A case of lateral calcaneal neuropathy: Lateral heel pain

Introduction: Although isolated injury of the sural nerve is frequently reported, entrapment involving the lateral calcaneal branch of the sural nerve (LCSN) is very rare. Methods: We report the case of a 29‐year‐old man with lateral calcaneal neuropathy of the sural nerve without any history of trauma. The diagnosis was based on clinical, electrophysiologic, and radiologic studies, including ultrasonography (US) and MRI. Results: US revealed a spindle‐shaped swelling in the posterior part of the sural nerve around the lateral malleolus. MRI showed a small lesion in the sural nerve close to the lesser saphenous vein around the level of the lateral malleolus. Two months after conservative management, the numbness and tingling in the lateral calcaneal region improved. Conclusions: Entrapment of the LCSN can arise from tight shoes. US is useful for evaluating the cutaneous nerve lesions that may be too small to detect by MRI. Muscle Nerve 54 : 801–804, 2016     

High-resolution ultrasonography in the assessment of meralgia paresthetica

Introduction: Meralgia paresthetica can be difficult to diagnose, as neurophysiological studies are often hard to interpret due to excess fatty tissue and the varying anatomy of the lateral femoral cutaneous nerve. Methods: We retrospectively analyzed the use of high‐resolution ultrasound (HRU) for confirming clinical meralgia paresthetica and compared results with nerve conduction studies. Results: In all 6 patients evaluated, HRUs showed significantly enlarged nerve diameter and in 3 enlarged cross‐sectional area, 4 had absent nerve potentials, and in 2 the potentials could not be recorded on either side. Conclusions: HRU seems promising for confirming meralgia paresthetica and can accurately localize nerve entrapment. Muscle Nerve, 2012     

Questionnaire tools for the diagnosis of carpal tunnel syndrome from the patient history

Introduction: There remains no “gold standard” for the diagnosis of carpal tunnel syndrome (CTS). Clinical diagnosis is often held to be paramount but depends on the skills of the individual practitioner. We describe two mathematical approaches to the analysis of a history obtained by questionnaire. Methods: We used two earlier instruments, a conventional logistic regression analysis, and an artificial neural network to analyze data from 5860 patients referred for diagnosis of hand symptoms. We evaluated their ability to predict whether nerve conduction studies would show evidence of CTS using receiver operating characteristic curves. Results: Both new instruments outperformed the existing tools, achieving sensitivity of 88% and specificity of 50% in predicting abnormal median nerve conduction. When combined, 96% sensitivity and 50% specificity were achieved. Conclusion: The combined instrument can be used as a preliminary screening tool for CTS, for self‐diagnosis, and as a supplement to diagnosis in primary care. Muscle Nerve, 2011     

Entrapment syndrome of multiple nerves in graft‐versus‐host disease

Introduction: Peripheral nerve entrapment syndromes are associated with hereditary neuropathy with liability to pressure palsies and a variety of rheumatic and endocrinological diseases. Methods: We report a patient with entrapment syndromes of multiple nerves associated with chronic graft‐versus‐host‐disease (GVHD) after allogeneic hematopoietic stem cell transplantation. Nerve ultrasound, histology, and ultrastructural changes were assessed. Results: The 51‐year‐old man had developed severe deep dermal sclerosis due to chronic GVHD with a progressive polyneuropathy and entrapment syndromes of multiple nerves. Pre‐stenotic enlargement was shown by nerve ultrasound. Histology demonstrated fibrosis of the epineurium with scarce infiltration of macrophages. Electron microscopy demonstrated alterations of the myelin sheaths and marked depletion of normal‐sized myelinated nerve fibers. Conclusions: In addition to polyneuropathy, chronic GVHD can be associated with peripheral nerve entrapment syndromes and should be added to the differential diagnosis of compressive neuropathies. Muscle Nerve 49 : 138–142, 2014     

