Parsonage-Turner Syndrome and Hereditary Brachial Plexus Neuropathy

Parsonage-Turner syndrome and hereditary brachial plexus neuropathy (HBPN) present with indistinguishable attacks of rapid-onset severe shoulder and arm pain, disabling weakness, and early muscle atrophy. Their combined incidence ranges from 3 to 100 in 100,000 persons per year. Dominant mutations of SEPT9 are the only known mutations responsible for HBPN. Parsonage and Turner termed the disorder "brachial neuralgic amyotrophy," highlighting neuropathic pain and muscle atrophy. Modern electrodiagnostic and imaging testing assists the diagnosis in distinction from mimicking disorders. Shoulder and upper limb nerves outside the brachial plexus are commonly affected including the phrenic nerve where diaphragm ultrasound improves diagnosis. Magnetic resonance imaging can show multifocal T2 nerve and muscle hyperintensities with nerve hourglass swellings and constrictions identifiable also by ultrasound. An inflammatory immune component is suggested by nerve biopsies and associated infectious, immunization, trauma, surgery, and childbirth triggers. High-dose pulsed steroids assist initial pain control; however, weakness and subsequent pain are not clearly responsive to steroids and instead benefit from time, physical therapy, and non-narcotic pain medications. Recurrent attacks in HBPN are common and prophylactic steroids or intravenous immunoglobulin may reduce surgical- or childbirth-induced attacks. Rehabilitation focusing on restoring functional scapular mechanics, energy conservation, contracture prevention, and pain management are critical. Lifetime residual pain and weakness are rare with most making dramatic functional recovery. Tendon transfers can be used when recovery does not occur after 18 months. Early neurolysis and nerve grafts are controversial. This review provides an update including new diagnostic tools, new associations, and new interventions crossing multiple medical disciplines.

Electrodiagnostic and ultrasound evaluation of respiratory weakness

Phrenic nerve conduction studies (NCSs) and needle electromyography (EMG) can provide important information on the underlying pathophysiology in patients presenting with unexplained shortness of breath, failure to wean from the ventilator, or consideration of phrenic nerve pacemaker implantation. However, these techniques are often technically challenging, require experience, can lack sensitivity and specificity, and, in the case of diaphragm EMG, involve some degree of risk. Diagnostic high-resolution ultrasound has been introduced in recent years as an adjuvant technique readily available at the bedside that can increase the overall sensitivity and specificity of the neurophysiologic evaluation of respiratory symptoms. Two-dimensional ultrasound in the zone of apposition can identify atrophy and evaluate contractility of the diaphragm, in addition to localizing a safe zone for needle EMG. M-mode ultrasound can identify decreased excursion or paradoxical motion of the diaphragm and can increase the reliability of phrenic NCSs. When used in combination, ultrasound, phrenic NCSs and EMG of the diaphragm can differentiate neuropathic, myopathic, and central disorders, and can offer aid in prognosis that is difficult to arrive at solely from clinical examination. This article will review techniques to successfully perform phrenic NCSs, needle EMG of the diaphragm, and ultrasound of the diaphragm. The discussion will include technical pitfalls and clinical pearls as well as future directions and clinical indications.

Neuromuscular ultrasound standardized scanning techniques and protocols: Expert panel recommendations

Neuromuscular ultrasound has become an integral part of the diagnostic workup of neuromuscular disorders at many centers. Despite its growing utility, uniform standard scanning techniques do not currently exist. Scanning approaches for similar diseases vary in the literature creating heterogeneity in the studies as reported in several meta-analysis. Moreover, neuromuscular ultrasound experts including the group in this study have different views with regards to technical aspects, scanning protocols, and the parameters that should be assessed. Establishing standardized neuromuscular scanning protocols is essential for the development of the subspeciality to ensure uniform clinical and research practices. Therefore, we aimed to recommend consensus-based standardized scanning techniques and protocols for common neuromuscular disorders using the Delphi approach. A panel of 17 experts participated in the study, which consisted of three consecutive electronic surveys. The first survey included voting on six scanning protocols addressing the general scanning technique and five common categories of suspected neuromuscular disorders. The subsequent surveys focused on refining the protocols and voting on new steps, rephrased statements, or areas of non-agreement. A high degree of consensus was achieved on the general neuromuscular ultrasound scanning technique and the scanning protocols for focal mononeuropathies, brachial plexopathies, polyneuropathies, amyotophic lateral sclerosis, and muscle diseases. In this study, a group of neuromuscular ultrasound experts developed six consensus-based neuromuscular ultrasound scanning protocols that may serve as references for clinicians and researchers. The standardized protocols could also aid in achieving high-quality uniform neuromuscular ultrasound practices.

