Palmaris brevis spasm syndrome.

Palmaris brevis spasm syndrome is a rare and benign condition of localised muscular hyperactivity. In five men, the hypothenar eminence underwent spontaneous, irregular, tonic contractions of the palmaris brevis muscle. An EMG showed spontaneous high frequency discharges of normal motor units, without evidence of neuropathy or of nerve compression. This syndrome resembles other restricted muscle hyperactivity syndromes although there are some differences. Curiously, the palmaris brevis muscle is not under voluntary control. The mechanism of the syndrome could be an ephaptic transmission possibly secondary to the transient and repeated stretching of the ulnar nerve superficial branch. In one patient a root compression was the probable origin.     

'Neurographic' palmaris brevis sign in type II degrees ulnar neuropathy at wrist.

OBJECTIVE: To investigate the source of an unusual and previously unreported volume conducted potential on motor nerve conduction studies. In a case of subacute ulnar neuropathy at wrist (UNW) selectively involving the deep motor branch, we recorded from the hypothenar eminence a large positive wave (2.5 ms-2 mV) preceding the negative takeoff of the delayed distal ulnar motor response. METHODS: We performed multiple channels motor and sensory ulnar nerve (UN) conduction studies; these included selective electrical stimulation and anaesthetic block of UN branches and also selective recording of motor responses by single fibre needles; data were confirmed by an intraoperative neurophysiological study and correlated with MRI and surgical findings. RESULTS: Detailed neurophysiological investigation demonstrated the generation of this waveform from the palmaris brevis (PB) muscle. MRI and surgical exploration documented a hypertrophy of this muscle. CONCLUSIONS: In type II degrees UNW, depolarization of a spared palmaris brevis muscle may be recorded as a positive wave preceding the delayed abductor digiti minimi motor response. SIGNIFICANCE: We underline the peculiar localizing value of this volume conducted 'meaningful artefact' in that particular setting. It actually represented an early neurographic analogue of what is known as the clinical 'Palmaris Brevis Sign' in long standing type II degrees UNW.     

Palmaris brevis spasm: an occupational syndrome

Described are five patients who developed palmaris brevis (PB) spasm syndrome following prolonged use of a computer mouse and keyboard. Electromyography showed spontaneous activity characterized by irregular discharges of single motor unit potentials and myokymia from PB muscle that did not disappear after ulnar nerve block at the wrist, suggesting a distal lesion.     

Spasm or dimpling of the hypothenar eminence

Bilateral hypothenar muscular spasm ("dimpling") was discovered in a 62 year-old man. The spasms consisted of recurrent arrhythmic contractions of the palmaris brevis muscle. E.M.G. showed no signs of denervation but the contractions could be stopped by infiltration of the ulnar nerve by xylocaine. Apparently, this syndrome has previously been reported in only two cases. Its clinical and electromyographic characteristics are similar to hemifacial spasm. Compression of the ulnar nerve after its division at the wrist could be a cause.     

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     

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     

Anomalous intrinsic hand muscle innervation in median and ulnar nerve lesions: An electrophysiological study

A case with a median nerve lesion at the wrist without thenar atrophy and another with an ulnar nerve lesion at the elbow sparing the first dorsal interosseous are reported. Simultaneous multiple channel recording demonstrated in the first case a dual innervation of the abductor pollicis brevis by median and ulnar fibers via a Martin-Gruber anastomosis. In the second case, the cross over of the median fibers innervating the first dorsal interosseous was very proximal in the antecubital fossa. Stimulation at discrete points documented that the communicating fibers from the median joined the ulnar nerve 3 cm below the medial epicondyle.

---

Sommario Vengono descritti due casi: il primo con una lesione del nervo mediano al polso senza atrofia della eminenza thenar, il secondo con una lesione del nervo ulnare al gomito che risparmiava il muscolo primo interosseo dorsale. La tecnica di registrazione simultanea con canali multipli ha consentito di dimostrare nel primo caso una innervazione duplice (mediano ed ulnare) del muscolo adbuttore breve del pollice tramite una anastomosi di Martin-Gruber. Nel secondo caso, l'incrocio verso il nervo ulnare delle fibre a partenza dal mediano e destinate ad innervare il muscolo primo interosseo dorsale, era molto prossimale nella fossa antecubitale. La stimolazione nervosa in punti discreti permetteva di dimostrare che le fibre anastomotiche provenienti dal nervo mediano si univano all'ulnare 3 cm al di sotto dell'epicondilo mediale.

