Electrodiagnostic testing in lumbosacral plexopathies

Brachial and Lumbosacral Plexopathies

The brachial and lumbosacral plexuses are complex neural structures that transmit sensory, motor, and autonomic information between the spinal cord and the extremities. Plexus disorders can be particularly disabling because lesions in the plexus usually affect large groups of nerve fibers originating from several spinal levels. Electrodiagnostic studies are often required to confirm a plexus lesion and determine the extent of injury and prognosis. Magnetic resonance is the imaging modality of choice for detecting intrinsic nerve abnormalities; recently, high-resolution ultrasound has emerged as an alternative method for dynamic evaluation and visualization of internal nerve architecture. Once a plexopathy is confirmed, the list of possible etiologies is relatively limited and includes traumatic and nontraumatic causes. Treatment relies on symptom management and physical rehabilitation unless a treatable underlying condition is found. Surgical approaches, including nerve grafts or tendon transfers, may improve limb function when spontaneous recovery is suboptimal.

Electrodiagnostic studies and new diagnostic modalities for evaluation of peripheral nerve disorders

Electrodiagnostic studies (EDx) are frequently performed in the diagnostic evaluation of peripheral nerve disorders. There is increasing interest in the use of newer, alternative diagnostic modalities, in particular imaging, either to complement or replace established EDx protocols. However, the evidence to support this approach has not been expansively reviewed. In this paper, diagnostic performance data from studies of EDx and other diagnostic modalities in common peripheral nerve disorders have been analyzed and described, with a focus on radiculopathy, plexopathy, compressive neuropathies, and the important neuropathy subtypes of Guillain-Barré syndrome, chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), vasculitic neuropathy and diabetic neuropathy. Overall EDx retains its place as a primary diagnostic modality in the evaluated peripheral nerve disorders. Magnetic resonance imaging and ultrasound have developed important complementary diagnostic roles in compressive and traumatic neuropathies and atypical CIDP, but their value is more limited in other neuropathy subtypes. Identification of hourglass constriction in nerves of patients with neuralgic amyotrophy may have therapeutic implications. Investigation of radiculopathy is confounded by poor correlation between clinical features and imaging findings and the lack of a diagnostic gold standard. There is a need to enhance the literature on the utility of these newer diagnostic modalities.

Magnetic Resonance Neurography of the Lumbosacral Plexus

Pain and weakness in the low back, pelvis, and lower extremities are diagnostically challenging, and imaging can be an important step in the workup and management of these patients. Technical advances in magnetic resonance neurography (MRN) have significantly improved its utility for imaging the lumbosacral plexus (LSP). In this article, the authors review LSP anatomy and selected pathology examples. In addition, the authors will discuss technical considerations for MRN with specific points for the branch nerves off the plexus.

Bruns Garland Syndrome as the first presentation of type 2 diabetes: two case reports and a practical approach to diagnosis

BACKGROUND

Diabetes is a global health problem causing a significant burden on the healthcare systems both due to the disease itself and associated complications. Diabetic radiculoplexus neuropathies or Bruns-Garland syndrome constitutes a rare form of microvascular complications, more commonly affecting the lumbosacral plexus and, very rarely, the cervical plexus. We describe two Sri Lankan males who presented with diabetic lumbosacral radiculoplexus neuropathy and diabetic cervical radiculoplexus neuropathy as the initial manifestation of diabetes.

CASE DESCRIPTION

Case 1: a 49-year-old Sri Lankan hotel chef presented with subacute painful weakness and wasting of the left upper arm for 3 months and weight loss. Left upper limb proximal muscles were wasted with diminished power and reflexes. A nerve conduction study showed comparative amplitude reduction. An electromyogram revealed positive sharp waves, frequent fibrillations, and high amplitude polyphasic motor unit potentials with reduced recruitment in proximal muscles of left upper limb. Case-2: a 47-year-old Sri Lankan carpenter presented with subacute progressive asymmetrical painful weakness and wasting of bilateral thighs for 5 months and weight loss. Lower limb proximal muscles were wasted with reduced power and knee jerks. The nerve conduction study was normal. The electromyogram was similar to case 1 involving both quadratus femoris muscles, which was more prominent on the left side. The work up for an underlying etiology revealed only elevated fasting blood glucose and HbA1c, suggesting a new diagnosis of diabetes associated with neurological symptoms. Patient 1 was diagnosed with diabetic cervical radiculoplexus neuropathy and patient 2 with diabetic lumbosacral radiculoplexus neuropathy. Both showed significant improvement following optimization of glycemic control together with symptomatic treatment and physiotherapy.

