Lawrence R. Robinson

Traumatic injury to peripheral nerves

This article reviews the epidemiology and classification of traumatic peripheral nerve injuries, the effects of these injuries on nerve and muscle, and how electrodiagnosis is used to help classify the injury. Mechanisms of recovery are also reviewed. Motor and sensory nerve conduction studies, needle electromyography, and other electrophysiological methods are particularly useful for localizing peripheral nerve injuries, detecting and quantifying the degree of axon loss, and contributing toward treatment decisions as well as prognostication.

Cognitions, coping and social environment predict adjustment to phantom limb pain.

&NA; Biopsychosocial models of chronic pain hypothesize a role for psychological and environmental factors in adjustment to chronic pain. To test the utility of such models for understanding phantom limb pain, 61 persons with recent amputations were administered measures of average phantom limb pain intensity, pain interference, depression, pain coping use, pain cognitions and appraisals, and social environmental variables 1 month post‐amputation, and the measures of pain intensity, pain interference, and depression again 5 months later. Multiple regression analyses showed that the psychosocial predictors made a statistically significant contribution to the concurrent prediction of average phantom limb pain, pain interference, and depression at the initial assessment, and a significant contribution to the prediction of subsequent change in pain interference and depression over the course of 5 months. The results support the utility of studying phantom limb pain from a biopsychosocial perspective, and identify specific biopsychosocial factors (e.g., catastrophizing cognitions, social support, solicitous responses from family members, and resting as a coping response) that may play an important role in adjustment to phantom limb pain.

Predictive value of somatosensory evoked potentials for awakening from coma.

ObjectivesA systematic review of somatosensory evoked potentials performed early after onset of coma, to predict the likelihood of nonawakening. The pooled results were evaluated for rates of awakening, confidence intervals, and the possibility of rare exceptions. Data SourcesForty-one articles reporting somatosensory evoked potentials in comatose patients and subsequent outcomes, from 1983 to 2000. Study SelectionStudies were included if they reported coma etiology, age group, presence or absence of somatosensory evoked potentials, and coma outcomes. Data ExtractionWe separated patients into four groups: adults with hypoxic-ischemic encephalopathy, adults with intracranial hemorrhage, adults and adolescents with traumatic brain injury, and children and adolescents with any etiologies. Somatosensory evoked potentials were categorized as normal, abnormal, or bilaterally absent. Outcomes were categorized as persistent vegetative state or death vs. awakening. Data SynthesisFor each somatosensory evoked potential result, rates of awakening (95% confidence interval) were calculated: adult hypoxic-ischemic encephalopathy: absent 0% (0%–1%), abnormal 22% (17%–26%), normal 52% (48%–56%); adult intracranial hemorrhage: absent 1% (0%–4%), present 38% (27%–48%); adult-teen traumatic brain injury: absent 5% (2%–7%), abnormal 70% (64%–75%), normal 89% (85%–92%); child-teen: absent 7% (4%–10%), abnormal 69% (61%–77%), normal 86% (80%–92%). ConclusionsSomatosensory evoked potential results predict the likelihood of nonawakening from coma with a high level of certainty. Adults in coma from hypoxic-ischemic encephalopathy with absent somatosensory evoked potential responses have <1% chance of awakening.

Psychosocial predictors of long-term adjustment to lower-limb amputation and phantom limb pain

Purpose: To evaluate the utility of a biopsychosocial model to predict long-term adjustment to lower-limb amputation and phantom limb pain (PLP). Method: One month after lower-limb amputation, 70 participants completed measures of PLP intensity, cognitions (catastrophizing, perceived control over pain), coping (pain-contingent rest), social environment (social support, solicitous responding), and functioning (pain interference, depressive symptoms). The measures of functioning were administered again at 1- and 2-years post-amputation. Multiple regression analyses were used to examine the ability of the psychosocial variables at 1-month post-amputation to predict changes in the functioning measures over time. Results: The psychosocial variables at 1-month post-amputation, controlling for initial PLP intensity, accounted for 21% of the variance in change in depressive symptoms at 1-year (p < 0.05), and 27% and 22% (ps < 0.01 and 0.05, respectively) of the variance in change in pain interference and depressive symptoms, respectively, at 2-years post-amputation. Catastrophizing and social support were associated with decreases (improvement) in both criterion measures, while solicitous responding was associated with increases (worsening) in both measures. Discussion: The findings support a biopsychosocial model of long-term adjustment to amputation and PLP. In addition, results suggest that some psychosocial variables are more important than others for predicting adjustment, providing important implications for early interventions after amputation.