Distal Tibial Mononeuropathy From Compression by the Posterior Tibial Artery: Clinical-Electrophysiological-Ultrasonographic Correlations

SUMMARY

The tibial nerve is bound tightly to the posterior tibial artery in the tarsal tunnel where expansion capacity is limited. Therefore, the nerve may be vulnerable to, and damaged by chronic pulsatile trauma from an atypically positioned overriding artery, labeled "punched-nerve syndrome". In this article, we present a 49-year-old woman who presented with two months of severe burning pain in the left medial ankle and sole of the foot without antecedent trauma. Neurological examination identified dysesthetic sensation to light touch in the left medial sole of the foot, and both active and passive dorsiflexion worsened the painful paresthesia. Nerve conduction studies demonstrated a reduced left medial plantar mixed nerve action potential amplitude, 50% less than the right. High-resolution ultrasound (HRUS) showed an increased left tibial nerve cross-sectional area of 26 mm2 (normal <22.3 mm2) at the level of the ankle with side-to-side difference of 6 mm2 (normal <5.7 mm2). The distal tibial nerve and its medial plantar branch were atypically positioned immediately deep to the left posterior tibial artery and abnormally flattened with focal enlargement of the nerve on longitudinal view. Dynamic analysis demonstrated the nerve being compressed with each pulsation of the tibial artery immediately above. Active dorsiflexion of the ankle narrowed the space underneath the flexor retinaculum resulting in further compression of the nerve against the artery. In conclusion, HRUS as an adjunct to electrophysiological studies identified punched-nerve arterial compression as an etiology of tarsal tunnel syndrome.

A standardized ultrasound approach in neuralgic amyotrophy

Neuralgic amyotrophy (NA), also referred to as idiopathic brachial plexitis and Parsonage-Turner syndrome, is a peripheral nerve disorder characterized by acute severe shoulder pain followed by progressive upper limb weakness and muscle atrophy. While NA is incompletely understood and often difficult to diagnose, early recognition may prevent unnecessary tests and interventions and, in some situations, allow for prompt treatment, which can potentially minimize adverse long-term sequalae. High-resolution ultrasound (HRUS) has become a valuable tool in the diagnosis and evaluation of NA. Pathologic HRUS findings can be grouped into four categories: nerve swelling, swelling with incomplete constriction, swelling with complete constriction, and fascicular entwinement, which may represent a continuum of pathologic processes. Certain ultrasound findings may help predict the likelihood of spontaneous recovery with conservative management versus the need for surgical intervention. We recommend relying heavily on history and physical examination to determine which nerves are clinically affected and should therefore be assessed by HRUS. The nerves most frequently affected by NA are the suprascapular, long thoracic, median and anterior interosseous nerve (AIN) branch, radial and posterior interosseous nerve (PIN) branch, axillary, spinal accessory, and musculocutaneous. When distal upper limb nerves are affected (AIN, PIN, superficial radial nerve), the lesion is almost always located in their respective fascicles within the parent nerve, proximal to its branching point. The purpose of this review is to describe a reproducible, standardized, ultrasonographic approach for evaluating suspected NA, and to share reliable techniques and clinical considerations when imaging commonly affected nerves.

Utility of carpal tunnel release and ulnar decompression in CMT1A and HNPP

INTRODUCTION/AIMS

Carpal and cubital tunnel syndrome (CTS, CuTS) are common among patients with hereditary neuropathy with liability to pressure-palsies (HNPP) and Charcot-Marie-Tooth-1A (CMT1A), and may impact quality of life. We aimed to evaluate the utility of nerve decompression surgeries in these patients.

METHODS

Medical records were reviewed for patients with PMP22 mutation confirmed in Mayo Clinic laboratories from January 1999 to December 2020, who had CTS and CuTS and underwent surgical decompression.

RESULTS

CTS occurred in 53.3% of HNPP and 11.5% of CMT1A, while CuTS was present in 43.3% of HNPP and 5.8% of CMT1A patients. CTS decompression occurred in 10-HNPP and 5-CMT1A patients, and CuTS decompression with/without transposition was performed in 5-HNPP and 1-CMT1A patients. In HNPP, electrodiagnostic studies identified median neuropathy at the wrist in 9/10 patients and ultrasound showed focal enlargements at carpal and cubital tunnels. In CMT1A, median and ulnar sensory responses were all absent, and the nerves were diffusely enlarged. After CTS surgery, pain, sensory loss, and strength improved in 4/5 CMT1A, and 6/10 HNPP patients. Of clinical, electrophysiologic and ultrasound findings, only activity-provoked features significantly correlated with CTS surgical benefit in HNPP patients (odds ratio=117.0:95% CI 1.94>999.99, p=0.01). One CMT1A and one HNPP patient improved with CuTS surgery while 2 HNPP patients worsened.

DISCUSSION

CTS symptom improvement post-surgery can be seen in CMT1A and (less frequent) in HNPP patients. CuTS surgery commonly worsened course in HNPP. Activity-provoked symptoms in HNPP best informed benefits from CTS surgery.

Efficacy and Tolerability of Topical Platelet Exosomes for Skin Rejuvenation: Six-Week Results

BACKGROUND

Exosomes are regenerative mediators for skin rejuvenation. In the context of aesthetic medicine, platelets are an ideal source for exosomal isolation given their role in skin healing. Human platelet extract (HPE) is an allogeneic exosome product derived from US-sourced, leukocyte-reduced apheresed platelets with consistent purity and potency.

OBJECTIVES

To better characterize the saftey and tolerability of novel human platelet extract (plated) Intensive Repair Serum, (Rion Aesthetics, Rochester, MN) and its maximal effects on skin rejuvenation at 6 weeks.

METHODS

This prospective, single-arm, non-randomized, longitudinal study investigated the safety and efficacy of human platelet extract. Structured sub-analysis evaluated multifactorial improvement in skin health following standardized skin care regimen to determine the maximal effect. Evaluation at baseline and 6-weeks included subject questionnaires and photodocumentation using VISIA-CR Generation 5 3D PRIMOS (Canfield Scientific Inc, Fairfield, NJ).

