Accessory Flexor Digitorum Longus Presenting as Tarsal Tunnel Syndrome: A Case Series.

ABSTRACT: Tarsal tunnel syndrome (TTS) typically occurs from extrinsic or intrinsic sources of compression on the tibial nerve. We present 3 cases of patients, all of whom have a prolonged time to diagnosis after evaluation with multiple specialties, with foot pain ultimately secondary to an accessory flexor digitorum longus muscle causing TTS. The literature describing the association between TTS and accessory musculature has been limited to single case reports and frequently demonstrate abnormal electrodiagnostic testing. In our series, 2 cases had normal electrodiagnostic findings despite magnetic resonance imaging (MRI) that later revealed TTS and improvement with eventual resection. A normal electromyogram should not preclude the diagnosis of TTS and MRI of the ankle; it should be considered a useful diagnostic tool when examining atypical foot pain.

Can Carpal Tunnel Syndrome be Appropriately Diagnosed in a Cold Hand?

INTRODUCTION: The diagnosis of carpal tunnel syndrome (CTS) with nerve conduction studies traditionally involves warming the hand to avoid misleading prolongation of distal latency (DL). Comparing the median nerve DL to the ulnar and radial nerves using the combined sensory index (CSI) has been reported to improve the accuracy of CTS diagnosis. During this study, the authors examined the effect of hand temperature on the CSI and diagnosis of CTS. METHODS: The authors conducted a prospective, controlled, cohort study with 20 asymptomatic control patients and 21 symptomatic patients with confirmed CTS. Symptomatic patients underwent nerve conduction studies with the CSI calculated under both cold and warm conditions. RESULTS: Control subjects with warm hands had an average CSI of 0.0 milliseconds (ms), and -0.3ms with cold hands. CTS subjects with warm hands had an average CSI of 3.2ms, and 3.7ms with cold hands. Although hand temperature was shown to slow sample latencies, differences calculated with the CSI did not misclassify any of the 41 sample subjects. CONCLUSIONS: During this study, cold temperature did not result in misclassification of either control patients or CTS patients when CSI was diagnostically used. Based on these results, peak latency comparisons in cold hands can be considered as diagnostically reliable as under standard hand temperature ranges for the diagnosis of CTS, with caution warranted in borderline cases. This diagnostic technique can save time for the patient, physician, and care team without compromising quality of care. Future larger sample blinded studies at multiple electrodiagnostic sites are indicated.

Predictive Outcome Modeling of Preoperative Clinical Symptoms and Electrodiagnostic Data in Tarsal Tunnel Surgery.

Background The relationship between tarsal tunnel syndrome (TTS), electrodiagnostic (Edx) findings, and surgical outcome is unknown. Analysis of TTS surgical release outcome patient satisfaction and comparison to Edx nerve conduction studies (NCSs) is important to improve outcome prediction when deciding who would benefit from TTS release. Methods Retrospective study of 90 patients over 7 years that had tarsal tunnel (TT) release surgery with outcome rating and preoperative tibial NCS. Overall, 64 patients met study inclusion criteria with enough NCS data to be classified into one of the following three groups: (1) probable TTS, (2) peripheral polyneuropathy, or (3) normal. Most patients had preoperative clinical provocative testing including diagnostic tibial nerve injection, tibial Phalen's sign, and/or Tinel's sign and complaints of plantar tibial neuropathic symptoms. Outcome measure was percentage of patient improvement report at surgical follow-up visit. Results Patient-reported improvement was 92% in the probable TTS group ( n = 41) and 77% of the non-TTS group ( n = 23). Multivariate modeling revealed that three out of eight variables predicted improvement from surgical release, NCS consistent with TTS ( p = 0.04), neuropathic symptoms ( p = 0.045), and absent Phalen's test ( p = 0.001). The R 2 was 0.21 which is a robust result for this outcome measurement process. Conclusion The best predictors of improvement in patients with TTS release were found in patients that had preoperative Edx evidence of tibial neuropathy in the TT and tibial nerve plantar symptoms. Determining what factors predict surgical outcome will require prospective evaluation and evaluation of patients with other nonsurgical modalities.