AAEM minimonograph #47: Normative data in electrodiagnostic medicine

This article reviews, without mathematics, the important principles governing the acquisition and use of normative data in electrodiagnostic medicine. Common flaws in neurophysiological normative data include vague clinical criteria for establishing freedom from disease, samples that are too small and inadequately stratified, and application of Gaussian statistics to non‐Gaussian variables. Other problematic issues concern the trade‐off between permissible false‐positivity and false‐negativity in defining the limits of normative from sample data, test‐retest variability, and the use of multiple independent test measurements in each electrodiagnostic examination. The following standards for normative data are proposed: (1) standardized objective determination of freedom from disease; (2) appropriately large sample of normal subjects; (3) proportional statification of normal subjects for known relevant variables; (4) test of Gaussian fit for application of Gaussian statistics; and (5) data presentation by percentiles when Gaussian fit is in doubt. Many existing normative studies in clinical neurophysiology do not meet these standards. High‐quality normative data, readily accessible, is essential for the accurate electrodiagnosis of neuromuscular diseases.

Recommendations of the Neurolaryngology Study Group on laryngeal electromyography

The Neurolaryngology Study Group convened a multidisciplinary panel of experts in neuromuscular physiology, electromyography, physical medicine and rehabilitation, neurology, and laryngology to meet with interested members from the American Academy of Otolaryngology Head and Neck Surgery, the Neurolaryngology Subcommittee and the Neurolaryngology Study Group to address the use of laryngeal electromyography (LEMG) for electrodiagnosis of laryngeal disorders. The panel addressed the use of LEMG for: 1) diagnosis of vocal fold paresis, 2) best practice application of equipment and techniques for LEMG, 3) estimation of time of injury and prediction of recovery of neural injuries, 4) diagnosis of neuromuscular diseases of the laryngeal muscles, and, 5) differentiation between central nervous system and behaviorally based laryngeal disorders. The panel also addressed establishing standardized techniques and methods for future assessment of LEMG sensitivity, specificity and reliability for identification, assessment and prognosis of neurolaryngeal disorders. Previously an evidence-based review of the clinical utility of LEMG published in 2004 only found evidence supported that LEMG was possibly useful for guiding injections of botulinum toxin into the laryngeal muscles. An updated traditional/narrative literature review and expert opinions were used to direct discussion and format conclusions. In current clinical practice, LEMG is a qualitative and not a quantitative examination. Specific recommendations were made to standardize electrode types, muscles to be sampled, sampling techniques, and reporting requirements. Prospective studies are needed to determine the clinical utility of LEMG. Use of the standardized methods and reporting will support future studies correlating electro-diagnostic findings with voice and upper airway function.

Diabetes and diabetes risk factors in second- and third-generation Japanese Americans in Seattle, Washington

In Seattle, Washington, the prevalence of diabetes was 20% in second-generation (Nisei) Japanese-American men and 16% in Nisei women 45-74 years old, while the prevalence of impaired glucose tolerance (IGT) was 36% in Nisei men and 40% in Nisei women. Hyperglycemia was less and duration of diabetes shorter in women. Related to diabetes and IGT in Nisei were higher fasting plasma insulin levels and central (visceral) adiposity. Prevalence of diabetes was low among the younger (34-53 years old) third-generation (Sansei) men and women. Among self-reported non-diabetic Sansei, however, prevalence of IGT was 19% in men and 29% in women, and IGT was associated with both increased fasting plasma insulin levels and more visceral fat, suggesting that many Sansei are at risk of future diabetes. An important lifestyle factor in the development of NIDD in Japanese Americans appeared to be dietary saturated (animal) fat. Another factor may be physical inactivity. In Japanese-American women, menopause also appeared to be an important risk factor. These risk factors may be related to fostering the accumulation of visceral fat and the development of insulin resistance. Five-year follow-up examinations performed in non-diabetic Nisei men and women have yielded additional information concerning the prognosis of IGT. Of those women who were IGT at baseline, 34% were diabetic at follow-up while 17% returned to normal. In men who had been IGT at baseline, 18% were diabetic at follow-up while 36% returned to normal. Over the 5-yr follow-up interval, proportionally more women progressed from normal to IGT (54%) then went from IGT to normal (17%). For men, roughly equal proportions went from normal to IGT (37%) as from IGT to normal (36%). It would therefore appear that greater proportions of Nisei women are progressing to IGT and to NIDD than are Nisei men. This observation may be related to the increased risk of developing central obesity and insulin resistance following menopause. Prevalence of cardiovascular disease (hypertension, peripheral vascular disease, and/or coronary heart disease) was increased in Japanese Americans with IGT and NIDD. Neuropathy and retinopathy were associated only with NIDD.