RESULTS

VISIA-CR imaging yielded quantifiable and statistically significant improvements in overall skin health (named "Skin Health Score" [SHS]), calculated by multiplying the luminosity and color evenness scores and dividing the result by wrinkle area x brown spot area x redness area). A greater score correlated to greater overall skin health and there was a statistically significant mean delta improvement 224.2 ± 112.8 (mean ± SD, p ≤ 0.0001) in SHS at 6-weeks compared to baseline. This correlated to reduction in redness, wrinkles, and melanin production across all cosmetic units (p = 0.005, p=0.0023, p ≤ 0.0001, respectively) and significant improvements in luminosity and color evenness (p ≤ 0.001).

CONCLUSIONS

A topically applied platelet-derived exosome product, human platelet extract, induced normalization to skin health at 4-6 weeks with improved various clinical measures of facial photodamage and cutaneous aging. It is safe, well-tolerated, and well-liked by subjects.

Diaphragm dysfunction in severe COVID-19 as determined by neuromuscular ultrasound

Many survivors from severe coronavirus disease 2019 (COVID-19) suffer from persistent dyspnea and fatigue long after resolution of the active infection. In a cohort of 21 consecutive severe post-COVID-19 survivors admitted to an inpatient rehabilitation hospital, 16 (76%) of them had at least one sonographic abnormality of diaphragm muscle structure or function. This corresponded to a significant reduction in diaphragm muscle contractility as represented by thickening ratio (muscle thickness at maximal inspiration/end-expiration) for the post-COVID-19 compared to non-COVID-19 cohorts. These findings may shed new light on neuromuscular respiratory dysfunction as a contributor to prolonged functional impairments after hospitalization for post-COVID-19.

Diagnostic accuracy of gray scale muscle ultrasound screening for pediatric neuromuscular disease

OBJECTIVE

Gray scale ultrasound (US) has been demonstrated to be a sensitive and specific tool in the diagnosis of pediatric neuromuscular disease (NMD). With recent advances in genetic testing, the diagnostic work up for NMD has evolved. The purpose of this study was to compare the current diagnostic value of gray scale US to previously defined sensitivities and specificities to determine when this test can add value to a patient's diagnostic workup.

METHODS

Standardized quantitative gray scale US imaging was performed on 148 pediatric patients presenting for electrodiagnostic testing to evaluate for NMD. Patients were categorized as having an NMD, a non-NMD, or as "uncertain." The US results were defined as normal, borderline or abnormal based on echointensity values. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of the test were calculated.

RESULTS

Forty-five percent of the patients had an NMD, 54% a non-NMD, and in 1% the diagnosis remained uncertain. US was abnormal in 73% of myopathies, 63% of neuromuscular junction disorders, 60% of generalized neuropathies and 58% of focal neuropathies. After excluding patients in whom muscle US was not expected to be abnormal (eg, sensory neuropathy), sensitivity was 83%, specificity 79%, PPV 75%, NPV 86%, and accuracy 81%.

CONCLUSIONS

Quantitative gray scale muscle US still has good diagnostic value as a screening tool in pediatric NMD. As with any diagnostic test, muscle US is best used in conjunction with history and physical examination to increase specificity and diagnostic yield.

AANEM - IFCN glossary of terms in neuromuscular electrodiagnostic medicine and ultrasound

Modern neuromuscular electrodiagnosis (EDX) and neuromuscular ultrasound (NMUS) require a universal language for effective communication in clinical practice and research and, in particular, for teaching young colleagues. Therefore, the AANEM and the IFCN have decided to publish a joint glossary as they feel the need for an updated terminology to support educational activities in neuromuscular EDX and NMUS in all parts of the world. In addition NMUS has been rapidly progressing over the last years and is now widely used in the diagnosis of disorders of nerve and muscle in conjunction with EDX. This glossary has been developed by experts in the field of neuromuscular EDX and NMUS on behalf of the AANEM and the IFCN and has been agreed upon by electronic communication between January and November 2019. It is based on the glossaries of the AANEM from 2015 and of the IFCN from 1999. The EDX and NMUS terms and the explanatory illustrations have been updated and supplemented where necessary. The result is a comprehensive glossary of terms covering all fields of neuromuscular EDX and NMUS. It serves as a standard reference for clinical practice, education and research worldwide.

Phrenic neuropathy water immersion dyspnea: Clinical findings and need for patient counseling

OBJECTIVE

To investigate the following among patients with phrenic neuropathy: (1) occurrences of water immersion activity-induced dyspnea; (2) clinical, electrophysiologic, sonographic, and pulmonary function test abnormalities; and (3) frequency of documented counseling regarding the risks of water immersion activities.

METHODS

We identified all patients with test-confirmed phrenic neuropathy seen from January 1, 2000, to December 31, 2018, at Mayo Clinic.

RESULTS

Of 535 patients with phrenic neuropathy, documentation of dyspnea with water activities was identified in 4% (22/535). The risks of water immersion were only documented in patients having experienced this problem. The majority had isolated phrenic neuritis or neuralgic amyotrophy syndrome (77.3%), mean age was 55 years (range 31-79), and most patients were men (81.9%). Patients had right-sided (45.5%) or bilateral (54.5%) phrenic neuropathy. None had isolated left phrenic involvement. Near-fatal drowning occurred in 18.2% (4/22), with persons needing assistance to be rescued from the water, following diving into water. Dyspnea with water immersion was the only symptom in 4.5% (1/22) and the presenting respiratory symptom in 36.4% (8/22). A range of electrophysiologic, sonographic, and pulmonary function test abnormalities including mild abnormalities were seen and not found to be significantly different from those in patients in whom water-induced dyspnea was not recorded.

