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.

Clinical, Neurophysiologic, and Pathologic Features in Patients With Early-Onset Postradiation Neuropathy.

OBJECTIVES: The objective of this study was to study early-onset radiation-induced neuropathy reviewing neurologic course, steroid response, and available nerve biopsies. METHODS: Patients coded with radiation-induced neuropathy within 6 months of radiation were reviewed from January 1,1999, to August 31, 2022. Patients had to have electrodiagnostically confirmed neuropathy localized within or distal to radiation fields. Neurologic course and nerve biopsies were reviewed. RESULTS: Twenty-eight patients (16 male and 12 female patients, mean age 63.8 years) were identified. The average radiation dose was 4,659 cGy (range 1,000-7,208). Tumor infiltration was not observed on MRI and PET. Postradiation onsets averaged 2 months (range 0-5). Localizations included brachial (n = 4) plexopathies, lumbosacral (n = 12) plexopathies, radiculopathies (n = 10), and mononeuropathies (n = 2). Neuropathic pain (n = 25) and weakness (n = 25) were typical. The clinical courses were subacute monophasic (n = 14), chronic progressive (n = 8), or static (n = 1), and 5 were without follow-up. Nerve biopsies (n = 8) showed an inflammatory ischemic process with perivascular inflammatory infiltrates (n = 7) or microvasculitis (n = 2). Nine patients, 7 with monophasic courses, received steroid burst therapy with symptom improvement in 8. No patients recovered entirely back to baseline. DISCUSSION: In contrast to chronic radiation-induced neuropathy, early-onset patients most commonly have painful monophasic courses with residual deficits, possibly steroid responsive. An ischemic inflammatory pathogenesis is suggested.

Assessing electrodiagnostic skills among residents and fellows: Relationships between workplace-based assessments using the Electromyography Direct Observation Tool and other measures of trainee performance.

INTRODUCTION/AIMS: Graduate medical education programs must ensure residents and fellows acquire skills needed for independent practice. Workplace-based observational assessments are informative but can be time- and resource-intensive. In this study we sought to gather "relations-to-other-variables" validity evidence for scores generated by the Electromyography Direct Observation Tool (EMG-DOT) to inform its use as a measure of electrodiagnostic skill acquisition. METHODS: Scores on multiple assessments were compiled by trainees during Clinical Neurophysiology and Electromyography rotations at a large US academic medical center. Relationships between workplace-based EMG-DOT scores (n = 298) and scores on a prerequisite simulated patient exercise, patient experience surveys (n = 199), end-of-rotation evaluations (n = 301), and an American Association of Neuromuscular & Electrodiagnostic Medicine (AANEM) self-assessment examination were assessed using Pearson correlations. RESULTS: Among 23 trainees, EMG-DOT scores assigned by physician raters correlated positively with end-of-rotation evaluations (r = 0.63, P = .001), but EMG-DOT scores assigned by technician raters did not (r = 0.10, P = .663). When physician and technician ratings were combined, higher EMG-DOT scores correlated with better patient experience survey scores (r = 0.42, P = .047), but not with simulated patient or AANEM self-assessment examination scores. DISCUSSION: End-of-rotation evaluations can provide valid assessments of trainee performance when completed by individuals with ample opportunities to directly observe trainees. Inclusion of observational assessments by technicians and patients provides a more comprehensive view of trainee performance. Workplace- and classroom-based assessments provide complementary information about trainee performance, reflecting underlying differences in types of skills measured.

Delayed-Onset Heparin-Induced Thrombocytopenia With Cerebral Venous Sinus Thrombosis Following Total Knee Arthroplasty: Case Report.

Heparin-induced thrombocytopenia (HIT) is a prothrombotic state caused by autoantibodies against platelet factor 4 (PF4)-heparin complexes. Although HIT typically presents 5-10 days after the initiation of heparin, thrombosis and thrombocytopenia may occur up to several weeks following heparin withdrawal, so-called delayed-onset HIT. Although rare, there have been isolated reports of HIT-induced cerebral venous sinus thrombosis (CVST), which carry high rates of morbidity and mortality. There is a need to further characterize the etiology, clinical presentation, treatment paradigms, and outcomes of patients with HIT-induced CVST. Here, we present the case of a 57-year old female who presented to the emergency department with a headache and seizure 11 days following a right total knee arthroplasty for which she received 3 post-operative doses of enoxaparin. Work-up demonstrated acute intracerebral hemorrhage (ICH), CVST, and thrombocytopenia. Intravenous heparin resulted in rapidly deteriorating platelet count and subsequent serologic testing confirmed the diagnosis of HIT. Treatment with bivalirudin was initiated, the HIT resolved, and the patient was discharged home on hospital day 19 with long-term anticoagulation mediated by warfarin. At 3-month follow up, the patient had mild upper motor neuron pattern weakness and was living independently. This case depicts a rare case of delayed-onset HIT and CVST, highlights the importance of establishing a fluid treatment plan for managing HIT-induced CVST, and illustrates the importance of employing rapid anticoagulation despite acute ICH to achieve a desirable clinical outcome.

First- and Third-Trimester Urinary Phthalate Metabolites in the Development of Hypertensive Diseases of Pregnancy.

