Watson, James C.

ABSTRACTIntroduction: 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

ABSTRACTIntroduction: Needle electromyography (EMG) of the diaphragm carries the potential risk of pneumothorax. Knowing the approximate depth of the diaphragm should increase the test's safety and accuracy. Methods: Distances from the skin to the diaphragm and from the outer surface of the rib to the diaphragm were measured using B mode ultrasound in 150 normal subjects. Results: When measured at the lower intercostal spaces, diaphragm depth varied between 0.78 and 4.91 cm beneath the skin surface and between 0.25 and 1.48 cm below the outer surface of the rib. Using linear regression modeling, body mass index (BMI) could be used to predict diaphragm depth from the skin to within an average of 1.15 mm. Conclusions: Diaphragm depth from the skin can vary by more than 4 cm. When image guidance is not available to enhance accuracy and safety of diaphragm EMG, it is possible to reliably predict the depth of the diaphragm based on BMI. Muscle Nerve 49: 666–668, 2014

Introduction : Real time ultrasound imaging of the diaphragm is an under‐used tool in the evaluation of patients with unexplained dyspnea or respiratory failure. Methods : We measured diaphragm thickness and the change in thickness that occurs with maximal inspiration in 150 normal subjects, with results stratified for age, gender, body mass index, and smoking history. Results : The lower limit of normal diaphragm thickness at end expiration or functional residual capacity is 0.15 cm, and an increase of at least 20% in diaphragm thickness from functional residual capacity to total lung capacity is normal. A side to side difference in thickness at end expiration of > 0.33 cm is abnormal. Diaphragm thickness and contractility are minimally affected by age, gender, body habitus, or smoking history. Conclusions : This study confirms previous findings in much smaller groups of normal controls for quantitative ultrasound of the diaphragm and provides data that can be applied widely to the general population. Muscle Nerve 47: 884–889, 2013

Introduction: Median nerve ultrasound shows increased cross‐sectional area (CSA) in carpal tunnel syndrome (CTS) and diabetic peripheral neuropathy (PN). The role of ultrasound in diagnosing CTS superimposed on diabetic PN is unknown. The objective of this study is to evaluate ultrasound for diagnosis of CTS in diabetic PN. Methods: Prospective recruitment of diabetics with electrodiagnostically proven PN, subdivided into cases (with CTS) or controls (without CTS). The gold standard for CTS was clinical diagnosis. NCS were correlated with blinded median nerve CSA ultrasound measurements. Results: Eight cases (CTS) and eight controls (no CTS) were recruited. Nerve conduction studies (NCS): Median nerve distal latencies (antidromic sensory; palmar; lumbrical motor; and lumbrical motor to ulnar interosseous difference) were significantly prolonged in CTS cases. No ultrasound measurement (distal median CSA, wrist‐forearm ratio, wrist‐forearm difference) reached significance to detect CTS. Area under the curve was greatest for lumbrical distal latency by receiver operator characteristic analysis (0.85). Conclusions: In this pilot study, NCS may be superior to ultrasound for identification of superimposed CTS in diabetic PN patients, but larger numbers are needed for confirmation. Muscle Nerve 47: 437–439, 2013

Background Congenital hyposensitivity to pain or hereditary sensory and autonomic neuropathy represents a variety of disorders characterized by decreased perception of nociception, loss of other modalities of sensation, and variable expression of autonomic dysfunction. Sensory loss, especially that of pain, is associated with self-mutilations that may require frequent operations. Little is known about the safety of anesthesia for these patients. Methods The authors performed a computerized search of the Mayo Clinic medical records database between January 1996 and November 2005 for patients with congenital hyposensitivity to pain and related disorders who underwent general anesthesia. Medical records were reviewed for demographics, anesthetic techniques and agents, use of opioids, and perioperative complications. In addition, the authors conducted a comprehensive review of the literature to summarize the current knowledge regarding anesthesia for patients with congenital hyposensitivity to pain, and compared it with the patients with hyposensitivity to pain identified at the Mayo Clinic. Results The authors identified seven patients with hereditary sensory and autonomic neuropathy II, IV, or V and undefined variants of congenital pain hyposensitivity who generated 17 anesthesia records: 12 for orthopedic operations, 3 for sural nerve biopsies, and 2 for ophthalmologic procedures. In all patients, standard doses of volatile agents were used during anesthesia. Small amounts of opioids were used during the course of eight operations. Most patients experienced mild hypothermia (lowest temperature 34.7 degrees C), and none experienced hyperthermia. All patients were hemodynamically stable during otherwise uneventful anesthesia. During recovery from anesthesia, opioids were given to only one patient, a single dose of 1 mg morphine. Even after major orthopedic operations, the patient did not require additional analgesia. Conclusions The patients with profound congenital hyposensitivity to pain underwent anesthesia without any adverse events. The authors found that despite reduced pain perception, the requirements for volatile anesthetics were within the expected range for population with normal pain perception, but they did not require opioids postoperatively. Intraoperative mild hypothermia was easily managed by adjustment of environmental temperature.