An Additional Electrodiagnostic Tool for Ulnar Neuropathy: Mixed across the Elbow.

Background Diagnosing ulnar neuropathy at the elbow (UNE) remains challenging despite guidelines from national organizations. Motor testing of hand intrinsic muscles remains a common diagnostic method fraught with challenges. Objective The aim of the study is to demonstrate utility of an uncommon nerve conduction study (NCS), mixed across the elbow, when diagnosing UNE. Methods Retrospective analysis of 135 patients, referred to an outpatient University-based electrodiagnostic laboratory with suspected UNE between January 2013 and June 2019 who had motor to abductor digiti minimi (ADM), motor to first dorsal interosseus (FDI), and mixed across the elbow NCS completed. To perform the mixed across the elbow NCS, the active bar electrode was placed 10-cm proximal to the medial epicondyle between the biceps and triceps muscle bellies. The median nerve was stimulated at the wrist followed by stimulation of the ulnar nerve at the ulnar styloid. The difference between peak latencies, labeled the ulnar-median mixed latency difference (U-MLD), was used to evaluate for correlation between the nerve conduction velocities (NCV) of ADM and FDI. Results Pearson r -values = -0.479 and -0.543 ( p < 0.00001) when comparing U-MLD to ADM and FDI NCV across the elbow, respectively. The negative r -value describes the inverse relationship between ulnar velocity across the elbow and increasing U-MLD. Conclusion Mixed across the elbow has moderate-strong correlation with ADM and FDI NCV across the elbow. All three tests measure ulnar nerve function slightly differently. Without further prospective data, the most accurate test remains unclear. The authors propose some combination of the three tests may be most beneficial when diagnosing UNE.

Frequency of Electrodiagnostically Measurable Berrettini Anastomosis.

PURPOSE: Ulnar sensory palmar crossover to digit three (D3), the Berrettini anastomosis, is measurable in routine electrodiagnostic nerve conduction studies. The crossover is reported as occurring in 60% of anatomic dissections, but the frequency of measurable ulnar crossover to D3 and its potential as a nerve conduction pitfall is not established. The purpose of this article was to present descriptive statistics regarding the frequency of measurable Berrettini anastomosis in nerve conduction studies. METHODS: A retrospective chart review and data analysis was completed on 248 patients representing 411 extremities with a main outcome measure of ulnar sensory stimulated nerve conduction simultaneous waveform recording on D3 and digit four (D4). Consistent electrodiagnostic technique with waveform recording data analysis in a private practice and independent university waveform verification was completed on sequential patients referred for upper extremity electrodiagnostic testing. RESULTS: Measurable ulnar stimulated D3 sensory nerve action potentials were demonstrated in 34% of patients with amplitudes of 27%, the simultaneously recorded corresponding ulnar D4 amplitudes representing electrophysiological evidence of ulnar sensory crossover. CONCLUSIONS: The Berrettini anastomosis can frequently be seen as a small amplitude sensory nerve action potential response, but at times can be observed with an amplitude greater than 10 µV. It is possible that patients with an absent or significantly delayed median nerve response may have simultaneous inadvertent spread of stimulus to ulnar axons measurable on D3 that may be interpreted as a falsely normal response. All electromyographers need to be aware of this potential pitfall.

Incidence of injury and illness during the 2013 world dwarf games.