CONCLUSION

Diagnosis of diabetic radiculoplexus neuropathy requires a comprehensive workup to rule out other sinister pathologies. This case report has a dual importance; it describes diabetic radiculoplexus neuropathy as the very first manifestation of two previously healthy people, giving rise to a new diagnosis of diabetes and, at the same time, reporting on diabetic cervical radiculoplexus neuropathy, which is extremely rare and has never been previously reported in Sri Lanka.

Femoral neuropathy: A clinical and electrodiagnostic review

INTRODUCTION/AIMS

Femoral neuropathies can cause severe, prolonged debility, yet there have been few clinical and electrodiagnostic (EDx) studies addressing this condition. The aim of this study was to better understand the etiologies, EDx features, and clinical course of femoral neuropathy.

METHODS

We identified patients evaluated at Mayo Clinic Rochester between January 1, 1999 and July 31, 2019, with possible new femoral neuropathy ascertained via International Classification of Diseases-versions 9 and 10 diagnosis codes presenting within 6 months of symptom onset.

RESULTS

A retrospective review of 1084 records was performed and we ultimately identified 159 patients with isolated femoral neuropathy for inclusion. The most common femoral neuropathy etiologies were compressive (40%), perioperative stretch (35%), and inflammatory (6%). Presenting symptoms included weakness (96%), sensory loss (73%), and pain (53%). Presenting motor physical exam findings demonstrated moderate weakness (34%) or no activation (25%) of knee extension and mild (32%) or moderate (35%) weakness of hip flexion. Seventy-two percent of patients underwent EDx testing, including 22 with femoral motor nerve conduction studies. Treatment often involved physical therapy (89%) and was otherwise etiology-specific. In patients with follow-up data available (n = 154), 83% had subjective clinical improvement at follow-up with a mean time to initial improvement of 3.3 months and mean time to recovery at final follow-up of 14.8 months. Only 48% of patients had nearly complete or complete recovery.

DISCUSSION

In our cohort, the most common etiologies of femoral neuropathy were compression or perioperative stretch with high initial morbidity. Although motor recovery is common, improvement is often prolonged and incomplete.

Utility of Sensory Nerve Conduction Study in Radiologically Positive Lumbosacral Plexopathy

MRI is the most appropriate imaging method for visual evaluation of lumbosacral plexopathy (LSP) and a reference for comparing with nerve conduction study (NCS). Eight patients with clinical, electrophysiological, and lumbosacral plexus MRI findings suggestive of LSP were prospectively recruited. Saphenous nerve abnormalities were present in seven patients (88%), compared to three for the superficial fibular (38%), and three for the sural nerve (38%). MRI showed tumor, hematoma, abscess, contrast enhancement, or hyperintense signals on the T2-weighted sequences. The SN has the highest yield in MRI positive LSP and may be a vital adjunct for electrophysiological evaluation of LSP.

Focal inflammatory neuropathies

This chapter focuses on neuropathies that present with focal involvement of nerve roots, plexus, and/or peripheral nerves associated with autoimmune and inflammatory mechanisms that present with focal involvement of nerve roots, plexus and/or peripheral nerves. The clinical presentation, diagnosis, and treatment of focal autoimmune demyelinating neuropathies, focal nonsystemic vasculitic disorders (diabetic and nondiabetic radiculoplexus neuropathies, postsurgical inflammatory neuropathy, and neuralgic amyotrophy), and focal neuropathies associated with sarcoidosis and bacterial and viral infections are reviewed.

