Lyell K. Jones

Natural history of exertional rhabdomyolysis: a population-based analysis.

Exertional rhabdomyolysis is a potentially catastrophic syndrome with an incidence and rate of recurrence that are unknown. In this study patients with rhabdomyolysis were identified retrospectively from the Wilford Hall Medical Center records. A population‐based analysis was performed on exertional rhabdomyolysis patients enrolled in basic military training. A retrospective cohort was analyzed for rate and risks of recurrence. Of 177 rhabdomyolysis patients, 63 were exertional in mechanism. The rate of renal failure was lower in exertional rhabdomyolysis patients (odds ratio 0.45, 95% confidence interval 0.22–0.95, P = 0.04). There were 44 cases of exertional rhabdomyolysis from a population of 198,399 total military trainees over the study period, or 22.2 cases per 100,000 per year. A cohort of 22 exertional rhabdomyolysis patients was followed for a mean of 31.2 months, with only 1 recurrence (recurrence risk of 0.08% per person per year). Exertional rhabdomyolysis is associated with lower rates of complications than other causes of rhabdomyolysis. Among young, physically active patients, the incidence of exertional rhabdomyolysis is low, as is the risk of recurrence. Muscle Nerve, 2010

Cramp-fasciculation syndrome in patients with and without neural autoantibodies

Introduction: We investigated the clinical, electrophysiological and neural autoantibody characteristics in cramp‐fasciculation syndrome (CFS) patients. Methods: We reviewed Mayo Clinic records from 2000 to 2011 to identify clinically defined CFS patients who underwent neural autoantibody testing. Stored sera of patients who tested positive for antibodies to voltage‐gated potassium channel complex (VGKC complex) were analyzed further for leucine‐rich glioma‐inactivated 1 (LGI1) or contactin‐associated protein‐2 immunoglobulin G (CASPR2‐IgG) antibodies. Results: Thirty‐seven patients were identified. Twelve were seropositive for neural autoantibodies. Clinical manifestations were similar in seropositive and seronegative patients, although central and autonomic neuronal hyperexcitability symptoms were more common in seropositive cases. No patients had a malignancy. Repetitive tibial nerve stimulation at 10 Hz revealed longer afterdischarges in seropositive patients. Two of 7 patients with VGKC‐complex autoimmunity demonstrated LGI1 or CASPR2‐IgG antibodies. Only 2 of 12 seropositive patients required immunotherapy. Conclusions: VGKC‐complex autoimmunity occurs in a minority of CFS patients. Antibody positivity was associated with extramuscular manifestations, typically without malignancy. Target antigens within the VGKC complex remain unknown in most patients. Muscle Nerve 49:351–356, 2014

The impact of ischemic intervals on neuromuscular recovery in a porcine (Sus scrofa) survival model of extremity vascular injury.

BACKGROUND Despite advances in revascularization following extremity vascular injury, the relationship between time to restoration of flow and functional limb salvage is unknown. The objectives of this study are to describe a large animal survival model of hind limb ischemia/reperfusion and define neuromuscular recovery following increasing ischemic periods. METHODS Sus scrofa swine (N = 38; weight, 87 ± 6.2 kg) were randomized to iliac artery occlusion for 0 (Control), 1 (1HR), 3 (3HR), or 6 (6HR) hours, followed by vessel repair and 14 days of recovery. Additionally, one group underwent iliac artery division with no restoration of flow (Ligation), and one group underwent iliac artery exposure only without intervention (Sham). A composite physiologic measure of recovery (PMR) was generated to assess group differences over 14 days of survival. PMR included limb function (Tarlov score) and electrophysiologic measures (compound muscle action potential amplitude, sensory nerve action potential amplitude, and nerve conduction velocity). Using the PMR and extrapolating the point at which recovery following ligation crosses the slope connecting recovery after 3 and 6 hours of ischemia, an estimate of the ischemic threshold for the hind limb is made. These results were correlated with peroneus muscle and peroneal nerve histology. RESULTS Baseline physiologic characteristics were similar between groups. Neuromuscular recovery in groups with early restoration of flow (Control, 1HR, 3HR) was similar and nearly complete (92%, 98%, and 88%, respectively; P > .45). While recovery was diminished in both 6HR and Ligation, Ligation, rather than repair, exhibited greater recovery (68% vs 53%; P < .05). These relationships correlated with the pathologic grade of degeneration, necrosis, and fibrosis (P < .05). The PMR model predicts minimal and similar persistent loss of function in groups undergoing early surgical restoration of flow (Control 8%, 1HR 1%, 3HR 12%; P > .45). In contrast, the Ligation group exhibited the greatest degree of injury early in the reperfusion period, followed by more complete recovery and at a faster rate than 6HR. Extrapolating from the PMR the point at which Ligation (68% recovery) crosses the slope connecting 3 hours (84% recovery) and 6 hours (53% recovery) of ischemia estimates the ischemic threshold to be 4.7 hours. Restoration of flow at ischemic intervals exceeding this are associated with less physiologic recovery than ligation. CONCLUSION In this model, surgical and therapeutic adjuncts to restore extremity perfusion early (1-3 hours) after extremity vascular injury are most likely to provide outcomes benefit compared with delayed restoration of flow or ligation. Furthermore, the ischemic threshold of the extremity after which neuromuscular recovery is significantly diminished is less than 5 hours. Additional studies are necessary to determine the effect of other factors such as shock or therapeutic measures on this ischemic threshold.

A large animal survival model (Sus scrofa) of extremity ischemia/reperfusion and neuromuscular outcomes assessment: a pilot study.