     

Lifestyle risk factors for ulnar neuropathy and ulnar neuropathy‐like symptoms

Introduction: We examined whether lifestyle factors differ between patients with ulnar neuropathy confirmed by electroneurography (ENG) and those with ulnar neuropathy‐like symptoms with normal ulnar nerve ENG. Methods: Among patients examined by ENG for suspected ulnar neuropathy, we identified 546 patients with ulnar neuropathy and 633 patients with ulnar neuropathy‐like symptoms. These groups were compared with 2 separate groups of matched community referents and to each other. Questionnaire information on lifestyle was obtained. The electrophysiological severity of neuropathy was also graded. We used conditional and unconditional logistic regression. Results: Responses were obtained from 59%. Ulnar neuropathy was related to smoking, adjusted odds ratio (OR) 4.31 (95% confidence interval [CI] 2.43–7.64) for >24 pack‐years. Ulnar neuropathy‐like symptoms were related to body mass index ≥30 kg/m², OR 1.99 (95% CI 1.25–3.19). Smoking was associated with increased severity of ulnar neuropathy. Conclusions: Findings suggest that smoking specifically affects the ulnar nerve. Muscle Nerve 48 : 507–515, 2013     

Handlebar palsy--a compression syndrome of the deep terminal (motor) branch of the ulnar nerve in biking

We describe 3 patients who developed a severe palsy of the intrinsic ulnar supplied hand muscles after bicycle riding. Clinically and electrophysiologically all showed an isolated lesion of the deep terminal motor branch of the ulnar nerve leaving the hypothenar muscle and the distal sensory branch intact. This type of lesion at the canal of Guyon is quite unusual, caused in the majority of cases by chronic external pressure over the ulnar palm. In earlier reports describing this lesion in bicycle riders, most patients experienced this lesion after a long distance ride. Due to the change of riding position and shape of handlebars (horn handle) in recent years, however, even a single bicycle ride may be sufficient to cause a lesion of this ulnar branch. Especially in downhill riding, a large part of the body weight is supported by the hand on the corner of the handlebar leading to a high load at Guyon's canal. As no sensory fibres are affected, the patients are not aware of the ongoing nerve compression until a severe lesion develops. Individual adaptation of the handlebar and riding position seems to be crucial for prevention of this type of nerve lesion. Received: 7 January 2002, Received in revised form: 1 May 2002, Accepted: 7 May 2002 Correspondence to Dr. S. Beer     

Multilevel ulnar neuropathy caused by multiple intraneural hemangiomas

Intraneural hemangioma is extremely rare, and there are no reported cases that describe multilevel ulnar neuropathy caused by multiple intraneural hemangiomas in a single nerve. We report the case of a 47‐year‐old man with multilevel ulnar neuropathy caused by multiple intraneural hemangiomas in an ipsilateral ulnar nerve. Multilevel ulnar neuropathy was detected by electrodiagnosis, and intraneural hemangiomas were suggested by ultrasonographic evaluation before the operation. Careful surgical excision under an operating microscope ameliorated the patient's symptoms without recurrence. Muscle Nerve 41: 562–566, 2010     

Is medial elbow pain correlated with cubital tunnel syndrome? An electrodiagnostic study

Introduction: Medial elbow pain is often considered to be a symptom associated with ulnar neuropathy at the elbow (UNE). We examined the relationship between medial elbow pain and a positive electrodiagnostic (EDx) test result for UNE. Methods: We performed a retrospective review of 884 patients referred for EDx evaluation of UNE. Regression models were used to determine the odds ratios between clinical findings and a positive EDx result for UNE. Results: Patients reported medial elbow pain in 44.3% of cases. Clinical factors that correlated with a positive EDx study result for UNE included male gender, small and ring finger numbness, ulnar intrinsic weakness, and age. Medial elbow pain was negatively correlated with a positive EDx result. Conclusions: This study demonstrates a negative correlation between medial elbow pain and a positive EDx result for UNE. Medial elbow pain should not be considered a clear diagnostic symptom of UNE. Muscle Nerve 53: 252–254, 2016     

Ulnar neuropathy and dystonic flexion of the fourth and fifth digits: Clinical correlation in musicians