CONCLUSION

Respiratory distress with water immersion activities is a serious complication of phrenic neuropathies. Physician-documented counseling is lacking. Isolated phrenic neuritis, neuralgic amyotrophy, and right-sided and bilateral phrenic involvement are most commonly implicated, but the range of severity and testing abnormalities suggest that all patients with neuralgic amyotrophy or phrenic neuropathy should be warned especially about diving into water.

Prospective evaluation of lateral femoral cutaneous nerve injuries during periacetabular osteotomy

Periacetabular osteotomies (PAOs) are used to treat acetabular dysplasia in younger patients, but are not without morbidity. Lateral femoral cutaneous nerve (LFCN) injuries are commonly associated with the approach for PAOs, but the true incidence and rate of resolution is not known. The purpose of this prospective study was to determine the incidence of LFCN injuries after PAO using an innovative nerve conduction study (NCS) and to report the patient-reported outcomes. We prospectively enrolled 23 patients (24 hips) undergoing PAOs to have pre- and post-operative NCSs at a mean of 12 weeks post-operative. Patients were followed prospectively. Patients were contacted 3 years post-operatively via phone to determine the presence and severity of symptoms. Patient-reported outcome scores were also correlated with patient symptoms. Patients (91%) reported one or more LFCN symptoms post-operatively. The most common symptoms were numbness (91%), tingling (36%), pain (18%) and burning (9%). Patients (67%) had evidence of LFCN injury based on NCSs. Symptoms (40%) resolved 4 months post-operatively. Two-thirds of patients had continued symptoms at 3 years. Only 1 patient required treatment. The incidence of LFCN injury after PAO is 90%, two-thirds of which can be identified objectively by NCS. Numbness is the most common symptom. LFCN symptoms (40%) resolve by 4 months, but two-thirds of patients may continue to have thigh numbness up to 3 years after surgery. Fortunately, symptoms are not clearly associated with outcome score and treatment for this complication is rare.

Indications for neuromuscular ultrasound: Expert opinion and review of the literature

Over the last two decades, dozens of applications have emerged for ultrasonography in neuromuscular disorders. We wanted to measure its impact on practice in laboratories where the technique is in frequent use. After identifying experts in neuromuscular ultrasound and electrodiagnosis, we assessed their use of ultrasonography for different indications and their expectations for its future evolution. We then identified the earliest papers to provide convincing evidence of the utility of ultrasound for particular indications and analyzed the relationship of their date of publication with expert usage. We found that experts use ultrasonography often for inflammatory, hereditary, traumatic, compressive and neoplastic neuropathies, and somewhat less often for neuronopathies and myopathies. Usage significantly correlated with the timing of key publications in the field. We review these findings and the extensive evidence supporting the value of neuromuscular ultrasound. Advancement of the field of clinical neurophysiology depends on widespread translation of these findings.

Phrenic neuropathy and diaphragm dysfunction in neuralgic amyotrophy

OBJECTIVE

To describe the clinical phenotype and recovery of diaphragm dysfunction caused by neuralgic amyotrophy in a large cohort of patients, to improve accurate awareness of this entity, and to encourage adoption of a standardized approach for diagnosis and treatment.

METHODS

This observational cohort study recruited adult patients with neuralgic amyotrophy and symptoms of idiopathic phrenic neuropathy from the database of the Dutch expert center for neuralgic amyotrophy and the Dutch centers for home mechanical ventilation. Demographic and clinical information on diagnosis, symptoms, and recovery was obtained from chart review. We attempted to contact all patients for a follow-up interview.

RESULTS

Phrenic neuropathy occurs in 7.6% of patients with neuralgic amyotrophy. Unilateral diaphragmatic dysfunction and bilateral diaphragmatic dysfunction are frequently symptomatic, causing exertional dyspnea, orthopnea, disturbed sleep, and excessive fatigue. Diagnostic practices varied widely and were often not optimally targeted. The majority of patients experienced at least moderate recovery within 2 years.

CONCLUSION

We recommend screening every patient with neuralgic amyotrophy for diaphragm dysfunction by asking about orthopnea and by performing upright and supine vital capacity screening and diaphragm ultrasound in cases of suspected phrenic neuropathy to optimize diagnosis and care.

Sensitivity of high-resolution ultrasonography in clinically diagnosed carpal tunnel syndrome patients with hand pain and normal nerve conduction studies

Background

Suspecting carpal tunnel syndrome (CTS) in patients with hand pain is usual. Considering the variable rate of false-negative results in nerve conduction study (NCS), as a frequent reference confirmatory standard test, we aimed to evaluate the diagnostic accuracy of neuromuscular ultrasound in patients with clinical evidence of CTS and normal NCS.

Methods

It was a diagnostic accuracy study conducted in the outpatient clinic of Rofaydeh Hospital, Tehran, Iran, between July 2012 and December 2016; it recruited clinically diagnosed CTS patients and a control group. All participants underwent comprehensive clinical examination, NCS, and high-resolution ultrasonography of the median nerve.

Results

Two hundred and fifty patients with clinical evidence of CTS met the inclusion criteria, of whom 103 (27.1%) had normal NCS and underwent an ultrasound examination. A cutoff point of 9.4 mm² (mean + 2 standard deviation) for median nerve cross-sectional area at the carpal tunnel inlet from the control group was set to detect 73% abnormality in the case group.

