate potentials, which are present only in the region of the motor end plate. Individual motor unit potentials can be observed when a muscle contracts minimally. The morphology of motor unit potentials varies within a normal range, which is somewhat specific for each muscle, depending on its nerve-muscle fiber innervation ratio. Stronger contraction of a muscle produces an orderly recruitment of motor units, referred to as an interference pattern. In resting muscle the most commonly encountered abnormal potentials include (1) positive sharp waves, (2) fibrillation potentials, (3) fasciculation potentials, and (4) high frequency discharges. Abnormalities in motor unit morphology can be detected best in minimally contracting muscles. Polyphasic motor units contain more than four phases and constitute less than 15 per cent of all motor units in a given muscle. In myopathy the motor unit potentials are often polyphasic. They are of low amplitude and short duration. In neuropathy motor unit potentials may also be polyphasic; however, the size of the motor unit is either normal or of increased amplitude and duration depending on chronicity. Such findings in myopathy and neuropathy correlate with known pathoanatomic changes in these conditions. In myopathy the motor unit interference pattern will often be normal or enhanced despite clinical weakness in the muscle. In neuropathy the interference pattern will be reduced, and when neuropathy is severe a single large motor unit may produce a single motor unit pattern. Besides its application as a valuable aid in diagnosis of neuromuscular disorders, electromyography is also utilized for prognosis, determining the need for surgery, planning programs of rehabilitation, and providing evidence for medical legal purposes. Electromyographic findings most often serve as an adjunct to a thorough clinical evaluation of the patient. The electrophysiological data obtained may help support or rule out a specific clinical diagnosis.

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The sensory and motor deficits of the CNS are varied, depending on the etiologic factors and the structures involved. Nevertheless, the clinical picture is predictable, provided one has an adequate knowledge of the neuroanatomy and the functions of the different fiber tracts, nuclei, and other specific regions of the brain and spinal cord. The purpose of this section is to provide an overall view of the sensory and motor deficits of the CNS, which will enable the clinician to treat these patients in a more objective and effective manner. Etiologically, the diseases affecting the CNS can be grouped under the following categories: congenital, traumatic, inflammatory, neoplastic, and degenerative. Congenital conditions usually manifest in infancy and childhood. Examples are hydrocephalus, spina bifida, and Arnold-Chiari malformation. There are a host of other conditions, but the discussion in this article is confined to the more common entities. Traumatic conditions such as cerebral concussion, contusion, laceration, hematomas--extradural, subdural, or intracerebral--and spinal cord injuries can occur in any age group, though their incidence is higher during the more active period of life (20 to 35 years). Automobile accidents are by far the most common etiologic factor for the traumatic lesions. Others, such as falls, gunshot and stab wounds, and so forth account for the remainder. Among the inflammatory conditions, three conditions are important: brain abscess, meningitis, and transverse myelitis. Though brain abscess develops by direct extension from an adjacent focus of infection, often it forms as a result of metastatic infection, chiefly from lung abscess or bronchoectasis. It behaves more like an intracranial space occupying lesion. Of the various types of meningitis, meningococcal meningitis is the commonest. Transverse myelitis may be caused by viruses or bacteria. The clinical picture resembles that of spinal cord injury. Neoplasms of the brain and spinal cord present a wide and varied spectrum. They may be benign or malignant. Meningioma and neurofibroma are essentially benign lesions. Malignant tumors can be primary or secondary. Gliomas and specifically astrocytomas are the commonest primary malignant tumors. The commonest sites of metastatic tumors are lung, breast, kidney, and gastrointestinal tract. The clinical picture will depend on the location of the tumor and the structures pressed upon or infiltrated. Any age group can be affected. Many of the malignant tumors are slowly and relentlessly progressive. Complete surgical extirpation where possible, followed by radiation therapy, is the treatment of choice. Chemotherapy has not been of much benefit.(ABSTRACT TRUNCATED AT 400 WORDS)