An Updated Review of Magnetic Resonance Neurography for Plexus Imaging

Magnetic resonance neurography (MRN) is increasingly used to visualize peripheral nerves in vivo. However, the implementation and interpretation of MRN in the brachial and lumbosacral plexi are challenging because of the anatomical complexity and technical limitations. The purpose of this article was to review the clinical context of MRN, describe advanced magnetic resonance (MR) techniques for plexus imaging, and list the general categories of utility of MRN with pertinent imaging examples. The selection and optimization of MR sequences are centered on the homogeneous suppression of fat and blood vessels while enhancing the visibility of the plexus and its branches. Standard 2D fast spin-echo sequences are essential to assess morphology and signal intensity of nerves. Moreover, nerve-selective 3D isotropic images allow improved visualization of nerves and multiplanar reconstruction along their course. Diffusion-weighted and diffusion-tensor images offer microscopic and functional insights into peripheral nerves. The interpretation of MRN in the brachial and lumbosacral plexi should be based on a thorough understanding of their anatomy and pathophysiology. Anatomical landmarks assist in identifying brachial and lumbosacral plexus components of interest. Thus, understanding the varying patterns of nerve abnormalities facilitates the interpretation of aberrant findings.

Differentiating Lumbar Spinal Etiology from Peripheral Plexopathies

Clinicians have managed and treated lower back pain since the earliest days of practice. Historically, lower back pain and its accompanying symptoms of radiating leg pain and muscle weakness have been recognized to be due to any of the various lumbar spine pathologies that lead to the compression of the lumbar nerves at the root, the most common of which is the radiculopathy known as sciatica. More recently, however, with the increased rise in chronic diseases, the importance of differentially diagnosing a similarly presenting pathology, known as lumbosacral plexopathy, cannot be understated. Given the similar clinical presentation of lumbar spine pathologies and lumbosacral plexopathies, it can be difficult to differentiate these two diagnoses in the clinical setting. Resultingly, the inappropriate diagnosis of either pathology can result in ineffective clinical management. Thus, this review aims to aid in the clinical differentiation between lumbar spine pathology and lumbosacral plexopathy. Specifically, this paper delves into spine and plexus anatomy, delineates the clinical assessment of both pathologies, and highlights powerful diagnostic tools in the hopes of bolstering appropriate diagnosis and treatment. Lastly, this review will describe emerging treatment options for both pathologies in the preclinical and clinical realms, with a special emphasis on regenerative nerve therapies.

Role of MR Neurography for Evaluation of the Lumbosacral Plexus: A Scoping Review

Purpose

MR neurography (MRN) is an imaging technique optimized to visualize the peripheral nerves. This review aimed to discover an optimized protocol for MRN of the lumbosacral plexus (LSP) and identify evidence for the clinical benefit of lumbosacral plexopathies.

Materials and Methods

We performed a systematic search of the two medical databases until September 2021. 'Magnetic resonance imaging', 'lumbosacral plexus', 'neurologic disease', or equivalent terms were used to search the literature. We extracted information on indications, MRN protocols for LSP, and clinical efficacy from 55 studies among those searched.

Results

MRN of the LSP is useful for displaying the distribution of peripheral nerve disease, guiding perineural injections, and assessing extraspinal causes of sciatica. Three-dimensional short-tau inversion recovery turbo spin-echo combined with vascular suppression is the mainstay of MRN.

Conclusion

Future work on the MRN of LSP should be directed to technical maturation and clinical validation of efficacy.

Evaluation of dynamic F wave parameters before and after physical activity in normal population

Objectives

F wave is one of the nerve conduction studies, mainly used to study the proximal pathway of peripheral nerves. One of its applications is dynamic assessment, i.e., before and after physical activity, when symptoms develop in some patients. Best to our knowledge, few studies evaluate normal dynamic F wave values in healthy individuals. This study aims to determine and compare normal values of several parameters of Compound Muscle Action Potential (CMAP) and F waves of tibial nerves dynamically before and after physical activity in the lower extremities of 34 normal subjects. These parameters were recorded before and after 15 min of continuous walking at intervals of 1, 5, and 10 min after the end of physical activity.