Peripheral nervous system involvement in chronic spinal cord injury

Introduction: Upper motor neuron disorders are believed to leave the peripheral nervous system (PNS) intact. In this study we examined whether there is evidence of PNS involvement in spinal cord injury (SCI). Methods: Twelve subjects with chronic low cervical or thoracic SCI were included prospectively. Needle electromyography was done in 10 different muscles in each subject bilaterally. Nerve conduction studies (NCS) were conducted in the fibular, tibial, and femoral motor and fibular and sural sensory nerves. Results: Half the subjects had widespread abnormal spontaneous activity (SA), and the amount of SA correlated inversely with reflex activity and nerve length. Fibular nerve entrapment across the knee was seen in 6 subjects, and sciatic nerve entrapment was seen in 1. Apart from entrapment neuropathies, NCS changes were found predominantly in motor nerves. Conclusion: The presence of widespread electrophysiologic changes outside entrapment sites indicates that SCI has a significant impact on the entire PNS, affecting the motor part predominantly. Muscle Nerve 52 : 1016–1022, 2015     

Isolated leukemic infiltration of peripheral nervous system

Introduction: Isolated leukemic infiltration of peripheral nerves without central nervous system involvement, or isolated neuroleukemiosis, is an extremely rare complication of leukemia. Methods: We report the case of a patient with isolated neuroleukemiosis and review the pertinent literature. Results: A man with a 12‐year history of acute monoblastic leukemia presented with median mononeuropathy. Magnetic resonance imaging revealed a thickened median nerve. Nerve biopsy confirmed the diagnosis of leukemic infiltration. Clinical resolution was achieved through local radiation. Only 10 cases of isolated neuroleukemiosis have been reported. Most were in remission from leukemia. Our patient is the only one who was considered clinically cured of leukemia. Conclusions: The presumed pathophysiology of isolated neuroleukemiosis is hematogenous spread of leukemic cells into the peripheral nervous system across the blood–nerve barrier. It should be considered in the differential diagnosis in patients with leukemia who present with neuropathy, even when they are considered to be clinically cured of leukemia. Muscle Nerve 51 : 290–293, 2015     

Asymptomatic vasculitic neuropathy

Introduction: We performed a retrospective analysis of the clinical, pathological, and electrophysiological features of 21 cases of Asymptomatic vasculitic neuropathy (AsVN). Methods: Among 270 patients with biopsy‐proven vasculitic neuropathy, we identified 21 (7.8%) who had asymptomatic neuropathy. Results: Of the 21 patients with AsVN, 11 were women and 10 were men. Their mean age was 62.5 years. Referring physicians suspected systemic vasculitis on the basis of clinical and laboratory features, but none of the patients had neuropathy by examination. Screening nerve conduction studies identified neuropathy in all patients, leading us to perform a sural nerve biopsy, which confirmed the diagnosis of vasculitis. Twelve patients had active (type I), 6 had inactive (type II), and 3 had probable (type III) vasculitis. Vasculitis was primary in 10 patients and secondary in 11. Conclusions: Nerve conduction study is an important tool for identifying AsVN, a subtype of vasculitic neuropathy. Muscle Nerve 52 : 34–38, 2015     

A reliable technique for ultrasound‐guided perineural injection in ulnar neuropathy at the elbow

Introduction: Ulnar neuropathy at the elbow (UNE) is a common peripheral compression neuropathy and, in most cases, occurs at 2 sites, the retroepicondylar groove or the cubital tunnel. With regard to a potential therapeutic approach with perineural corticosteroid injection, the aim of this study was to evaluate the distribution of injection fluid applied at a standard site. Methods: We performed ultrasound‐guided (US‐guided) perineural injections to the ulnar nerve halfway between the olecranon and the medial epicondyle in 21 upper limbs from 11 non‐embalmed cadavers. In anatomic dissection we investigated the spread of injected ink. Results: Ink was successfully injected into the perineural sheath of the ulnar nerve in all 21 cases (cubital tunnel: 21 of 21; retroepicondylar groove: 19 of 21). Conclusion: US‐guided injection between the olecranon and the medial epicondyle is a feasible and safe method to reach the most common sites of ulnar nerve entrapment. Muscle Nerve 56 : 237–241, 2017     

