Central conduction abnormalities after electrical injury

Delayed Spinal Cord Injury From Electrical Burns: Two Cases

Spinal cord injury has been described in only 2% to 5% of electrical injuries. When its presentation is delayed for several days to weeks after the initial injury, recovery is not the rule. Herein, we describe two patients who developed spinal cord injury from electrical burns. Case 1: A 60-year-old male presented with a 40% TBSA after contacting a power line. On hospital day 6, he developed lower extremity weakness that progressed to flaccid paralysis. Case 2: A 58-year-old male sustained a 9% TBSA high-voltage injury. On hospital day 2, he started to have progressive weakness of his lower extremities that progressed to flaccid paralysis. Neither case was judged to have experienced additional significant trauma. Neurological complications after electrical injuries are protean. Delayed spinal cord injury is rare and associated with variable degrees of recovery. Neurological follow-up with rehabilitation is essential for a successful recovery.

Neurophysiological assessment of fatigue in electrical injury patients

To investigate for the presence of central and peripheral physiological fatigue in electrical injury (EI) patients with experiential fatigue. Eight EI patients and eight age-matched healthy volunteers were recruited. Motor evoked potentials (MEP) following transcranial magnetic stimulation (TMS) and M-waves from ulnar nerve stimulation at the wrist were measured from the right abductor digiti minimi. Fatigue was induced by 2 min of maximal voluntary contraction, and subjects were followed for 15 min of recovery. The experiment was performed twice for each subject. In one of the two sessions (randomly assigned), a blood pressure (BP) cuff was inflated during the first 75 s of recovery period to prolong muscle ischemia. Baseline measures showed no difference in central and peripheral conduction times. Cortical silent period was prolonged in patients compared to controls with no differences in abduction force. Decrement of MEP amplitude with consecutive TMS pulses was observed in the post-recovery period only with EI patients who had prolonged muscle ischemia induced by the BP cuff. The post-exercise M-wave area during contraction was significantly higher for patients. Prolonged cortical silent period in EI patients suggests that they had increased GABAB receptor-mediated cortical inhibition. The ischemia-induced decrement in consecutive MEP amplitudes post-exercise demonstrates greater physiological fatigue in EI patients after exercise. The greater increase in M-wave area of EI patients post-exercise suggests larger decrease in conduction velocity of muscle action potentials with exercise. These findings provide preliminary physiological correlates for increased central and peripheral fatigue in EI patients with experiential fatigue.

Analysis of high-voltage electrical spinal cord injury using diffusion tensor imaging

The aim of this study was to investigate spinal cord injury (SCI) on the basis of diffusion tensor imaging (DTI) in patients with high-voltage electrical injury. We recruited eight high-voltage electrical injury patients and eight healthy subjects matched for age and sex. DTI and central motor conduction time were acquired in both the patient and control groups. We obtained DTI indices according to the spinal cord levels (from C2 to C7) and cross-section locations (anterior, lateral, and posterior). Fractional anisotrophy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) were compared between the two groups; additionally, they were compared in relation to spinal cord level and cross-section location. In the patient group relative to the control group, the FA value decreased and the MD and RD values increased in all of the regions of interest (ROI) with statistical significance (p < 0.05). In the patient group, particularly in the ROIs of the anterior spinal cord compared with the lateral and posterior spinal cords, the FA value decreased with statistical significance (p < 0.05). The DTI indices did not differ by level. DTI revealed the change of diffusion in the spinal cords of patients with high-voltage electrical injury, and corroborated the pathophysiology, myelinopathy and typical anterior spinal cord location of high-voltage electrical SCI already reported in the literature.

Transcranial magnetic stimulation can diagnose electrical burn-induced myelopathy

INTRODUCTION

We conducted motor- and sensory-evoked potential analyses and investigated their diagnostic value in differentiating between electrical burns without evidence of neurologic injury and those with clinical evidence of myelopathy.