Conclusion

Ultrasonography had a sensitivity rate of 73% in patients with clinical CTS and negative NCS, increasing the overall diagnostic sensitivity for clinically suspected CTS in the electrodiagnostic lab setting to 92%. The study highlights the complementary role of ultraso-nography in diagnosing CTS in conjunction with NCS.

Different doses of steroid injection in elderly patients with carpal tunnel syndrome: a triple-blind, randomized, controlled trial

Background

Carpal tunnel syndrome (CTS) is commonly seen in elderly populations, in part due to increased presence of predisposing comorbidities as well as physiological changes. We aimed at comparing the effectiveness of different doses of steroid using the ultrasound-guided hydrodissection method in elderly patients with CTS.

Methods

We conducted a prospective, triple-blind, randomized, controlled trial in elderly patients with CTS. Patients were allocated to one of three groups by simplified randomization. Groups I–III received 80 mg triamcinolone (2 mL) and 1 mL of 2% lidocaine; 40 mg triamcinolone (1 mL), 1 mL of 2% lidocaine, and 1 mL normal saline; and 1 mL of 2% lidocaine and 2 mL normal saline, respectively to make up to 3 mL volume. A wrist splint was then applied for support. Outcome measures included the visual analog scale (VAS) and the Boston Carpal Tunnel Questionnaire, and median motor and sensory nerve conduction and its sonographic inlet cross-sectional area were used as objective measures. All data were recorded at baseline and 2, 12, and 24 weeks after injection. The investigators, patients, and statistician were blinded to the treatment assignment.

Results

In total, 161 patients were recruited without statistically significant demographic differences between the three groups. There were no statistically significant differences between groups in any outcome, with the exception of the median distal motor latency, which was greater in Group II at all three follow-up visits, and significant baseline VAS difference between Groups I and III.

Conclusion

Hydrodissection with lidocaine and normal saline is as effective as hydrodissection with low- and high-dose steroid medication in elderly patients with CTS in this study, but further studies with matched baseline measures and also a sham group are suggested for definitive recommendation.

Compound muscle action potential duration in critical illness neuromyopathy

INTRODUCTION

We sought to determine the specificity of compound muscle action potential (CMAP) durations and amplitudes in a large critical illness neuromyopathy (CINM) cohort relative to controls with other neuromuscular conditions.

METHODS

Fifty-eight patients with CINM who had been seen over a 17-year period were retrospectively studied. Electrodiagnostic findings of the CINM cohort were compared with patients with axonal peripheral neuropathy and myopathy due to other causes.

RESULTS

Mean CMAP durations were prolonged, and mean CMAP amplitudes were severely reduced both proximally and distally in all nerves studied in the CINM cohort relative to the control groups. The specificity of prolonged CMAP durations for CINM approached 100% if they were encountered in more than 1 nerve.

DISCUSSION

Prolonged, low-amplitude CMAPs occur more frequently and with greater severity in CINM patients than in neuromuscular controls with myopathy and axonal neuropathy and are highly specific for the diagnosis of CINM. Muscle Nerve 57: 395-400, 2018.

The utility of genetic testing in neuromuscular disease: A consensus statement from the AANEM on the clinical utility of genetic testing in diagnosis of neuromuscular disease

INTRODUCTION

The aim of this consensus statement is to provide a recommendation from AANEM experts on the clinical utility of genetic testing. It is not meant to recommend or endorse any specific genetic testing methodology or algorithm.

METHODS

The AANEM Professional Practice Committee reached a consensus based on expert opinion on the utility of genetic testing in neuromuscular diseases and made recommendations on factors that physicians and patients should consider when deciding whether to proceed with such testing.

RESULTS

Despite the costs of genetic testing, these tests can be both valuable and beneficial in the diagnosis and treatment of neuromuscular diseases in many situations.

CONCLUSIONS

The AANEM believes that performing genetic testing to arrive at a specific molecular diagnosis is a critical step in providing high-quality care to neuromuscular patients. The cost of testing should not be a deterrent, as there are important clinical, safety, psychosocial, and research benefits. Muscle Nerve 54: 1007-1009, 2016.

Reliability of a novel ultrasound system for gray-scale analysis of muscle

INTRODUCTION

Ultrasound is increasingly used as an adjunct in the diagnosis of neuromuscular disease by measuring muscle thickness and echointensity (EI). Reproducibility is limited because of variations in scanning technique and proprietary algorithms that alter EI values.

METHODS

We developed a standardized scanning protocol and a portable machine without any postimaging processing. Ten subjects underwent scanning of 6 muscles by 3 sonographers on 2 separate days. One of the sonographers repeated the protocol with 4 different machine/transducer combinations. Gray-scale values were measured from each image with the use of a region of interest (ROI) box.

RESULTS

Combined intraclass correlation coefficients were 0.92 (intra-rater), 0.88 (inter-rater), and 0.96 (inter-system). The biceps had the highest variability (coefficient of variance [COV] 12.7%), and the medial gastrocnemius had the lowest variability (COV 7.4%).

CONCLUSIONS

We demonstrate excellent reliability of a reproducible ultrasound system for gray-scale analysis of muscle that has potential applicability as a screening tool for neuromuscular disease. Muscle Nerve 56: 408-412, 2017.