BACKGROUND: Dwarfism, or skeletal dysplasia, is a term used to describe short stature. Injuries to athletes with disabilities and medical co-morbidities, such as those present in the dwarf population, can have significant consequences on functionality. The main objectives of this retrospective descriptive study were to 1) evaluate the safety of athletic participation among athletes with skeletal dysplasia, 2) investigate the incidence and characteristics of injuries and illnesses among athletes with skeletal dysplasia during the 2013 World Dwarf Games held on the campus of Michigan State University, 3) describe details and overview of the World Dwarf Games, and 4) identify possible safety and rule issues to improve safety at future World Dwarf Games. METHODS: This was a retrospective review of case series interactions between dwarf athletes and the medical staff present at the 2013 World Dwarf games from August 3-10, 2013. Injury incidence rates were calculated by dividing the number of incident injuries by total athlete-competitions. Epidemiologic incidence proportion calculations were used to measure average injury risks. RESULTS: A total of 24 competition related injuries were recorded among the 409 athletes. Only 1 illness (otitis media) was reported during the week of games. The overall injury incidence rate was found to be 0.78 injuries per 100 athlete-competitions. The overall epidemiologic incidence proportion was 5.9% (7.2% for males, 3.0% for females). The most common type of injury was a muscle/tendon strain (41.7% of all injuries). The sport with the most reported injuries was soccer with 4.63 injuries per 100 athlete-competitions. CONCLUSIONS: Based on the data collected, it does appear that athletes with skeletal dysplasia can safely participate in the events offered during the World Dwarf Games. None of the reported injuries or illnesses precluded the athletes from returning to play. Data collected at future competitions will help identify trends, which may lead to rule changes to improve safety and a decrease in injuries. Adding a designated spectator area for athletes as well as modifying rules to prevent excessive physical contact in soccer and basketball competitions may reduce the incidence of injury.

Comparison of four different nerve conduction techniques of the superficial fibular sensory nerve.

INTRODUCTION: There are many different nerve conduction study (NCS) techniques to study the superficial fibular sensory nerve (SFSN). We present reference distal latency values and comparative data regarding 4 different NCS for the SFSN. METHODS: Four different NCS techniques, Spartan technique, Izzo techniques (medial and intermediate dorsal cutaneous branches), and Daube technique, were performed on (114) healthy volunteers. A total of 108 subjects with 164 legs were included. RESULTS: The mean latency of the Spartan technique was longest (3.9 ± 0.3 ms) while the Daube technique was the shortest (3.6 ± 0.7 ms). The mean amplitude of the Daube technique displayed the highest (15.2 ± 8.2 µV) with the Spartan technique having the lowest (8.7 ± 4.2 µV). Among the absent sensory nerve action potentials (SNAPs), the Spartan technique was absent only twice (1.2%) and the Izzo Medial technique was absent more than the other techniques (2.9%). CONCLUSIONS: All 4 techniques were reliable methods for obtaining the superficial fibular nerve SNAP, present in 95% of individuals. Muscle Nerve 56: 458-462, 2017.

Motor unit number estimation: a technology and literature review.

INTRODUCTION: Numerous methods for motor unit number estimation (MUNE) have been developed. The objective of this article is to summarize and compare the major methods and the available data regarding their reproducibility, validity, application, refinement, and utility. METHODS: Using specified search criteria, a systematic review of the literature was performed. Reproducibility, normative data, application to specific diseases and conditions, technical refinements, and practicality were compiled into a comprehensive database and analyzed. RESULTS: The most commonly reported MUNE methods are the incremental, multiple-point stimulation, spike-triggered averaging, and statistical methods. All have established normative data sets and high reproducibility. MUNE provides quantitative assessments of motor neuron loss and has been applied successfully to the study of many clinical conditions, including amyotrophic lateral sclerosis and normal aging. CONCLUSIONS: MUNE is an important research technique in human subjects, providing important data regarding motor unit populations and motor unit loss over time.

Undershooting of a neutral reference position by asymptomatic subjects after cervical motion in the sagittal plane.

OBJECTIVE: The objective of this study was to determine if blindfolded, asymptomatic subjects undershoot or overshoot a self-selected neutral reference position (NRP) when performing a full-cycle, head repositioning accuracy test in the sagittal plane. METHODS: An asymptomatic group of subjects, consisting of 7 men and 5 women with no history of head and neck pain, were recruited for the study. Subjects, performing a full-cycle series of head/neck movements in the sagittal plane, attempted to return to a self-selected NRP, defined at the beginning of the movement sequence, without benefit of visual clues. Data were collected for each subject, and repositioning errors were calculated. The sign of the error was used to determine if undershooting or overshooting of the NRP had occurred. RESULTS: Subjects undershot a self-selected NRP at statistically significant levels (P < .01) when performing the head repositioning accuracy test while blindfolded. Subjects undershot the NRP 83% of the time when moving from flexion to the NRP and undershot the NRP 92% of the time when moving from extension to the NRP. A Fisher exact test showed no significant difference between the number of times subjects undershot the NRP when moving from either flexion to the NRP or from extension to the NRP. To our knowledge, neither undershooting nor overshooting of an NRP has previously been reported for asymptomatic subjects at statistically significant levels. CONCLUSION: Knowing that asymptomatic subjects undershoot an NRP may help to direct treatment and rehabilitation of patients who have experienced whiplash-type injuries and are shown to overshoot the NRP when performing the same test.