Results

Normal values of CMAP onset latency and amplitude, minimum, maximum, and mean latency of 10 F waves, F chronodispersion, and F persistence were dynamically collected before and during 10 min after physical activity in three phases. Some of the parameters showed significant changes (P < 0.05). Although physical activity showed statistically significant effects on some CMAP and F wave parameters (especially F chronodispersion) in normal subjects, none of them exceeded the normal clinical values introduced in the literature.

Case report: Corticosteroids-induced acute diabetic peripheral neuropathy

A 62-year-old man was diagnosed as IgA nephropathy. He had a pancreatic tumor operation 19 years ago and had a normal plasma glucose test every year. One month after the medication of prednisolone acetate was administered his fasting plasma glucose elevated to 7.1mmol/L while he manifested symptoms of thirst, frequent urination, and weight loss. Approximately 3 months after the steroids, he started complaining of numbness, weakness, and muscle cramp in his lower extremities, blood tests showed elevated plasma glucose and electromyography (EMG) revealed impairment of the peripheral nerves in the lower extremity, diabetic peripheral neuropathy was diagnosed. Mecobalamin and Acupuncture were employed and steroids were discontinued, 8 months later he recovered part of his strength and sensation. This case presents a specific adverse drug reaction of corticosteroids that causes diabetes mellitus and subsequently leads to peripheral neuropathy in an acute onset.

A cook with 'burning in the thigh' and a 'hotspot' in the groin!

Meralgia paresthetica (MP) is a condition characterised by abnormal sensations on the anterolateral aspect of the thigh due to the dysfunction of the lateral femoral cutaneous nerve. Here, I present a case of a 64-year-old female cook who attended the General Medicine clinic with 2 months of persistent numbness and 'burning' sensation over the right anterolateral thigh. Subsequent physical examination revealed the diagnosis of meralgia paresthetica. The significance of good history taking and thorough physical examination in reaching the diagnosis of meralgia paresthetica cannot be overemphasized. In most typical presentations, advanced imaging and neurodiagnostic testing do not add value to confirm the diagnosis. If the clinical diagnosis is doubtful, nerve conduction study and magnetic resonance imaging may still be performed to exclude other mimicking pathologies. Increasing awareness of MP among doctors unfamiliar with this condition will prevent the ordering of excessive investigations.

Electrodiagnostic Assessment of Plexopathies

Disorders of the brachial and lumbosacral plexus are complex and may occur as a consequence of trauma, compression, inflammatory disorders, malignant infiltration, or delayed effects of radiation therapy. An understanding of plexus anatomy and surrounding structures will allow the electromyographer to facilitate an efficient and comprehensive assessment of the plexus. A careful and thorough electrodiagnostic assessment allows for localization within the plexus and may provide important information about underlying pathology and prognosis.

Sacral plexus disorder caused by a wooden toothpick in the rectum

A 67-year-old man presented with a 2-month history of pain in his right buttock and lower limb. MRI depicted right L5/S1 lateral recess stenosis requiring surgical treatment; however, preoperative CT showed an approximately 7 cm long, thin, rod-shaped structure in the rectum, which was ultimately determined to be an accidentally ingested toothpick. It was removed surgically 6 days after diagnosis, because right leg pain worsened rapidly. The pain disappeared thereafter, and the symptoms have not recurred since. The pain might have been localised to the right buttock and posterior thigh in the early stages because the fine tip of the toothpick was positioned to the right of the anterior ramus of the S2 spinal nerve. Although sacral plexus disorder caused by a rectal foreign body is extremely rare, physicians should be mindful to avoid misdiagnosis.

Idiopathic Lumbosacral Neuropathy Syndrome: Case Report

Idiopathic lumbosacral plexitis or lumbosacral radiculoplexus neuropathy is a disease characterized by nerve damage in lumbar and/or sacral plexus without trauma, mass effect or diabetic complications. A 47-year-old male patient with right groin pain and loss of right leg muscle strength is presented in this case report. Neuropathy was detected in the L4 nerve root by electromyography and magnetic resonance neurrographic imaging. The underlying cause was investigated; however, it is linked to the idiopathic outcome. Idiopathic lumbosacral neuropathy is a lumbosacral plexus disease in which no underlying pathology plays a role in causing severe pain and muscle weakness. Patients should be avoided urgently operation because of the sudden onset symptoms.