Use of Angle-Independent M-Mode Sonography for Assessment of Diaphragm Displacement

OBJECTIVES

Sonographic assessment of diaphragm displacement has conventionally been conducted with M-mode sonography via an anterior subcostal approach. This method is subject to measurement errors when diaphragm displacement is not in line with the M-mode plane. We aimed to compare measurements obtained by offline angle-independent (anatomic) M-mode sonography with conventional M-mode sonography.

METHODS

Fifty healthy adults were imaged with conventional and angle-independent M-mode sonography of the bilateral hemidiaphragms at 60% maximal inspiratory capacity using an inspiratory spirometer.

RESULTS

Left hemidiaphragm displacement was successfully imaged by conventional M-mode sonography in only 70% (n = 35), as lung expansion obscured imaging, whereas 92% (n = 46) were assessable by angle-independent M-mode sonography. All right hemidiaphragm displacement could be assessed. Conventional M-mode results were higher than angle-independent M-mode results on the right (mean ± SD, 4.9 ± 1.4 versus 4.6 ± 1.2 cm, respectively; P= .003) and left (5.4 ± 1.3 versus 4.6 ± 1.0 cm; P < .001). Displacement values were different for right versus left hemidiaphragms on conventional M-mode sonography (mean difference, 0.6 ± 0.2 cm; P = .005), with only mild agreement (R² = 0.35; P < .001). There was no laterality seen in the diaphragm displacement on angle-independent M-mode sonography (mean difference, 0.1 ± 0.1 cm; P = .47), with good agreement (R² = 0.76; P < .001).

CONCLUSIONS

Angle-independent M-mode sonography leads to better visualization and assessment of the left hemidiaphragm. It records lower displacement than conventional M-mode sonography in the bilateral diaphragms, likely because of fewer orientation and translation errors. Future study is indicated to assess the clinical utility of angle-independent M-mode sonography in a population with diaphragm dysfunction.

Utility Of diaphragm ultrasound in myopathy

INTRODUCTION

Ultrasound (US) evaluation of diaphragm thickness and contractility is an effective tool in neurogenic diaphragm dysfunction. There are limited data about the value of this technique in patients with myopathy.

METHODS

We performed a retrospective chart review of cases with electromyography (EMG) -confirmed myopathy and real-time US evaluation of the diaphragm. Diaphragm thickness and thickening ratio (maximal inspiration/expiration) were measured. Demographic, imaging, pathology, and genetic data were reviewed, and the clinical diagnosis was recorded.

RESULTS

There were 19 eligible cases, of which 14 (73.7%) had abnormal US findings. Mean diaphragm thickness was 0.12 cm (SD 0.10), and the mean thickening ratio was 1.29 (SD 0.35). In all cases with abnormal US evaluation, the thickening ratio was abnormal. There were no cases with abnormal thickness alone.

CONCLUSIONS

US examination can detect diaphragm dysfunction in myopathy. It is important to measure both the baseline thickness and thickening ratio to maximize sensitivity. Muscle Nerve 55: 427-429, 2017.

Diaphragm assessment by two dimensional speckle tracking imaging in normal subjects

BACKGROUND

Conventionally, ultrasonographic assessment of diaphragm contractility has involved measuring respiratory changes in diaphragm thickness (thickening fraction) using B-mode or caudal displacement with M-mode. Two-dimensional speckle-tracking has been increasingly used to assess muscle deformation ('strain') in echocardiography. We sought to determine in a pilot study if this technology could be utilized to analyze diaphragmatic contraction.

METHODS

Fifty healthy adult volunteers with normal exercise capacity underwent ultrasound imaging. A linear array transducer was used for the assessment of diaphragm thickness, thickening fraction (TF), and strain in the right anterior axillary line at approximately the ninth intercostal space. A phased array transducer was applied subcostally for the assessment of diaphragm displacement on the right mid-clavicular line. Diaphragmatic images were recorded from the end of expiration through the end of inspiration at 60 % maximal inspiratory capacity. Diaphragm strain was analyzed off-line by speckle tracking imaging. Blinded inter- and intra-rater variability was tested in 10 cases.

RESULTS

Mean right diaphragm thickness at end-expiration (±SD: standard deviation) was 0.24 cm (±0.1), with TF of 45.1 % (±12) at 60 % peak inspiratory effort. Mean right diaphragm caudal displacement was 4.9 cm (±1). Mean right diaphragm strain was -40.3 % (±9). A moderate correlation was seen between longitudinal strain and TF (R(2) 0.44, p < 0.0001). A weak correlation was seen between strain and caudal displacement (R(2) 0.14, p < 0.01), and an even weaker correlation was seen between caudal displacement and TF (R(2) 0.1, p = 0.04). Age, gender, and body mass index were not significantly associated with right diaphragm strain or TF. Although inter- and intra-rater variability was overall good for TF, caudal displacement, and strain (inter-rater R(2); 0.8, 0.9, and 0.7, respectively [p < 0.01], intra-rater R(2); 0.9, 0.7, and 0.9, respectively [p < 0.01]), strain values did have a slightly lower inter-rater repeatability.

CONCLUSIONS

Diaphragmatic strain estimated by speckle tracking imaging was associated with conventional ultrasound measures of diaphragmatic function (TF and caudal displacement). Further clinical studies are warranted to investigate its clinical utility.