BACKGROUND Extremity ischemia/reperfusion has been studied mostly in small-animal models with limited characterization of neuromuscular or functional outcome. The objective of this experiment was to report a large-animal survival model of extremity ischemia/reperfusion using circulating, electromyographic (EMG), gate, and histologic measures of injury and limb recovery. METHODS Sus scrofa swine (n = 6; mean, 83 kg) were randomized to iliac artery occlusion for 0 (control), 1 (1 HR), 3 (3 HR), or 6 (6 HR) hours. Restoration of flow after a standard large-vessel reconstructive technique (thrombectomy, heparin irrigation, and patch angioplasty) was performed in each of the control, 1HR, 3HR, and 6HR animals, whereas one animal had iliac artery segment excision with no restoration (NR) of axial flow. One animal had operative exposure but no intervention on the iliac artery (sham). Animals were recovered and closely monitored for 2 weeks. Indicators of ischemia/reperfusion and functional recovery, including circulating markers, EMG measures (complex motor action potential), and Tarlov gate scoring (0-4; 0, insensate/paralyzed to 4, normal posture and no gait abnormality) were measured at 24 hours and 72 hours and 7 days and 14 days. Muscle (peroneus) and nerve (peroneal) were collected during necropsy at 14 days to assess gross and histologic changes. Duplex ultrasound was performed serially during the recovery period to confirm patency of vascular reconstruction. RESULTS There were no deaths or failures of vascular reconstruction. Control had a Tarlov score of 4 and normal EMG measures at each point during recovery (same as sham). Tarlov scores at 1, 3, and 14 days recovery in each of the animals were as follows: 1HR: 3, 3, and 4; 3HR: 1, 2, and 4; 6HR: 1, 2, and 3; and NR: 1, 2, and 4. Complex motor action potential as a percentage of baseline at 1, 2, and 14 days recovery was as follows: 1HR: 56%, 55%, and 84%; 3HR: 9%, 8%, and 57%; 6HR: 5%, 5%, and 16%; and NR: 22%, 28%, and 33%. Muscle and nerve histology was the same in sham, control, and 1HR animals. Moderate degeneration and necrosis was observed in peroneus muscle of the 3HR animals. The peroneal nerve in 3HR demonstrated minimal Wallerian degeneration. Severe necrosis was present, as was minimal regeneration, and peroneal nerve demonstrated moderate Wallerian degeneration in 6HR. CONCLUSION This study reports a new large-animal survival model of extremity ischemia/reperfusion using circulating, functional, and histologic markers of neuromuscular recovery. Findings provide insight into an extremity ischemic threshold after which functional neuromuscular recovery is lost. Additional study is necessary to define this threshold and factors that may move it to a more or less favorable position in the setting of extremity injury.

CLINICAL, ELECTROPHYSIOLOGIC, AND IMAGING FEATURES OF ZOSTER-ASSOCIATED LIMB PARESIS

Introduction: Paresis is a long‐recognized complication of herpes zoster, but there has been comparatively little study of zoster‐associated limb paresis (ZALP). Methods: In this study we reviewed 49 Mayo Clinic patients with ZALP. Results: The mean age of onset was 71 years, 67% were men, and the lower limb was affected in 55%. The mean weakness score was 2.0 (0 = normal strength, 4 = plegia). Most patients developed postherpetic neuralgia (PHN, 92% at 1 month and 65% at 3 months), and the average minimum duration of weakness was 193 days. ZALP was caused by radiculopathy (37%), plexopathy (41%), mononeuropathy (14%), and radiculoplexus neuropathy (8%). MRI demonstrated nerve enlargement, T2 signal prolongation, or enhancement in a majority (64%) of affected plexi and peripheral nerves. Conclusions: ZALP is associated with considerable weakness. It typically lasts at least several months, localizes to plexus or peripheral nerve in 63%, and is associated with high rates of PHN. Muscle Nerve 50:177–185, 2014

Multifocal neuropathy associated with West Nile virus infection

A 51-year-old man developed severe, subacute onset right facial weakness and flaccid, hyporeflexic right upper limb weakness several days following West Nile virus infection. Electrophysiologic and radiographic studies confirmed severe but incomplete right facial and brachial plexus neuropathies (figure). There were no clinical or …

Zoster-associated mononeuropathies (ZAMs): a retrospective series.

Zoster‐associated limb paresis is an uncommon complication of herpes zoster (HZ) and one whose precise pathophysiologic mechanism is poorly understood. Occasionally, the paresis results from a zoster‐associated mononeuropathy (ZAM).

FOCAL AND OTHER UNUSUAL PRESENTATIONS OF FACIOSCAPULOHUMERAL MUSCULAR DYSTROPHY

Facioscapulohumeral dystrophy (FSHD) presents classically with facial and shoulder‐girdle weakness. We report focal atypical presentations of FSHD. Our aim was to identify focal/unusual phenotypes in genetically confirmed FSHD cases.

Practice improvement requires more than guidelines and quality measures

Increasing emphasis on improving health care quality has led to a variety of programs that require neurologists to be familiar with the concept of systematic quality improvement. While they vary in extent, these quality improvement programs and their attendant costs now have implications for physician payment and certification. In response to these factors, the American Academy of Neurology is establishing a clinical quality data registry. This article reviews evidence demonstrating the ability of quality improvement initiatives to improve care, the role of clinical quality data registries in the identification and mitigation of gaps in care, and the principles to be considered in development of registry-based quality improvement programs. It addresses the key question: Is the effort worthwhile?

Symptomatic left intradiploic encephalocele

A 50-year-old man developed right upper extremity weakness after a violent coughing spell. Imaging studies (figure 1, A and B) demonstrated a large fluid-filled calvarial defect containing herniated brain near the level of the motor cortex. The brain tissue which was “strangulated” by ossified dura while protruding into the calvarial defect was decompressed (figure 2), with resultant substantial progressive though incomplete clinical improvement. Intradiploic encephaloceles are rare. …