Brachial and lumbosacral plexopathies: A review

Diseases of the brachial and lumbosacral plexus are uncommon and complex. The diagnosis of plexopathies is often challenging for the clinician, both in terms of localizing a patient's symptoms to the plexus as well as determining the etiology. The non-specific clinical features and similar presentations to other root, nerve, and non-neurologic disorders emphasize the importance of a high clinical index of suspicion for a plexopathy and comprehensive clinical evaluation. Various diagnostic tests, including electrodiagnostic (EDX) studies, neuroimaging (including ultrasound, MRI, or PET), serologic studies, and genetic testing, may be used to confirm a plexopathy and assist in identifying the underlying etiology. EDX testing plays an important role in confirming a plexopathy defining the localization, pathophysiology, chronicity, severity, and prognosis. Given the complexity of the plexus anatomy, multiple common and uncommon NCS and an extensive needle examination is often required, and a comprehensive, individualized approach to each patient is necessary. Treatment of plexopathies often focuses on symptomatic management although, depending on the etiology, specific targeted treatments may improve outcome. This article reviews the clinical features, EDX approaches, and evaluation and treatment of brachial and lumbosacral plexopathies.

Enhanced MR neurography of the lumbosacral plexus with robust vascular suppression and improved delineation of its small branches

PURPOSE

To evaluate whether gadolinium enhanced 3D SPACE STIR sequence technique increases the visualization of the lumbosacral plexus (LSP) and its small branches.

METHODS

A retrospective study was performed on 24 patients who had underwent 3D SPACE STIR sequences scan with and without the administration of gadolinium contrast. In this study, we focused on the healthy sides of the LSP and its branches in each patient. The contrast ratio (CR), contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR) were objectively calculated by two experienced radiologists. The subjective visualization scores of the branches that were vitally important to therapeutic decision-making including femoral nerves, obturator nerves, lumbosacral trunks, superior gluteal and extra-pelvic sciatic nerves, were assessed using post-processing images.

RESULTS

Of the 24 subjects, all LSP nerve roots, femoral nerves, lumbosacral trunks and sciatic nerves were illustrated on both contrast-enhanced and non-contrast images. The enhanced images were found to have higher nerve to vein CNRs compared to non-contrast images. Compared to non-contrast images, the CRs of nerves versus surrounding fat tissues, bones, veins and muscles were improved in contrast-enhanced images, while the SNRs were better but not significantly so. Targeted maximum intensity projection (MIP) nerves including femoral, obturator, superior gluteal and extra-pelvic sciatic nerves obtained significantly higher subjective scores when gadolinium was administered.

CONCLUSIONS

The gadolinium enhanced 3D SPACE STIR sequence provided superior vascular suppression, resulting in increased conspicuity of LSP and its small branches. Altogether, this shows great potential for therapeutic decision-making in traumatic LSP lesions cases.

Spectrum of diabetic neuropathies

The diabetic state results in neuropathy. The main causative mechanism is hyperglycemia, although microvascular involvement, hypertriglyceridemia, as well as genetic and immune mechanisms may be contributory. There is a growing spectrum of types of diabetic neuropathies that differ based on the type of fibers involved (e.g. myelinated, unmyelinated, autonomic, somatic), distribution of nerves involved, and mechanisms of neuropathy. The most common type is distal sensory neuropathy (DSN), which affects the distal ends of large myelinated fibers, more often sensory than motor, and is often asymptomatic. The next-most common is distal small fiber neuropathy (DSFN), which largely affects the unmyelinated fibers and carries the phenotype of burning feet syndrome. Diabetic autonomic neuropathy (DAN) occurs when widespread involvement of autonomic unmyelinated fibers occurs, and patients can be incapacitated with orthostatic hypotension as well as neurogenic bladder and bowel involvement. Radiculoplexus diabetic neuropathy causes proximal weakness and pain, usually in the lower extremity, and has a combination of immune, inflammatory, and vascular mechanisms. The nerve roots and plexus are involved. These patients present with proximal weakness of a subacute onset, often with severe pain and some autonomic failure. Finally, rapid and sustained reduction of blood glucose can result in treatment-induced diabetic neuropathy (TIND), which largely affects the sensory and autonomic fibers. This occurs if HbA1c is rapidly reduced within 3 months, and the likelihood is proportional to the original A1c and the size of the reduction.

