Short-Acting Neuromuscular Blockade Improves Inter-rater Reliability of Median Somatosensory Evoked Potentials in Post-cardiac arrest Prognostication.

BACKGROUND: Although median nerve somatosensory evoked potentials are routinely used for prognostication in comatose cardiac arrest survivors, myogenic artifact can reduce inter-rater reliability, leading to unreliable or inaccurate results. To minimize this risk, we determined the benefit of neuromuscular blockade agents in improving the inter-rater reliability and signal-to-noise ratio of SSEPs in the context of prognostication. METHODS: Thirty comatose survivors of cardiac arrest were enrolled in the study, following the request from an intensivist to complete an SSEP for prognostication. Right and left median nerve SSEPs were obtained from each patient, before and after administration of an NMB agent. Clinical histories and outcomes were retrospectively reviewed. The SSEP recordings before and after NMB were randomized and reviewed by five blinded raters, who assessed the latency and amplitude of cortical and noncortical potentials (vs. absence of response) as well as the diagnostic quality of cortical recordings. The inter-rater reliability of SSEP interpretation before and after NMB was compared via Fleiss' κ score. RESULTS: Following NMB administration, Fleiss' κ score for cortical SSEP interpretation significantly improved from 0.37 to 0.60, corresponding to greater agreement among raters. The raters were also less likely to report the cortical recordings as nondiagnostic following NMB (40.7% nondiagnostic SSEPs pre-NMB; 17% post-NMB). The SNR significantly improved following NMB, especially when the pre-NMB SNR was low (< 10 dB). Across the raters, there were three patients whose SSEP interpretation changed from bilaterally absent to bilaterally present after NMB was administered (potential false positives without NMB). CONCLUSIONS: NMB significantly improves the inter-rater reliability and SNR of median SSEPs for prognostication among comatose cardiac arrest survivors. To ensure the most reliable prognostic information in comatose post-cardiac arrest survivors, pharmacologic paralysis should be consistently used before recording SSEPs.

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 type 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 mutations 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 the 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% confidence interval, 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.

Autonomic dysfunction following COVID-19 infection: an early experience.

PURPOSE: Post-COVID-19 syndrome is a poorly understood aspect of the current pandemic, with clinical features that overlap with symptoms of autonomic/small fiber dysfunction. An early systematic analysis of autonomic dysfunction following COVID-19 is lacking and may provide initial insights into the spectrum of this condition. METHODS: We conducted a retrospective review of all patients with confirmed history of COVID-19 infection referred for autonomic testing for symptoms concerning for para-/postinfectious autonomic dysfunction at Mayo Clinic Rochester or Jacksonville between March 2020 and January 2021. RESULTS: We identified 27 patients fulfilling the search criteria. Symptoms developed between 0 and 122 days following the acute infection and included lightheadedness (93%), orthostatic headache (22%), syncope (11%), hyperhidrosis (11%), and burning pain (11%). Sudomotor function was abnormal in 36%, cardiovagal function in 27%, and cardiovascular adrenergic function in 7%. The most common clinical scenario was orthostatic symptoms without tachycardia or hypotension (41%); 22% of patients fulfilled the criteria for postural tachycardia syndrome (POTS), and 11% had borderline findings to support orthostatic intolerance. One patient each was diagnosed with autoimmune autonomic ganglionopathy, inappropriate sinus tachycardia, vasodepressor syncope, cough/vasovagal syncope, exacerbation of preexisting orthostatic hypotension, exacerbation of sensory and autonomic neuropathy, and exacerbation of small fiber neuropathy. CONCLUSION: Abnormalities on autonomic testing were seen in the majority of patients but were mild in most cases. The most common finding was orthostatic intolerance, often without objective hemodynamic abnormalities on testing. Unmasking/exacerbation of preexisting conditions was seen. The temporal association between infection and autonomic symptoms implies a causal relationship, which however cannot be proven by this study.

Unusual presentation Of Sjögren-associated neuropathy with plasma cell-rich infiltrate.