Nerve ultrasound in diabetic polyneuropathy: Correlation with clinical characteristics and electrodiagnostic testing

Introduction: Diabetic polyneuropathy (DPN) is increasingly prevalent in the USA, but nerve ultrasound (US) findings have not been assessed systematically. Our aim was to establish the sonographic characteristics of lower extremity nerves in DPN and correlate them with electrodiagnostic (EDx) findings. Methods: Consecutive patients (n = 25) with evidence of DPN and 25 patient controls without DPN underwent blinded US imaging of the fibular and sural nerves. Nerve cross‐sectional area (CSA), diameter and echogenicity were recorded. Results: There were no differences in fibular or sural nerve CSA, diameter, or echogenicity between the 2 groups. No correlations between nerve CSA and EDx studies were found. In DPN, there were moderate inverse correlations with age (r = ?0.44 sural ankle, r = ?0.39 sural leg, r = ?0.45 fibular ankle). Conclusions: US measurements of lower extremity nerves in DPN do not differ from controls or correlate with EDx findings. Novel US techniques and/or pedal nerve US may be necessary to detect differences. Muscle Nerve 47:379‐384, 2013     

Full-length phrenic nerve transfer as the treatment for brachial plexus avulsion injury to restore wrist and finger extension

Introduction: The functional restoration of wrist and finger extension after complete brachial plexus avulsion injury remains an unsolved problem. We conducted a prospective study to elucidate a new method for resolving this injury. Methods: Six patients with complete brachial plexus avulsion injury underwent a new surgical procedure in which the full‐length phrenic nerve was transferred to the medial portion of the radial nerve at the level of the latissimus dorsi insertion via endoscopic thoracic surgery. Results: In 5 patients, extensor carpi ulnaris and extensor carpi radialis strength recovered to Medical Research Council grade ≥M3, and in 4 patients extensor digitorum strength recovered to ≥M3. Conclusions: Neurotization of phrenic nerve to the medial portion of the radial nerve at the level of latissimus dorsi insertion is a feasible means of restoring wrist and finger extension in cases of complete brachial plexus avulsion injury. Muscle Nerve 45: 39–42, 2012     

Giant nerves in chronic inflammatory polyradiculoneuropathy

Introduction: Nerve enlargement (NE) is described in inflammatory and inherited neuropathies. It is commonly multifocal and moderate in the former and homogeneous and generalized in the latter. We describe 4 cases of massive NE in inflammatory neuropathies. Methods: Patients presented with symptoms of polyneuropathy that progressed over months to years. Nerve conduction studies (NCS), laboratory analysis, nerve MRI, and nerve ultrasound were performed. Results: NCS revealed demyelinating neuropathy in all with multifocal conduction blocks or increased terminal latency indices. MRI/ultrasound revealed extensive NE in the roots and nerves. Detailed diagnostics including biopsies, positron emission tomography‐computed tomography, and genetic testing revealed no other pathology. Chronic inflammatory demyelinating polyneuropathy variants were diagnosed in all, and immunotherapies were successfully initiated. Conclusions: MRI and ultrasound contributed to diagnosis and therapy. All patients had giant NE in common, which strongly suggested inherited neuropathy. However, the final diagnosis was inflammatory neuropathy. Impressive NE can occur in immune‐mediated neuropathies and should be carefully differentiated from inherited neuropathies. Muscle Nerve 55 : 285–289, 2017     

Median nerve ultrasound in diabetic peripheral neuropathy with and without carpal tunnel syndrome