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CVA comprises a large number of clinical entities, depending on the site of infarction in the brain. Accurate evaluation of deficits in the patient's sensory and/or motor systems and the patient's intellectual status are paramount in establishing realistic rehabilitation goals. With respect to the motor system, two types of voluntary movement may occur. These include synergistic or pattern movement and selective movement. Spasticity in the affected lower extremity may result in a variety of lower-extremity deformities and contractures. Those most commonly encountered include hip flexion and adduction contracture, inadequate knee flexion and knee flexion contracture, and ankle equinus, varus, and equinovarus. Correct evaluation of deformities may be aided by the use of poly-EMG analysis and evaluation after nerve block or motor point blocks. In hemiplegic gait dysfunction, the basic requirements for functional ambulation include (1) ability to maintain standing balance; (2) voluntary hip flexion; (3) leg stability; and (4) ability to follow instructions and adequate motivation. Often a hemiplegic patient can be trained to ambulate if an adequate extensor synergy pattern develops, since mass extension can provide stability of the leg for weight bearing. Medical rehabilitative management of the CVA patient includes early mobilization, restorative exercises (including neuromuscular facilitation techniques), measures to prevent or correct contractures, the use of AFOs, and occasionally functional electrical stimulation. Orthopedic management of deformities in CVA is indicated where conservative measures fail. Surgical procedures seek to alter the forces causing shortening of the muscles and tendons. Hence, the most commonly performed surgical procedures include (1) tendon lengthening or release; (2) soft-tissue release; and (3) tendon transfer. Surgery for hip contractures is not common; however, occasional release of hip flexors is indicated when hip flexion contracture impedes ambulation or prone lying. Inadequate knee flexion, caused by dysphasic quadriceps contraction, can be corrected by release of the vastus medialis and rectus femoris muscles. Distal hamstring tendon release with or without knee joint capsule release is the surgical procedure of choice for severe knee flexion contractures. Surgical correction of an equinus deformity is by TAL, with or without neurectomy of tibial nerve branches to the gastrocsoleus muscles. Severe ankle varus may require a SPLATT procedure. Surgery for equinovarus includes the combined surgery for both equinus and varus (that is, TAL and SPLATT procedures). Toe curling is corrected by toe flexor releases.(ABSTRACT TRUNCATED AT 400 WORDS)

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The rehabilitative course for patients who have suffered vertebral-basilar vascular lesions is often interrupted by intermittent episodes of increasing dizziness, nausea, vomiting, and ataxia. Since CT studies of the brain do not always visualize these lesions reliably, the rehabilitation specialist has been without a diagnostic tool to distinguish between progressive and stable vertebral-basilar system infarctions. Magnetic resonance imaging (MRI) offers a safe, noninvasive, sensitive means of monitoring vascular lesions in the posterior fossa. The purpose of this study was to use MRI to evaluate patients with suspected vertebral-basilar vascular lesions. In three patients studied, MRI was superior to CT scan. Advantages of MRI included lack of artifact due to bone scattering from ionizing radiation, ability to image directly in the sagittal plane, visualization and localization of pathologically smaller lesions, and potential for performing serial studies without exposing patients to large doses of radiation. In each case, MRI data yielded valuable adjunctive information that aided further rehabilitation evaluation and management. We conclude that MRI may be a useful diagnostic and prognostic tool in evaluating and managing rehabilitation patients with vascular lesions involving the vertebral-basilar system.

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Brainstem auditory evoked potentials (BAEPs) were used to monitor eight neurosurgical procedures involving posterior fossa tumors to assist the neurosurgeon in preservation of hearing postoperatively. The technique included placement of recording electrodes over the Cz (vertex) and both earlobes. Stimulation was accomplished intraoperatively with a specifically designed intraauricular click stimulator that did not interfere with surgical access to the suboccipital region. Continuous BAEP recording was performed with particular attention to the sequence of preincision, opening of the dura, tumor mobilization, tumor excision, and closure. Absolute latencies and interpeak latencies of all five waves were recorded when possible. In three patients BAEPs were not significantly altered intraoperatively, and hearing was preserved postoperatively. In another three patients the acoustic nerve was severed during surgery and intraoperative monitoring was discontinued. In the remaining two patients medical complications arose intraoperatively, and significant irreversible changes in BAEP were observed despite no gross anatomical damage to the acoustic nerve. Both of these patients experienced postoperative hearing loss. These two cases illustrated some of the BAEP abnormalities that occurred during surgery. Difficulties during the procedures included electrical noise and interference, use of a bipolar cautery device, and unclear wave forms. Solutions for these difficulties were braiding the electrodes and using extra ground electrodes and a spike suppressor; switching off the evoked potential equipment when the bipolar cautery device was in use; and increasing repetitions and changing click intensity and polarity, respectively. Monitoring BAEPs in posterior fossa surgery can be accomplished with presently available equipment and may aid the neurosurgeon in preserving or minimizing injury to auditory pathways and adjacent structures.(ABSTRACT TRUNCATED AT 250 WORDS)

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Clinically significant thromboembolic disease originating from the paralyzed leg of hemiplegic patients can occur unexpectedly and may affect morbidity and mortality in the rehabilitation setting. Impedance plethysmography (IPG), a simple, noninvasive technique, can accurately reveal deep vein thrombosis (DVT) in the large veins of the thigh. IPG studies were performed on the lower extremities of 20 hemiplegic patients considered at high risk for DVT. Each patient had one or several of the following potential risk factors: mild swelling, vague leg discomfort, loss of sensation, poor or absent muscle power at the ankle, at least one week of complete bedrest, repeated minor trauma. None of the patients had major signs or symptoms of DVT at the time of testing (ie, severe pain and tenderness, increased temperature or redness, a palpable venous cord, or positive Homans' sign). Seven patients had an abnormal IPG in the paralyzed lower limb and DVT was confirmed in each case by venography. After appropriate anticoagulation therapy, the seven patients resumed their rehabilitation programs. It was concluded that IPG can be successfully used in the early detection of DVT in high-risk hemiplegic patients, thus leading to prompt medical management, reduced morbidity and mortality, and improved rehabilitation outcome.