Trial of amitriptyline for relief of pain in amputees: results of a randomized controlled study.

OBJECTIVE To evaluate whether amitriptyline is more effective than placebo in improving phantom limb pain or residual limb pain. DESIGN Randomized controlled trial of amitriptyline for 6 weeks. SETTING University hospital. PARTICIPANTS Thirty-nine persons with amputation-related pain lasting more than 6 months. INTERVENTION Six-week trial of amitriptyline (titrated up to 125 mg/d) or an active placebo (benztropine mesylate). MAIN OUTCOME MEASURES Analyses were conducted to examine whether there was a medication group effect on the primary outcomes (average pain intensity) and secondary outcome measures (disability, satisfaction with life, handicap). RESULTS No significant differences were found between the treatment groups in outcome variables when controlling for initial pain scores. CONCLUSIONS Our findings do not support the use of amitriptyline in the treatment of postamputation pain.

Efficacy of gabapentin in treating chronic phantom limb and residual limb pain.

Twenty-four adults with phantom limb pain (PLP) and/or residual limb pain (RLP) participated in a double-blind crossover trial. Participants were randomly assigned to receive gabapentin or placebo and later crossed over to the other treatment, with a 5-week washout interval in which they did not receive medication. Gabapentin was titrated from 300 mg to the maximum dose of 3,600 mg. Measures of pain intensity, pain interference, depression, life satisfaction, and functioning were collected throughout the study. Analyses revealed no significant group differences in pre- to posttreatment change scores on any of the outcome measures. More than half of the participants reported a meaningful decrease in pain during the gabapentin phase compared with about one-fifth who reported a meaningful decrease in pain during the placebo phase. In this trial, gabapentin did not substantially affect pain. More research on the efficacy of gabapentin to treat chronic PLP and RLP is needed.

Use of somatosensory-evoked potentials and cognitive event-related potentials in predicting outcomes of patients with severe traumatic brain injury.

Lew HL, Dikmen S, Slimp J, Temkin N, Lee EH, Newell D, Robinson LR: Use of somatosensory-evoked potentials and cognitive event-related potentials in predicting outcomes of patients with severe traumatic brain injury. Am J Phys Med Rehabil 2003;82:53–61. Objective This study was performed to evaluate the usefulness of somatosensory-evoked potentials (SEPs) and cognitive event-related potentials (ERPs) in predicting functional outcomes of severe traumatic brain injury patients. Design Prospective study of 22 patients with severe traumatic brain injury. Demographic information, Glasgow Coma Scale, and electrophysiologic measurements were recorded. Functional outcomes, as quantified by the Glasgow Outcome Scale–Extended, were obtained. Results Bilateral absence of median nerve SEP was strongly predictive of the worst functional outcome. The specificity and positive predictive value of absent SEP for predicting death or persistent vegetative state at 6 mo after traumatic brain injury were as high as 100%. If the definition of unfavorable outcome was expanded to include Glasgow Outcome Scale–Extended 1–4, absence of ERP was equivalent to the absence of SEP in specificity and positive predictive value. On the other hand, normal ERPs showed higher sensitivity and negative predictive value for prognosticating the best outcomes compared with normal SEPs. If the definition of favorable outcome was expanded to include Glasgow Outcome Scale–Extended 5–8, ERP was still superior to SEP for prognosticating good outcome. Interestingly, the highest sensitivity and negative predictive value for favorable outcomes were associated with the presence of any discernible waveform. Conclusions Although median nerve SEP continues to make reliable prediction of ominous outcome in severe traumatic brain injury, the addition of the speech-evoked ERPs may be helpful in predicting favorable outcomes. The strength of the latter test seems to complement the weakness of the former.