METHODS

We studied high-voltage electrical burn injury patients with lower extremity weakness and evidence of myelopathy and those without any evidence of neurological complications. Motor-evoked potentials (MEPs), somatosensory-evoked potentials (SEPs), and MRI studies of the spinal cord, as well as transcranial magnetic stimulations, were performed. The central motor conduction time (CMCT) was also calculated.

RESULTS

The upper limb MEP and upper and lower limb SEP variables did not statistically differ between the 2 groups. The CMCT and total motor conduction time recorded in the lower limb were delayed in the burn myelopathy group. MRI revealed no abnormal signal changes in myelopathy patients.

CONCLUSION

Our study demonstrates that MEP is useful in identifying myelopathy in patients who have sustained high-voltage electrical burns.

Corticospinal tract dysfunction and development of amyotrophic lateral sclerosis following electrical injury

The causal relationship between electrical injury and development of amyotrophic lateral sclerosis (ALS) remains controversial. We describe the case of a 25-year-old man who developed ALS after a severe electrical injury. Cerebral magnetic resonance imaging (MRI) demonstrated hyperintensities involving the corticospinal tract. Functional testing with transcranial magnetic stimulation established that the motor cortex was relatively inexcitable. In addition, there were features of denervation on electromyography and muscle biopsy that supported concomitant lower motor neuron findings and the diagnosis of ALS.

Myelopathy and amnesia following accidental electrical injury

OBJECTIVE

Documentation of MRI and neurophysiological changes following accidental electrical injury.

SETTING

Tertiary care referral teaching hospital at Lucknow, India.

RESULTS

A 30-year-old lady developed amnesia and spastic paraparesis with loss of pin prick sensation below the second thoracic spinal segment following electrocution. Her spinal MRI was normal and cranial MRI revealed T2 hyperintensity in the right putamen. Peroneal, sural and electromyography were normal. Tibial central sensory conduction time was normal but central motor conduction time to lower limbs and right upper limb was prolonged.

CONCLUSION

Neurophysiological study and MRI may help in understanding the pathophysiological basis of neurological sequelae following electrical injury.

Injury by electrical forces: pathophysiology, manifestations, and therapy

The pathogenesis and pathophysiologic features of electrical injury are more complex than once thought. The relative contributions of thermal and pure electrical damage depend on the duration of electric current passage, the orientation of the cells in the current path, their location, and other factors. If the contact time is brief, nonthermal mechanisms of cell damage will be most important and the damage is relatively restricted to the cell membrane. When contact time is much longer, however, heat damage predominates and the whole cell is affected directly. These parameters also determine the anatomic tissue distribution of injury. Damage by Joule heating is not known to be dependent on cell size, whereas larger cells are more vulnerable to membrane breakdown by electroporation. Cells do survive transient plasma membrane rupture under appropriate circumstances or if therapy is instituted quickly. If membrane permeabilization is the primary cellular pathologic condition, then injured tissue may be salvageable and the challenge for the future is to identify a technique to reseal the damaged membranes promptly. Present standards of care for electrical injury require a fully staffed and well-equipped intensive care unit, available operating suites, and the availability of the full range of medical specialists. Major teaching hospitals with burn centers may be the ideal setting for the treatment of an electrical trauma victim. After the initial resuscitation, efforts are directed primarily towards preventing additional tissue loss mediated through the compartment syndrome, compressive neuropathies, or the presence of necrotic tissue. Renal and cardiac failure caused by the release of intracellular muscle contents into the circulation must be prevented. Attention can then be directed towards maximizing tissue salvage and preventing late skeletal and neuromuscular complications. Reconstructive procedures that transfer healthy tissue from a distance are necessary to optimize the functional value of the remaining tissue. Finally, unless the patient is rehabilitated psychologically, the real benefit from other sophisticated care will not be fully realized. These goals are important throughout the acute care of the patient. In the future, new guidelines for treating electrical trauma will be based on a clearer understanding of the relevant pathophysiologic features. These strategies will rely on improved diagnostic imaging and on reversing the fundamental problem of cell membrane damage. Moreover, complex biochemical and organ system pathophysiologic interactions will require careful management. If successful, research efforts presently underway should improve the prognosis of victims after electrical trauma.