The purpose of this study was to determine whether maternal urinary phthalate metabolite concentrations are associated with the development of higher blood pressure or pregnancy-induced hypertension (PIH). Participants were women without chronic hypertension who enrolled in The Infant Development and the Environment Study, a prospective pregnancy cohort conducted at four U.S. academic medical centers from 2010-2012. Prenatal records were reviewed to obtain blood pressure measurements and diagnoses of PIH (gestational hypertension, preeclampsia, eclampsia, and HELLP syndrome, defined as hemolysis, elevated liver enzymes, and low platelet count). Complete-case analyses used multivariable linear and logistic regression for analysis of blood pressure measurements and PIH diagnoses, respectively. In the final dataset (N = 668), higher concentrations of first-trimester monoethyl phthalate (MEP) and mono-3-carboxypropyl phthalate (MCPP) and third-trimester mono-isobutyl phthalate (MiBP) were significantly associated with a medical chart diagnosis of PIH. First-trimester mono-n-butyl phthalate (MBP) and MEP along with the sum of di-(2-ethylhexyl) phthalate metabolites (∑DEHP) were each associated with increased systolic blood pressure across pregnancy. In conclusion, several phthalate metabolite concentrations were significantly associated with PIH and greater increases in systolic blood pressure across pregnancy.

MuSK Myasthenia Gravis Presenting with Bilateral Vocal Cord Abduction Paresis: A Case Report and Literature Review.

INTRODUCTION: Approximately 39% to 49% of patients with previously diagnosed acetylcholine receptor antibody-negative myasthenia gravis have been found to be muscle-specific tyrosine kinase (MuSK) antibody positive. These patients have a presentation that typically includes oculobulbar weakness, poorer response to cholinesterase inhibitors, and higher risk for acute clinical decompensation that necessitates plasma exchange. MuSK patients can require more aggressive maintenance immunosuppression earlier-on to maintain stability, often with rituximab. CASE REPORT: The authors report the case of a 45-year-old woman who presented with months of worsening hoarseness and exertional dyspnea. Laryngoscopy revealed limited abduction of vocal cords bilaterally as the source of the complaint. Examination revealed ophthalmoparesis and fatigable proximal muscle weakness. She was found to have elevated MuSK antibodies that, along with evidence of neuromuscular junction transmission defect on nerve conduction studies, confirmed the diagnosis of MuSK myasthenia gravis. She experienced no improvement with pyridostigmine and decompensated despite receiving oral steroids, requiring intubation. However, she dramatically improved with plasma exchange and has since been doing well on rituximab therapy. CONCLUSION: Dysphonia with hoarse quality secondary to vocal cord abduction paresis is a rare presentation of myasthenia gravis, as opposed to the typical flaccid dysarthria seen in bulbar myasthenia and should raise suspicion for MuSK antibody positivity. MuSK myasthenia gravis cases can be more refractory to treatment with cholinesterase inhibitors and are more likely to cause exacerbations and myasthenia crisis. Therefore, early and accurate diagnosis with appropriate antibody testing is imperative to avoid delays in treatment to prevent potentially life-threatening outcomes.

Supplemental oxygen reverses hypoxia-induced smooth muscle cell proliferation by modulating HIF-alpha and VEGF levels in a rabbit arteriovenous fistula model.

BACKGROUND: Numerous mechanisms for the formation of intimal hyperplasia have been proposed but none have been proven or accepted. Our research focuses on the potential role of hypoxia-inducible factors (HIFs), vascular endothelial growth factor (VEGF), and platelet-derived growth factors as well as the extracellular signal-regulated kinase (ERK), phosphatidylinositide 3-kinase /protein Kinase B (PI3-K/AKT) pathway in hypoxia-mediated intimal hyperplasia processes. We hypothesize that HIF and VEGF will be downregulated with supplemental oxygen in our arteriovenous fistula rabbit model. METHODS: Rabbits were randomized into different experimental groups with varying oxygen exposure (21% O2 or 30% O2) and receipt of surgery (surgery with fistula formation, no surgery, or sham operation with skin incision only). Plasma samples were collected at designated intervals in which cytokines and smooth muscle cell proliferation were measured. In addition, cell specimens were exposed to hyperoxic, normoxic, and hypoxic environments with cytokines measured at various time points. RESULTS: Placement of an arteriovenous fistula resulted in hypoxia-induced HIF stabilization with a concurrent increase in VEGF levels. There was a 4.2-fold induction in HIF-1α levels in animals that were placed in normal air after surgery when compared with animals that were exposed to hyperoxic air. Also, VEGF level significantly increased after surgery in the normoxic group, reaching a maximum of 959 pg/mL. Plasma VEGF levels in the surgery and supplemental oxygen group were significantly lower than the normoxic surgery group with almost a 45% reduction in plasma VEGF levels (524 pg/mL). Activation of VEGF receptors on smooth muscle cells through ERK1 and AKT pathways resulted in significant smooth muscle cell proliferation and migration. These effects are dramatically reduced in animals that are exposed to a hyperoxic environment of 30% oxygen. CONCLUSIONS: Our results suggest that short-term administration of supplemental oxygen inhibits HIFs and VEGF signaling to reduce smooth muscle proliferation in the local blood vessel. These results provide strong support for the therapeutic use of supplemental oxygen after arterial surgery to reduce intimal hyperplasia. These findings also provide a nidus for future clinical trials to determine whether this is clinically applicable in humans.