Autoimmunity and postural orthostatic tachycardia syndrome: Implications in diagnosis and management.

Postural orthostatic tachycardia syndrome (POTS)-sustained tachycardia upon standing without orthostatic hypotension-can be diagnosed clinically without an extensive diagnostic evaluation unless certain atypical features suggest an alternative diagnosis. A unifying pathophysiologic mechanism has not been identified, although several have been proposed. Similarities between POTS and various autoimmune disorders suggest an immune mechanism in a subset of patients. However, no causative antibody has been identified, and associated antibodies are rarely clinically relevant. Moreover, immunotherapies are not currently recommended for POTS, although clinical trials are underway to clarify their utility.

Myelin oligodendrocyte glycoprotein (MOG) antibodies in a patient with glioblastoma: Red flags for false positivity.

We present a patient with positive medium titer MOG-IgG and progressive neurological decline whose clinical and radiological phenotype were not consistent with a MOG-IgG associated disorder and ultimately received a diagnosis of glioblastoma after brain biopsy and died 4 weeks later. This represents an important topic with a high frequency of MOG-IgG testing in clinical practice. Due to this there are increasing reports of MOG-IgG positivity in atypical clinical phenotypes, raising the possibility of false positives, which can have important implications. It is important to highlight that judicious clinical evaluation is needed when interpreting MOG-IgG results in atypical settings.

Prevalence of denervation in the intrinsic foot muscles in patients with distal predominantly small fiber neuropathy.

BACKGROUND: We aimed to evaluate the significance of electromyographic findings in the intrinsic foot muscles (IFMs) of patients with skin biopsy proven small fiber neuropathy (SFN). METHODS: This was a single-center retrospective analysis of patients who underwent skin biopsy for intra-epidermal nerve fiber density (IENFD) measurement and electrodiagnostic (EDX) study for evaluation of polyneuropathy. RESULTS: A total of 1416 patents with normal lower extremity EDX studies proximal to the foot were included. Active denervation was seen in 16.1% of IFMs in patients with skin biopsy proven SFN and 4.1% of patients without SFN (P < .0001). Reinnervation changes without active denervation were observed in 30.4% of SFN patients and 23.8% of patients without SFN (P = .01). IENFD was lower in SFN patients with active denervation in IFMs than without (P < .0001). CONCLUSIONS: Evaluation of active denervation in the IFMs can reveal large fiber dysfunction in SFN patients with otherwise normal routine EDX findings.

Longitudinal follow-up of biopsy-proven small fiber neuropathy.

INTRODUCTION: Little is published on the prognosis of small fiber neuropathy (SFN). METHODS: A retrospective analysis of 101 patients with biopsy proven SFN. RESULTS: Study participants included 87 patients with length-dependent SFN and 14 patients with non-length-dependent SFN. The average duration of symptoms was 3.2 years prior to SFN diagnosis, and the average follow-up duration after diagnosis was 6.2 years. Neuropathic pain was present in 98% of patients and in 84.2% of patients at the final visit. The average total number of pain medications ever used was 4.4 per patient. Signs of autonomic dysfunction were initially present in 24.8% of patients, but improved in most. Large fiber involvement was seen in 11.9% of patients. Small fiber neuropathy affected employment and ambulation status in 5.3% and 6.3% of patients, respectively. DISCUSSION: Small fiber neuropathy tends to be stable and rarely affects ambulation and employment status. Effective pain control remains a challenge.

Sural sensory nerve action potential, epidermal nerve fiber density, and quantitative sudomotor axon reflex in the healthy elderly.

INTRODUCTION: Polyneuropathy evaluation in older patients is often challenging due to conflicting data regarding normative values for peripheral nerve testing. METHODS: We characterized the results of sural nerve conduction studies, intraepidermal nerve fiber density (IENFD), and quantitative sudomotor axon reflex testing (QSART) in a prospective study of 50 healthy subjects aged ≥60 years. RESULTS: Of the 50 subjects, 48 (96%) had an obtainable sural sensory nerve action potential (SNAP). Using quantile regression, we estimated the lower limit of normal (LLN) for sural amplitudes to be 3 µV for patients 60-70 years, 1 µV for those 70-74 years, and <1 µV (absent) for those ≥75 years of age. IENFD and QSART volume were reduced with advancing age, although IENFD was lower in men and QSART volume was lower in women. CONCLUSIONS: We propose that an absent sural SNAP in patients up to 75 years of age should be considered abnormal. Our findings also support age- and gender-stratified normative data for IENFD and QSART.

Tentorial dural arteriovenous fistula presenting with quadriparesis: case report and review of the literature.

Tentorial dural arteriovenous fistulas (TDAVFs) draining into the spinal venous system are rare lesions. The clinical presentation can be devastating and the diagnosis delayed because of the initial nonspecific imaging and laboratory findings. We report a case of a 20-year-old woman with a rapidly progressive myelopathy, who was found to have a left TDAVF, fed by a single arterial feeder with drainage into the perimedullary venous system. The fistula was surgically clipped. The patient showed neurologic improvement at her 3-month follow-up but still had significant weakness of all 4 extremities. Early diagnosis is key as the neurologic symptoms are reversible with appropriate treatment. We review the relevant literature, imaging characteristics, and treatment modalities for TDAVF.

Pelvic nerve injury following gynecologic surgery: a prospective cohort study.

OBJECTIVE: The purpose of this study was to determine the incidence and time course of postoperative neuropathy resulting from gynecologic surgery. STUDY DESIGN: A single cohort of 616 female patients undergoing elective gynecologic surgery for benign or malignant conditions at a tertiary care academic medical center underwent a postoperative neurologic evaluation to identify postoperative neuropathy of the lower extremities. RESULTS: Fourteen peripheral nerve injuries were observed in 11 patients, making the overall incidence of postoperative neuropathy 1.8% (95% confidence interval, 1.0-3.2). Injury to the lateral femoral cutaneous (5), femoral (5), common fibular (1), ilioinguinal/iliohypogastric (1), saphenous (1), and genitofemoral (1) nerves were detected. Complete resolution of neuropathic symptoms occurred in all but 1 patient (91%). Median time to resolution of symptoms was 31.5 days (range, 1 day to 6 months). CONCLUSION: The incidence of lower extremity neuropathy attributable to gynecologic operations is low, and these neuropathies resolve in the great majority of cases.

Cervical radiculopathy.

Cervical radiculopathy is a condition encountered commonly in the evaluation of neck pain that may result in significant discomfort and functional deficits. Although the long-term prognosis of this condition is favorable, a standardized approach to therapy is important to minimize unnecessary tests and identify patients who require more urgent intervention. Patient education, pain control, and physical therapy are the first line of therapy. Patients who have protracted pain or significant functional deficits may require a more thorough evaluation, including imaging, electrodiagnostic testing, and, possibly, surgical referral. This article outlines the basic clinical, diagnostic, and therapy considerations in the evaluation of cervical radiculopathy.