Comparison of Diaphragm Thickness Measurements Among Postures Via Ultrasound Imaging

BACKGROUND

Assessment of diaphragm contraction may be useful for identifying impairments in patients with movement dysfunction involving trunk stabilization, respiration, or both. Real-time ultrasound imaging is a readily available technology that can be used to quickly assess this aspect of diaphragm activity. Although previous studies have examined diaphragm contraction in the supine posture, a comparison of measurements between supine and upright postures has not been made.

OBJECTIVE

To examine whether diaphragm thickness measurements differ among 3 different body postures in healthy subjects.

DESIGN

Descriptive repeated measures.

SETTING

Clinical laboratory.

PATIENTS (OR PARTICIPANTS)

Twenty-four healthy subjects (12 male and 12 female) aged 22-35 years old were recruited and completed the study.

METHOD

Diaphragm thickness was assessed in via B-mode ultrasound imaging in supine, seated, and standing postures. Measurements of diaphragm thickness were taken in the zone of apposition during maximal inspiration to total lung capacity (TLC) and end-tidal expiratory lung volume (EELV). A thickness ratio (inspiration thickness/expiration thickness) was calculated to compare relative diaphragm contraction during each condition.

MAIN OUTCOME MEASUREMENTS

The primary dependent variable was diaphragm thickness (mm).

RESULTS

Average diaphragm thickness at EELV and maximum TLC were more than 20% greater in the seated and standing postures than in supine (P < .05). Moreover, the diaphragm was approximately 205% thicker at TLC than at EELV (P < .05). Relative inspiratory to expiratory thickness ratios (TLC/EELV) did not differ among postures (P = .24).

CONCLUSIONS

The diaphragm is thicker when the body is in more upright postures (standing and sitting versus supine) perhaps due to greater vertical gravitational load on the muscle and associated change in the resting length of the muscle fibers. Thus it appears that ultrasound imaging may be a sensitive tool to examine changes in diaphragm contraction during varying postural tasks.

LEVEL OF EVIDENCE

IV.

Motor Evoked Potentials

Motor evoked potentials (MEP) may be used in the diagnosis of central and peripheral neurological disorders and have become the standard of care in many operative procedures as a means to monitor the motor pathways.In the awake patient, transcranial magnetic stimulation (TMS) can be utilized with surface or subcutaneous muscle recordings to identify central conduction abnormalities, as well as assist with prognosis, in conditions such as multiple sclerosis, stroke, spinal cord injury, Parkinson’s disease, hereditary spastic paraplegia, or ALS. In the operating theater, transcranial electrical stimulation with recording from the spinal cord, root, peripheral nerve, or muscle can be used to prevent spinal cord damage, determine continuity of roots or peripheral nerves, and assist with surgical planning. MEP are significantly affected by many physiological variables and pharmacological agents. Various techniques in regards to simulation sites, stimulation parameters, and recording techniques and sites need to be modified to enhance the reproducibility and reliability of these responses.

Spinal Cord Monitoring

Intraoperative neurophysiological monitoring is a valuable tool to preserve spinal cord and spinal root integrity during surgical procedures. A monitoring plan may include somatosensory evoked potentials (SEP), motor evoked potentials (MEP), compound muscle action potentials (CMAP), and electromyography (EMG). Such monitoring is individualized depending on the preoperative clinical deficit, the structures most at risk, and the surgical and anesthesia plan. The most common use of these techniques is in primary spine disease, where the spinal cord pathways will typically be monitored with both MEP and SEP. In cervical or lumbar spine surgeries, EMG monitoring will help protect the nerve root either during decompression or during pedicle screw placement. Monitoring during spinal cord tumor resection or vascular procedures (such as aortic aneurysm repair) not only helps prevent deficit, but also allows the surgeon to proceed with confidence and not unnecessarily terminate the procedure.

Neuromuscular Ultrasound in the EMG Lab

Neuromuscular ultrasound is a portable, relatively inexpensive, widely available imaging modality that can be used to enhance the electrodiagnostic evaluation by improving its safety and accuracy, particularly in high-risk settings such as obesity, altered anatomy, anticoagulation, or other technically challenging situations. Furthermore, the emerging field of neuromuscular ultrasound has the potential to significantly increase diagnostic yield in patients presenting for electrodiagnostic testing. Focal lesions affecting nerve or muscle as well as more generalized polyneuropathy and myopathy can be diagnosed and characterized with ultrasound, including certain cases in which electrodiagnostic testing is inconclusive or negative. This chapter will review the rationale for combining electrodiagnosis with sonography in the clinical setting, including use of ultrasound to enhance safety and diagnostic yield when evaluating for neuromuscular respiratory failure.

B-mode ultrasound assessment of diaphragm structure and function in patients with COPD

BACKGROUND

Electromyographic evaluation of diaphragmatic neuromuscular disease in patients with COPD is technically difficult and potentially high risk. Defining standard values for diaphragm thickness and thickening ratio using B-mode ultrasound may provide a simpler, safer means of evaluating these patients.

METHODS

Fifty patients with a diagnosis of COPD and FEV₁ < 70% underwent B-mode ultrasound. Three images were captured both at end expiration (Tmin) and at maximal inspiration (Tmax). The thickening ratio was calculated as (Tmax/Tmin), and each set of values was averaged. Findings were compared with a database of 150 healthy control subjects.

RESULTS

There was no significant difference in diaphragm thickness or thickening ratio between sides within groups (control subjects or patients with COPD) or between groups, with the exception of the subgroup with severe air trapping (residual volume > 200%), in which the only difference was that the thickening ratio was higher on the left (P = .0045).