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     

Ultrasound of peripheral nerves in neuralgic amyotrophy

Introduction: Neuralgic amyotrophy (NA) can often be difficult to diagnose. Nerve ultrasound (US) is potentially useful, but it is operator-dependent, especially for small nerves. Methods: Fifty-one consecutive patients with NA (mean duration 16 months) and 50 control subjects underwent US of the brachial plexus and major nerves of the upper extremity at predefined sites. We compared cross-sectional areas (CSAs) of affected and unaffected sides with controls and sides within patients. Results: The median nerve and radial nerve at the level of the upper arm were enlarged on the affected sides compared with controls and the unaffected sides of patients. Enlargement was most pronounced for affected sides vs. controls (median 44%, radial 67%). Discussion: NA patients showed increased CSAs, especially in the major nerves of the upper limb, even after longer disease duration. This could make US a useful adjunct in diagnosing NA. Muscle Nerve 59 :55–59, 2019     

Sonographic features in hereditary neuropathy with liability to pressure palsies

Introduction: Diagnostic nerve ultrasound is becoming more commonly used by both radiologists and clinicians. The features of different neuromuscular conditions must be described to broaden our understanding and ability to interpret findings. Methods: Our study examines the sonographic features of 7 subjects with hereditary neuropathy with liability to pressure palsies (HNPP) in comparison to 32 controls by measuring the nerve cross‐sectional area (CSA) of the median, ulnar and tibial nerves. Results: Significant differences (P < 0.05) in nerve size were found. The HNPP group had a larger CSA for the median nerve at the wrist and ulnar nerve at the elbow (entrapment sites), but not the forearms. The tibial nerve at the ankle was also larger in the HNPP group, suggesting possible concomitant tibial neuropathy at the ankle. Conclusion: These results will help shape imaging protocols to better detect conditions with non‐uniform nerve enlargements. Muscle Nerve 2011     

Ultrasound assessment of the sural nerve in patients with neuropathic pain after ankle surgery

Introduction: The sural nerve may be damaged after ankle injury. The aim of our study was to determine the diagnostic utility of high‐resolution sonography in patients with ankle fractures treated by open reduction and internal fixation in whom there was a clinical suspicion of sural neuropathy. Methods: We examined the ultrasound (US) characteristics of patients with and without postsurgical sural neuropathic pain and healthy volunteers. Cross‐sectional area (CSA), echogenicity, and vascularization of the sural nerves were recorded. Results: Fourteen participants and all sural nerves were identified. CSA (P < 0.001) and vascularization (P = 0.002) were increased in symptomatic patients when compared with asymptomatic patients and healthy volunteers. There were no significant differences in nerve echogenicity (P = 0.983). Discussion: US may be a valuable tool for evaluating clinically suspected sural nerve damage after ankle stabilization surgery. Sural nerve abnormalities are seen in patients with postsurgical neuropathic pain. Muscle Nerve 57 : 407–413, 2018     

Chronic nerve compression alters Schwann cell myelin architecture in a murine model

Introduction: Myelinating Schwann cells compartmentalize their outermost layer to form actin‐rich channels known as Cajal bands. Herein we investigate changes in Schwann cell architecture and cytoplasmic morphology in a novel mouse model of carpal tunnel syndrome. Methods: Chronic nerve compression (CNC) injury was created in wild‐type and slow‐Wallerian degeneration (Wld^S) mice. Over 12 weeks, nerves were electrodiagnostically assessed, and Schwann cell morphology was thoroughly evaluated. Results: A decline in nerve conduction velocity and increase in g‐ratio is observed without early axonal damage. Schwann cells display shortened internodal lengths and severely disrupted Cajal bands. Quite surprisingly, the latter is reconstituted without improvements to nerve conduction velocity. Conclusions: Chronic entrapment injuries like carpal tunnel syndrome are primarily mediated by the Schwann cell response, where decreases in internodal length and myelin thickness disrupt the efficiency of impulse propagation. Restitution of Cajal bands is not sufficient for remyelination after CNC injury. Muscle Nerve, 2012     

Prognostic factors in carpal tunnel syndrome treated with a corticosteroid injection