Peripheral nerve lesions are sometimes associated with focal dystonia. We diagnosed ulnar neuropathy in 28 of 73 (40%) cases of occupational cramp in musicians. Focal slowing of ulnar conduction across the elbow was identified in 15 of 19 (79%) patients using the near nerve technique and in 5 of 17 (29%) patients using surface recording. Ulnar neuropathy was present in 24 of 31 (77%) cases with flexion dystonia of the fourth and fifth digits and only 4 of the remaining 42 (10%) cases with other patterns of focal dystonia. Focal dystonia improved in 13 of 14 patients whose ulnar neuropathy improved and appeared or worsened in 2 patients following ulnar nerve injury. These data, together with our recent observation of a dystonic pattern of antagonist bursting in patients with isolated ulnar neuropathy (Muscle Nerve 1995;18:606–611), suggest that ulnar neuropathy may initiate or sustain a specific dystonia, flexion of the fourth and fifth digits, by inducing a central disorder of motor control. © 1996 John Wiley & Sons, Inc.     

The effect of temperature on nerve conduction parameters in carpal tunnel syndrome

Correction factors exist to allow for the dramatic effect that temperature has on nerve conduction study parameters. However, these are based on normal nerves in normal individuals and may not be appropriate in the diseased nerve setting. Our clinical study showed that in carpal tunnel syndrome, the median nerve reacts differently to temperature changes compared with normal ulnar controls. Furthermore, statistically significant differences exist between the rates of change with increasing temperature in motor and sensory nerves. © 1998 John Wiley & Sons, Inc. Muscle Nerve 21:1089–1091, 1998.     

Prognostic indicators from electrodiagnostic studies for ulnar neuropathy at the elbow

Introduction: We examined the prognostic value of electrodiagnostic (EDX) studies for ulnar neuropathy at the elbow (UNE). Methods: In this retrospective study, EDX results were compared with subjective recovery (resolution of symptoms) and surgery in patients diagnosed with UNE. Results: Of the 193 patients, 59 with “definite” UNE were included in the analysis. The combination of conduction block across the elbow to the first dorsal interosseous (FDI) and normal distal compound muscle action potential (CMAP) amplitude from the abductor digiti minimi (ADM) was strongly associated with recovery: 86% of these subjects achieved full subjective recovery compared to only 7% without conduction block and with an abnormal CMAP. There were no EDX predictors of surgery. Conclusion: EDX results contain useful prognostic information in UNE. Muscle Nerve, 2011     

Sonographic incidence of ulnar nerve (sub)luxation and its associated clinical and electrodiagnostic characteristics

Introduction: The aim of this study was to assess the presence of (sub)luxation of the ulnar nerve in patients with ulnar neuropathy at the elbow (UNE) compared with healthy controls (HC). We assessed its clinical patterns, electrodiagnostic, and sonographic characteristics. Methods: Using high-resolution sonography, we studied the incidence of (sub)luxation in a cohort of 342 patients and 70 HC. Results: Subluxation occurred in 14% and luxation in 6.7% of the UNE patients versus 5.7% and 5.7%, respectively, in HC (no significant differences). Pain at the elbow occurred more often in patients with (sub)luxation (P = 0.007). Electrodiagnostic and sonographic findings did not differ between patients with or without (sub)luxation. Conclusions: The incidence of ulnar nerve (sub)luxation between patients with UNE and HC does not differ. UNE patients with (sub)luxation do not have specific clinical or electrodiagnostic findings, apart from experiencing pain at the elbow more often. Muscle Nerve 47: 849–855, 2013     

Comparison of the flexed and extended elbow positions in localiziing ulnar neuropathy at the elbow

Electrophysiologic localization of ulnar neuropathy at the elbow often depends on demonstration of segmental slowing. Based on normative data obtained from 50 control subject, we compared the utility of flexed and extended elbow positions in demonstrating focal slowing at the elbow as compared to the forearm segment in patients with ulnar neuropathy. We studied 35 patients with ulnar neuropathy with definite electrophysiologic localization to the elbow segment defined by conduction block across the elbow segment or by focal slowing demonstrated either in the flexed or extended position. Applying cutoff values from the control group, all 35 patients demonstrated focal slowing at the elbow in the flexed position, whereas only 5 of 35 (14%) patients did so in the extended position. We Conclude that the flexed elbow position is more sensitive than the extended position in localizing ulnar neuropathy at the elbow and should be the preferred method when performing ulnar motor conduction studies.© 1995 John Wiley &Sons, Inc.     