CONCLUSIONS

In patients with COPD presenting for evaluation of coexisting neuromuscular respiratory weakness, the same values established for healthy control subjects serve as the baseline for comparison. This knowledge expands the role of ultrasound in evaluating neuromuscular disease in patients with COPD.

Sensitivity and specificity of diagnostic ultrasound in the diagnosis of phrenic neuropathy

OBJECTIVES

To determine the sensitivity and specificity of B-mode ultrasound in the diagnosis of neuromuscular diaphragmatic dysfunction, including phrenic neuropathy.

METHODS

A prospective study of patients with dyspnea referred to the EMG laboratory over a 2-year time frame for evaluation of neuromuscular respiratory failure who were recruited consecutively and examined with ultrasound for possible diaphragm dysfunction. Sonographic outcome measures were absolute thickness of the diaphragm and degree of increased thickness with maximal inspiration. The comparison standard for diagnosis of diaphragm dysfunction was the final clinical diagnosis of clinicians blinded to the diaphragm ultrasound results, but taking into account other diagnostic workup, including chest radiographs, fluoroscopy, phrenic nerve conduction studies, diaphragm EMG, and/or pulmonary function tests.

RESULTS

Of 82 patients recruited over a 2-year period, 66 were enrolled in the study. Sixteen patients were excluded because of inconclusive or insufficient reference testing. One hemidiaphragm could not be adequately visualized; therefore, hemidiaphragm assessment was conducted in a total of 131 hemidiaphragms in 66 patients. Of the 82 abnormal hemidiaphragms, 76 had abnormal sonographic findings (atrophy or decreased contractility). Of the 49 normal hemidiaphragms, none had a false-positive ultrasound. Diaphragmatic ultrasound was 93% sensitive and 100% specific for the diagnosis of neuromuscular diaphragmatic dysfunction.

CONCLUSION

B-mode ultrasound imaging of the diaphragm is a highly sensitive and specific tool for diagnosis of neuromuscular diaphragm dysfunction.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that diaphragmatic ultrasound performed by well-trained individuals accurately identifies patients with neuromuscular diaphragmatic respiratory failure (sensitivity 93%; specificity 100%).

Diaphragm depth in normal subjects

INTRODUCTION

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.

Two-dimensional ultrasound imaging of the diaphragm: quantitative values in normal subjects

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.

Reporting the results of diagnostic neuromuscular ultrasound: an educational report

INTRODUCTION

Neuromuscular ultrasound (NMUS), an emerging diagnostic subspecialty field, has become an important extension of the electrodiagnostic examination. However, there are no formal guidelines on how to appropriately report NMUS results.

METHODS

The AANEM convened an expert panel to develop recommendations for reporting NMUS findings.

RESULTS

Providers should describe the reason for referral, the nerves or muscles studied, and normal values as well as numerical values for the results of imaging. Muscle imaging reports should also include a description of how gray-scale values were calculated. NMUS-guided needle placement reports should include a description of the length and gauge of needle, the type of probe used, and an indication of how well the patient tolerated the procedure. All reports should clearly state whether the findings were normal or abnormal and include a definitive diagnosis.

CONCLUSIONS

NMUS reports should provide comprehensive information along with a succinct conclusion, mirroring guidelines for electrodiagnostic reports.

Evidence-based guideline: neuromuscular ultrasound for the diagnosis of carpal tunnel syndrome

INTRODUCTION

The purpose of this study was to develop an evidence-based guideline for the use of neuromuscular ultrasound in the diagnosis of carpal tunnel syndrome (CTS).

METHODS

Two questions were asked: (1) What is the accuracy of median nerve cross-sectional area enlargement as measured with ultrasound for the diagnosis of CTS? (2) What added value, if any, does neuromuscular ultrasound provide over electrodiagnostic studies alone for the diagnosis of CTS? A systematic review was performed, and studies were classified according to American Academy of Neurology criteria for rating articles of diagnostic accuracy (question 1) and for screening articles (question 2).

RESULTS

Neuromuscular ultrasound measurement of median nerve cross-sectional area at the wrist is accurate and may be offered as a diagnostic test for CTS (Level A). Neuromuscular ultrasound probably adds value to electrodiagnostic studies when diagnosing CTS and should be considered in screening for structural abnormalities at the wrist in those with CTS (Level B).

The effect of obstructive sleep apnea on amputation site healing

Obstructive sleep apnea (OSA) is an independent risk for hypertension, cerebral artery stenosis, stroke and hypercoagulability.(1) Our research objective was to assess whether sleep disordered breathing affects the peripheral circulation, decreases perfusion as measured by TcPO2 and decreases the odds that a partial-foot amputation site will heal. We hypothesized that OSA would be an independent risk factor causing delayed healing of partial-foot amputations. We conducted a retrospective, observational study on a total of 307 patients who had TcPO2 measurements and underwent partial-foot amputation. Twenty-five of these patients had OSA. In our study, patients with OSA had a 3.7-fold increase in odds of healing within 3 months in comparison with patients without OSA. Of note, 16 patients (64%) with OSA were not treated with continuous positive airway pressure (CPAP) and healed within 3 months. Our results do not support our hypothesis that the presence of sleep apnea may impair healing of partial foot amputations. Further studies are needed to fully determine the effect of OSA and its treatment on TcPO2s and healing.