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Progressive supranuclear palsy (PSP) is a distinct clinicopathologic entity characterized by supranuclear ophthalmoplegia, pseudobulbar palsy, axial dystonia in extension, and subcortical dementia. Although relatively rare, PSP is disabling, thus rehabilitation techniques and management are indicated in nearly every case. This report describes the neurologic presentation, rehabilitation management, and outcome of treatment of a patient with PSP during a 12-month period. The patient required thorough neuromuscular, neuropsychological, speech, swallowing, vision, and social service evaluations prior to the implementation of a rehabilitation program. Therapeutic rehabilitation techniques focused on limb coordination activities, tilt board balancing, ambulation activities, and activities to improve route finding and visual scanning ability. Prism lenses were introduced to compensate for deficits in vertical eye movements. Treatment improved the patient's functional status. Later, as the patient's neurologic status deteriorated, it became necessary to educate the family and caretakers in the ongoing rehabilitation management of the patient.

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Electrophysiologic parameters of the medial dorsal cutaneous (MDC) and the sural nerves were analyzed in 119 diabetic patients with clinical signs and symptoms of neuropathy. Fifty-five patients were insulin dependent (ID), mean age 47.4, and 64 were non-insulin dependent (NID), mean age 55.2. Using age-adjusted criteria for the sensory nerve action potential (SNAP) amplitude and for conduction velocity (CV), the relative sensitivity of each parameter and the extent of concordance between them within each diabetic group were investigated. In mild neuropathy it was found that: 1) 43% (ID group) and 39% (NID group) had abnormalities of both parameters in both nerves; 2) 10% of MDC nerves and 12% of sural nerves were normal; 3) only 48% of the nerves studied had abnormalities of both parameters; 4) single parameter abnormalities were found with equal frequency. It is concluded that: 1) there is a high degree of concordance between corresponding parameters of the two nerves within each diabetic group; similar abnormalities occur within each group but are manifested at an earlier age in the ID group. 2) In mild diabetic neuropathy, (A) greater than 10% of sensory nerves studied may be normal; (B) less than 50% of nerves studied will have abnormalities of both parameters; (C) since single parameter abnormalities occur with almost equal frequency, both parameters should be taken into account for correct interpretation; (D) the evaluation of both parameters in two lower extremity sensory nerves increases diagnostic sensitivity.

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This study evaluated speech rehabilitation outcome and length of training needed for laryngectomized patients who underwent the Blom-Singer tracheoesophageal (TE) puncture procedure. Preoperative patient selection criteria included: 1) acceptable stoma size, 2) adequate motivation and manual dexterity, 3) absence of constrictor spasm. Training focused on coordination of breath control, articulation, muscle relaxation, and proper handling and maintenance of the "duckbill" prosthesis. Speech intelligibility in 12 patients was evaluated following the completion of their speech rehabilitation program, using the CID Everyday Sentences. Each patient was videotaped; the tape then was presented to unbiased listeners who recorded the sentences. The median percentage of intelligibility for the 12 patients was 89.5%; only one patient had a median score less than 60%. The mean length of formal training for the group was only 3.2 hours (range 1 to 7 hours). The percentage of patients attaining speech and the quality of their speech intelligibility was found to be higher than with esophageal speech, which is both time consuming and often difficult to learn. TE puncture followed by proper fitting and training in voice prosthesis usage improves speech rehabilitation outcome for the laryngectomized patient.

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Lithium toxicity can produce persistent and possibly permanent neurologic damage involving multiple areas of the nervous system, often including the cerebellum. Such cases, though rare, may continue to occur since lithium salts are widely used. In this report we describe the neurologic presentation, rehabilitation management, and outcome of treatment in such a patient. Her persistent neurologic syndrome was dominated by features of cerebellar dysfunction. Deficits in speech, swallowing, activities of daily living, transfers, and ambulation were identified and a rehabilitation program was implemented. Therapeutic rehabilitative techniques focused on compensatory mechanisms for ataxia and incoordination. Though her basic neurologic status did not change substantially, she did respond well to rehabilitative measures with significant functional gains and the patient was returned to her prior living arrangement.