Diabetic amyotrophy: a painful radiculoplexus neuropathy

Diabetic lumbosacral radiculoplexus neuropathy is a monophasic syndrome of diffuse pain and weakness that typically affects the lower limbs asymmetrically and is often associated with significant weight loss. Recovery can be prolonged and unpredictable. It is a clinical diagnosis and investigations are performed mainly to exclude other causes. Although it is most likely caused by a microvasculitis, there is no evidence to support using intravenous immunoglobulin or any long-term immunosuppression. Pulsed methylprednisolone may help pain if given within 2–3 months of symptom onset.

Lumbosacral Plexopathy Caused by Presacral Recurrence of Colon Cancer Mimicking Degenerative Spinal Disease: A Case Report

Radiculopathy triggered by degenerative spinal disease is the most common cause of spinal surgery, and the number of affected elderly patients is increasing. Radiating pain that is extraspinal in origin may distract from the surgical decision on how to treat a neurological presentation in the lower extremities. A 54-year-old man with sciatica visited our outpatient clinic. He had undergone laminectomy and discectomy to treat spinal stenosis at another hospital, but his pain remained. Finally, he was diagnosed with a plexopathy caused by late recurrence of colorectal cancer, which compressed the lumbar plexus in the presacral area. This case report illustrates the potential for misdiagnosis of extraspinal plexopathy and the value of obtaining an accurate history. Although the symptoms are similar, spinal surgeons should consider both spinal and extraspinal origins of sciatica.

Painful lumbosacral plexopathy: a case report

Patients frequently suffer from lumbosacral plexus disorder. When conducting a neurological examination, it is essential to assess the extent of muscle paresis, sensory disorder distribution, pain occurrence, and blocked spine. An electromyography (EMG) can confirm axonal lesions and their severity and extent, root affliction (including dorsal branches), and disorders of motor and sensory fiber conduction. Imaging examination, particularly gadolinium magnetic resonance imaging (MRI) examination, ensues. Cerebrospinal fluid examination is of diagnostic importance with radiculopathy, neuroinfections, and for evidence of immunoglobulin synthesis. Differential diagnostics of lumbosacral plexopathy (LSP) include metabolic, oncological, inflammatory, ischemic, and autoimmune disorders.In the presented case study, a 64-year-old man developed an acute onset of painful LSP with a specific EMG finding, MRI showing evidence of plexus affliction but not in the proximal part of the roots. Painful plexopathy presented itself with severe muscle paresis in the femoral nerve and the obturator nerve innervation areas, and gradual remission occurred after 3 months. Autoimmune origin of painful LSP is presumed.We describe a rare case of patient with painful lumbar plexopathy, with EMG findings of axonal type, we suppose of autoimmune etiology.

Coexisting Upper Lumbar-Disc Herniation and Lumbosacral Radiculoplexus Neuropathy: A Diagnostic Challenge: A Case Report

CASE

An elderly man presented with nontraumatic, acute onset of paralysis of the right quadriceps and the hip flexors, adductors, and abductors without backache or signs of nerve-root tension. Magnetic resonance imaging showed evidence of upper lumbar-disc extrusion with foraminal stenosis as well as right-sided inflammatory lumbar plexitis involving the L2, L3, and L4 nerve roots. However, the pattern of neurological involvement and relatively rapid and full recovery following treatment with parenteral corticosteroids suggested a diagnosis of chemical radiculitis.

CONCLUSION

It is important to differentiate chemical radiculitis from both lumbar plexopathy and a herniated nucleus pulposus because it can be treated nonoperatively, with the expectation of a relatively rapid and full recovery.