A standardized protocol for needle placement in suboccipital muscles.

The objective of this study was to assess the safety and accuracy of using common anatomic landmarks to guide the placement of needle electrodes into suboccipital muscles. Atrophic changes in suboccipital muscles have been reported in some patients who have tension-type headaches, and in some patients who have headaches resulting from whiplash-type injuries. These atrophic changes most likely result from disuse or denervation. Needle electromyography is a definitive technique for determining the cause of muscle atrophy, but requires that needle electrodes be inserted into the muscle. Suboccipital muscles present a challenge to the electromyographer in that they are physically small and are located in close proximity to one another. Atrophied muscles with fatty replacement and the presence of critical structures such as the vertebral artery further complicate the procedure. Using a standardized protocol, three investigators attempted blind needle insertions into each of the suboccipital muscles of eight embalmed cadavers. A dissector then assessed targeted muscle penetrations, final resting positions of the wires, and their proximity to critical structures. Eighty-one percent of 181 attempted insertions penetrated the targeted muscles: 83% for the rectus capitis posterior minor, 83% for the rectus capitis posterior major, 94% for the obliquus capitis superior, and 63% for the obliquus capitis inferior muscles, respectively. It was concluded that readily palpable external landmarks can be used to safely and reliably guide the insertion of needle electrodes into three of the four pairs of suboccipital muscles.

Unusual presentation of hereditary neuropathy with liability to pressure palsies.

BACKGROUND: Hereditary neuropathy with liability to pressure palsies (HNPP) is an autosomal-dominant painless peripheral neuropathy characterized by episodes of repeated focal pressure neuropathies at sites of entrapment/compression, with a considerable variability in the clinical course. Electrodiagnostic and genetic testing are important in the diagnostic evaluation of these patients. CASE PRESENTATION: We report an unusual HNPP phenotype, five compression neuropathies in four nerves in a patient with bilateral hand numbness. A 42-year-old female, presented with acute bilateral paresthesias and weakness in her hands after starting yoga exercises requiring hyperextension of her hands at the wrists. Her presentation was complicated by: a) a remote history of acute onset foot drop and subsequent improvement, b) previous diagnoses of demyelinating peripheral neuropathy, possibly Charcot-Marie-Tooth disease, and c) exposure to leprosy. Electrodiagnostic testing showed 5 separate compression neuropathies in 4 nerves including: severe left and right ulnar neuropathies at the wrist, left and right median neuropathies at the wrist and left ulnar neuropathy at the elbow. There was a mild generalized, primarily demyelinating, peripheral polyneuropathy. Based on the clinical suspicion and electrodiagnostic findings, consistent with profound demyelination in areas of compression, genetic analysis was done which identified a deletion of the PMP-22 gene consistent with HNPP. CONCLUSION: HNPP can present with unusual phenotypes, such as 5 separate mononeuropathies, bilateral ulnar and median neuropathies at the wrists and ulnar neuropathy at the elbow with mild peripheral demyelinating polyneuropathy associated with the PMP-22 gene deletion.

Musculoskeletal disorders in referrals for suspected lumbosacral radiculopathy.