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This report describes an entrapment syndrome of the superficial peroneal nerve terminal sensory branches. Two patients presented with numbness and tingling of the foot dorsum. These symptoms increased with activity such as walking, running, and squatting. The signs were 1) a decrease in sensation to light touch and pin prick on the foot dorsum over the cutaneous distribution of the nerve with sparing of the first web space; 2) a soft tissue bulge over the anterolateral aspect of the leg approximately 10 cm above the lateral malleolus; 3) a Tinel sign over the bulge; 4) an increase in the size of the bulge either with resisted ankle dorsiflexion or weight bearing; and 5) tenderness over the bulge or distally over the terminal sensory branches of the superficial peroneal nerve. Electrodiagnostic studies revealed an unrecordable evoked response or a prolonged distal latency of the terminal sensory branches of the superficial peroneal nerve. Treatment consisted of surgical decompression of the nerve at the bulge by fasciotomy. Patients responded with complete symptomatic relief. To provide accurate treatment, the diagnosis of entrapment syndrome of the superficial peroneal nerve terminal sensory branches must be differentiated from other causes of pain and numbness in the ankle area.

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Techniques for performing antidromic conduction velocity studies on forearm sensory nerves were evaluated in 157 healthy subjects from 17 to 80 years of age. The lateral antebrachial cutaneous nerve (LABCN) and the medial antebrachial cutaneous nerve (MABCN) were studied in the same upper extremity at a distance of 14 cm. The mean values for LABCN were amplitude 18.9 microV, latency to peak 2.8 ms and conduction velocity (CV) 61.5 m/s; for MABCN, amplitude 11.4 microV, latency to peak 2.7 ms and CV 62.7 m/s; and for median nerve, CV 62.3 m/s. SNAPs were obtained in 98% of subjects for each forearm sensory nerve. Age-related changes in the MABCN and LABCN were small, but included a decreased number of high value SNAP amplitudes and CVs with advancing age, whereas values for the median nerve showed a slight overall decrease with age. Sex effects were negligible. It is concluded that: LABCN and MABCN conduction studies can be performed with equal and high reliability using standard techniques and the same constant distance; The amplitude of the LABCN tends to be larger than that of the MABCN (76% of subjects); In some subjects MABCN studies are technically more difficult to perform than LABCN studies; Forearm sensory nerve studies may be used in addition to median nerve sensory studies in the evaluation of peripheral neuropathy, brachial plexopathy and local neuropathic conditions.

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This study investigates the sensitivity and usefulness of medial dorsal cutaneous nerve (MDCN) conduction studies in patients with peripheral neuropathy. Two hundred twenty-three patients with clinical signs and symptoms of peripheral neuropathy in their lower extremities were evaluated. Nerve conduction velocity studies of the MDCN were compared to those of the sural and peroneal motor nerves. Fifty-eight percent of the patients had no measurable sensory nerve action potential (SNAP) from either the MDCN or sural nerve or both, indicating moderate to severe neuropathy. Of the remaining patients with mild neuropathy, 12% had a normal sural nerve and an abnormal MDCN, whereas 7% had a normal MDCN and an abnormal sural nerve. Fifty-one percent of the mild cases had normal peroneal motor nerve studies. It is concluded that the MDCN is equal to the sural nerve as a sensitive indicator in all stages of peripheral neuropathy; in mild or early neuropathy approximately 12% of patients will have normal sural nerve studies; and it is important to examine both distal sensory nerves of the leg. Addition of the MDCN study to the standard sural study increases diagnostic accuracy in mild peripheral neuropathy from 88% to nearly 100%.

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A method for obtaining antidromic conduction velocities in the sensory branches of the superficial peroneal nerve at the level of the ankle was evaluated. An essential prerequisite for the study of this nerve is knowledge of its exact topography. The method included the placing of surface recording electrodes directly over the branches of the nerve and stimulating the superficial peroneal nerve at the anterolateral aspect of the leg. The right lower extremity of 80 normal subjects was evaluated. The mean values obtained from the medial dorsal cutaneous branch at a distance of 14cm were 2.8 +/- 0.3 msec, 51.2 +/- 5.7 msec, 18.3 microV for the latency to onset of negative deflection, conduction velocity and amplitude, respectively. Similar values were obtained from studies of the intermediate dorsal cutaneous branch. In ease of performance and in reliability, sensory conduction studies in the branches of the superficial peroneal nerve were found to be equal to those of the sural nerve and superior to those of the saphenous nerve. The described technique should be helpful in the electrodiagnostic evaluation of peripheral neuropathy as well as of local neuropathic conditions and entrapment syndromes involving the peroneal nerve or its sensory branches.

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