Introduction: Symptoms often return in patients with carpal tunnel syndrome (CTS) who are treated with a local corticosteroid injection. We aimed to determine prognostic factors for a successful long‐term outcome. Methods: We prospectively followed 113 patients who received an injection for CTS. Clinical, electrophysiological, and ultrasonographic tests were done at baseline, and clinical outcome was evaluated after 1, 3, 6, and 12 months. The primary outcome measure for success was no need for additional treatment (e.g., surgery) within 1 year. Results: After 1 month, most patients improved, but after 12 months 67.4% had surgery. Patients with a successful outcome had a lower median nerve ultrasonographic cross‐sectional area (CSA) at the pisiform bone, a lower swelling ratio, and a lower symptom severity score. Conclusions: Less pronounced median nerve swelling measured by ultrasonography may indicate a less severe stage of CTS, which is more likely to respond to treatment with a corticosteroid injection. Muscle Nerve, 2011     

Sonographic measurements of longitudinal median nerve sliding in patients following nerve repair

Nerve sliding may be restricted following nerve repair. This could result in increased tension across the repair site and lead to poor functional recovery of the nerve. Ultrasound was used to examine longitudinal median nerve sliding in 10 patients who had previously undergone nerve repair surgery following complete division of the median nerve. The median longitudinal movement in the forearm in response to metacarpophalangeal (MCP) joint movements was 2.15 mm on the injured side, compared with 2.54 mm on the uninjured side, a difference that was significant. There was a significant reduction in nerve sliding following repair (median = 8%, range ?8% to 54%; P = 0.02), which correlated with time from injury to surgery (rho = 0.87; P = 0.001). These results indicate that ultrasound can be used as an adjunct assessment tool to monitor both morphology and sliding of the nerve through the repair site. It may have future application in the investigation of patients with persisting functional impairment following primary nerve repair. Muscle Nerve, 2009     

Relating applied strain to the type and severity of structural damage in the rat median nerve using second harmonic generation microscopy

Introduction: The objective of this study was to determine if the presence or absence of a palmaris longis tendon influenced the function of the median nerve across the wrist. The primary hypothesis was that the presence of a palmaris longus tendon would be associated with more median nerve entrapment at the wrist. Methods: This was a cross‐sectional study. Subjects were recruited at a screening of dental professionals. The median and ulnar sensory nerve latencies across the wrist (relative prolongation of the median compared with the ulnar) and the presence or absence of the palmaris longus tendon were the primary outcome measures. Results: A total of 462 subjects were recruited into the study of which 16.2% lacked a palmaris longus tendon. There was no difference in the median nerve function or the percentage with a 0.5 ms prolongation of the median sensory latency when comparing subjects with and without a palmaris longus tendon. Conclusions: The presence of a palmaris longus tendon does not influence the median nerve function across the wrist. Muscle Nerve 45: 895–896, 2012     

Calcitonin pump improves nerve regeneration after transection injury and repair

Introduction: After nerve injury, excessive calcium impedes nerve regeneration. We previously showed that calcitonin improved nerve regeneration in crush injury. We aimed to validate the direct effect of calcitonin on transected and repaired nerve. Methods: Two rat groups (n = 8) underwent sciatic nerve transection followed by direct repair. In the calcitonin group, a calcitonin‐filled mini‐osmotic pump was implanted subcutaneously, with a catheter parallel to the repaired nerve. The control group underwent repair only, without a pump. Evaluation and comparison between the groups included: (1) compound muscle action potential recording of the extensor digitorum longus (EDL) muscle; (2) tetanic muscle force test of EDL; (3) nerve calcium concentration; and (4) nerve fiber count and calcified spot count. Results: The calcitonin pump group showed superior recovery. Conclusions: Calcitonin affects injured and repaired peripheral nerve directly. The calcitonin‐filled mini‐osmotic pump improved nerve functional recovery by accelerating calcium absorption from the repaired nerve. This finding has potential clinical applications. Muscle Nerve 51 : 229–234, 2015