OBJECTIVE: An electrodiagnostic evaluation is often requested for patients with suspected lumbosacral radiculopathy. Although musculoskeletal disorders can produce lower-limb symptoms, their prevalence in this referral population is unknown. The purpose of this study was to determine the prevalence of common lower-limb musculoskeletal disorders in patients referred for lower-limb electrodiagnosis and determine whether these findings predict study outcome. DESIGN: Subjects undergoing an electrodiagnostic study for lower-limb symptoms and suspected lumbosacral radiculopathy constituted the sample. A standardized clinical and electrodiagnostic evaluation was performed for all patients. RESULTS: There were 170 subjects included. The mean age was 52 (SD = 17), and 45% were males. The total prevalence of musculoskeletal disorders in the sample was 32%. The prevalence in those with a normal study was 55% as compared with 21% in those with lumbosacral radiculopathy (P < 0.0001). CONCLUSIONS: Musculoskeletal disorders are common in patients suspected of having lumbosacral radiculopathy. The high prevalence among both patients with normal studies and those with radiculopathy and other disorders limits the usefulness of this information in predicting study outcome. In particular, it is common for patients to have two or more problems and the presence of a musculoskeletal disorder should not preclude such testing.

Musculoskeletal disorders in referrals for suspected cervical radiculopathy.

OBJECTIVES: To determine (1) the prevalence of selected common musculoskeletal disorders in patients referred for electrodiagnosis when cervical radiculopathy is suspected and (2) whether these findings predict electrodiagnostic study outcome. DESIGN: Prospective study. SETTING: Electrodiagnostic laboratories in departments of physical medicine and rehabilitation at 5 participating institutions. PARTICIPANTS: A total of 191 subjects undergoing electrodiagnostic evaluations for upper-limb symptoms when cervical radiculopathy was suspected. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Prevalence of certain musculoskeletal disorders (myofascial pain, shoulder impingement, lateral epicondylitis, de Quervain's tenosynovitis) and outcomes of electrodiagnostic testing (normal study, cervical radiculopathy, or another electrodiagnostically confirmed diagnosis). RESULTS: The total prevalence of musculoskeletal disorders was 42%. The prevalence in those with a normal study was 69%, compared with 29% in those with cervical radiculopathy (P<.001) and 45% in those with another diagnosis (P=.02). CONCLUSIONS: Musculoskeletal disorders are common in patients with suspected cervical radiculopathy. Although the presence of certain musculoskeletal disorders makes having a normal electrodiagnostic evaluation significantly more likely, the high prevalence among both patients with normal studies and those with radiculopathy and other disorders limits the usefulness of this information in precisely predicting study outcome. The presence of musculoskeletal disorders should not preclude electrodiagnostic testing when otherwise indicated.

The prevalence of fibromyalgia in collegiate athletes.

BACKGROUND: : The prevalence of fibromyalgia in the general population is reported in numbers that range between 0.5% and 10%, with considerable variability in the populations studied and criteria for diagnosis used. The prevalence in competitive young adult athletes is unknown, but we expect it to be less than the general population. OBJECTIVES: : The objective of this study was to determine the prevalence of fibromyalgia in college student athletes. METHODS: : We conducted a prospective, cross-section cohort evaluation of 641 athletes using the 1990 American College of Rheumatology (ACR) criteria. Volunteer college student athletes were evaluated with a questionnaire and physical examination at preparticipation physical examinations from 1993 to 1999. RESULTS: : Of the 641 athletes examined, we found only one who met the ACR criteria for a diagnosis of fibromyalgia. LIMITATIONS: : There were a limited number of athletes involved, there was no age- or activity-matched control group, and there were no other demographic information or associated symptoms collected. CONCLUSIONS: : The prevalence for fibromyalgia in this population was found to be 0.16%, which is lower than the prevalence found in studies describing other populations. The protective effects of this population are unclear but could be related to age, fitness level, self-selection, and/or other factors.

Thoracic radiculopathy.

Thoracic radiculopathy represents an uncommon spinal disorder that is frequently overlooked in the evaluation of spinal pain syndromes. Degenerative disc disease and diabetes mellitus may frequently cause radiculopathy at the thoracic level. Electromyography and magnetic resonance imaging are useful in the evaluation of radiculopathy and thoracic spinal pain syndromes. Percutaneous vertebroplasty is a procedure that may be used in the treatment of thoracic spinal pain syndromes. Surgical intervention for thoracic radiculopathy usually is reserved for patients with progressive myelopathy and neurologic compromise.