Short segment sensory nerve stimulation in suspected ulnar neuropathy at the elbow: A pilot study

Introduction: Routine ulnar nerve conduction studies may be normal in very mild ulnar neuropathies at the elbow (UNE). Short segment ulnar sensory stimulation across the elbow may detect mild abnormalities in these cases. Methods: Short segment ulnar sensory nerve stimulation was performed in 20 controls and 15 patients with clinically suspected mild UNE. Greatest peak latency shift and amplitude drop between 2 adjacent stimulation sites were calculated. Results: The upper limit of normal for peak latency shift and amplitude reduction between sites was 0.7 ms and 15%, respectively. Abnormal latency shift was detected in 12 of 15 patients and focal sensory conduction block in 6 of 15 patients. In 5 of 7 patients in whom all other studies were normal, sensory inching was abnormal. Discussion: Ulnar sensory short segment stimulation may provide diagnostic confirmation and localization of the site of nerve compression in mild UNE, and may improve UNE detection when all other studies are normal. Muscle Nerve 59 :125–129, 2019     

Evaluation of patients with recurrent symptoms after ulnar nerve transposition

Focal entrapment of the ulnar nerve occurs most frequently in the region of the elbow, at the ulnar groove or beneath the humeroulnar aponeurosis. Surgical treatment commonly involves transposition of the nerve anterior to the medial epicondyle, in the antecubital fossa. Symptoms may recur after surgery, and, to assess their etiology, we studied 10 patients with recurrent ulnar symptoms after transposition. Conventional motor and sensory conduction studies were performed, as was mapping of nerve position using submaximal stimuli. In 9 of 10 patients, the ulnar nerve at the elbow was located adjacent to the medial epicondyle, rather than in the antecubital fossa. Focal slowing in the region of the elbow was noted in 8 patients, and an additional site of focal slowing was found in the forearm in 3 patients. We conclude that in patients with recurrent symptoms after ulnar nerve transposition postoperative position of the ulnar nerve may be medial, often near the medial epicondyle. This location may predispose the nerve to recurrent trauma or cause traction on the nerve at more distal locations within the forearm. The prevalence of this medial location of the ulnar nerve in asymptomatic postsurgical patients is unknown.     

A novel points system to predict the prognosis of ulnar neuropathy at the elbow

Introduction: In this study we aimed to identify prognostic factors of ulnar neuropathy at the elbow (UNE) and developed a scoring system to establish the prognosis. Methods: We collected baseline clinical, electrophysiologic, and ultrasonographic data from 2 cohorts. The outcomes for all patients were determined on follow‐up. Prognostic factors were determined using single and multiple variable analyses. A points system was developed to determine the risk for an unfavorable outcome. Results: Of the 220 patients with UNE 178 (81%) could be re‐evaluated. Four variables were retained in the prediction model for a points system. An unfavorable outcome was associated with right‐sided UNE, more severe weakness of the abductor digiti minimi (ADM), and more pronounced ulnar nerve thickening. A compound muscle action potential amplitude reduction across the elbow of ≥16% (particularly if ≥ 50%) was associated with a more favorable outcome. Conclusion: Outcome in UNE may be predicted by scoring 4 parameters. Muscle Nerve 55: 698–705, 2017     

Electrodiagnosis of ulnar neuropathy at the elbow (Une): A bayesian approach

Introduction: In ulnar neuropathy at the elbow (UNE), we determined how electrodiagnostic cutoffs [across‐elbow ulnar motor conduction velocity slowing (AECV‐slowing), drop in across‐elbow vs. forearm CV (AECV‐drop)] depend on pretest probability (PreTP). Methods: Fifty clinically defined UNE patients and 50 controls underwent ulnar conduction testing recording abductor digiti minimi (ADM) and first dorsal interosseous (FDI), stimulating wrist, below‐elbow, and 6‐, 8‐, and 10‐cm more proximally. For various PreTPs of UNE, the cutoffs required to confirm UNE (defined as posttest probability = 95%) were determined with receiver operator characteristic (ROC) curves and Bayes Theorem. Results: On ROC and Bayesian analyses, the ADM 10‐cm montage was optimal. For PreTP = 0.25, the confirmatory cutoffs were >23 m/s (AECV‐drop), and <38 m/s (AECV‐slowing); for PreTP = 0.75, they were much less conservative: >14 m/s, and <47 m/s, respectively. Conclusions: (1) In UNE, electrodiagnostic cutoffs are critically dependent on PreTP; rigid cutoffs are problematic. (2) AE distances should be standardized and at least 10 cm. Muscle Nerve 49 :337–344, 2014