INTRODUCTION: Sjögren syndrome is thought to be a lymphocyte-driven process. Peripheral nervous system involvement occurs in about 20%-25% of patients. A sensory-predominant, large-fiber peripheral neuropathy is most common, and it is usually associated with a subacute to chronic presentation. METHODS: We report a rare case of an acute Sjögren-associated, sensory predominant, length-dependent peripheral neuropathy mimicking Guillain-Barré syndrome. The patient presented with sensory ataxia preceded by fever and polyarthralgia. She gave a history of years of dry eyes and dry mouth. RESULTS: She had a positive Shirmer test, abnormal salivary gland scan, and positive SS-A and SS-B antibodies. A sural nerve biopsy showed an unusual, dense, non-IgG4, polyclonal, plasma-cell perivascular infiltrate. The patient responded to treatment with weekly pulse intravenous methylprednisolone. CONCLUSIONS: Sjögren syndrome can present with acute-onset, sensory predominant peripheral neuropathy. The role of plasma cells in Sjögren syndrome is unexplored and deserves further study. Muscle Nerve 55: 605-608, 2017.

Progressive polyradiculoneuropathy due to intraneural oxalate deposition in type 1 primary hyperoxaluria.

INTRODUCTION: A 24-year-old man with primary hyperoxaluria type 1 (PH1) presented with a rapidly progressive axonal and demyelinating sensorimotor polyradiculoneuropathy shortly after the onset of end-stage renal disease. His plasma oxalate level was markedly elevated at 107 µmol/L (normal<1.8 µmol/L). METHODS: A sural nerve biopsy was performed. Teased fiber and paraffin and epoxy sections were done and morphometric procedures were performed on this sample and on an archived sample from a 22-year-old man as an age- and gender-matched control. Embedded teased fiber electron microscopy was also performed. RESULTS: The biopsy revealed secondary demyelination and axonal degeneration. Under polarized light, multiple bright hexagonal, rectangular, and starburst inclusions, typical of calcium oxalate monohydrate crystals, were seen. CONCLUSIONS: The proposed mechanisms of nerve damage include disruption of axonal transport due to crystal deposition, toxic effect of oxalate, or nerve ischemia related to vessel occlusion from oxalate crystal deposition.

Clinicopathologic Findings in Patients With Paraneoplastic Neuropathies and Antibodies Strongly Associated With Cancer.

BACKGROUND AND OBJECTIVES: Pathologic descriptions of peripheral nerve involvement in paraneoplastic neuropathies are sparse, mostly from autopsies focusing on CNS and dorsal root ganglia tissues. Here, we describe the clinicopathologic features of peripheral nerve biopsies in patients with paraneoplastic neurologic syndromes to expand the currently limited knowledge. METHODS: Retrospective review of the Mayo Clinic electronic medical record from 1995 to 2022 for patients identified to have subacute onset neuropathy with paraneoplastic antibodies identified in our neuroimmunology laboratory having available nerve biopsies performed at the time of diagnosis. Patients with another cause of neuropathy not linked to their subacute onset were excluded. RESULTS: Nineteen patients met inclusion criteria: 4 with amphiphysin antibodies, 6 with antineuronal nuclear antibody (ANNA)-1 only, 3 with both ANNA-1 and collapsin response-mediator protein 5 (CRMP-5), 2 with ANNA-2, and 4 with CRMP-5 antibodies only. Fifteen biopsies had reduced the density of myelinated nerve fibers-4 with multifocality. Subperineurial edema was present in 17 biopsies. Prominent epineurial perivascular inflammation was present in 3 biopsies, all belonging to patients with a lumbosacral radiculoplexus neuropathy (LRPN) phenotype. DISCUSSION: Axonal loss, subperineurial edema, and an absence of prominent inflammation are the most common findings in nerve biopsies of patients with paraneoplastic antibodies strongly associated with cancer. The LRPN phenotype was the only subset with inflammatory collections. Paraneoplastic autoantibody testing should be considered in patients with subacute onset neuropathies, with or without interstitial inflammatory findings.

Amyloid-like IgM deposition neuropathy with multiple mononeuropathies and generalized neuropathy.

Amyloid-like IgM deposition neuropathy is a distinct entity in the setting of IgM monoclonal gammopathy in which endoneurial perivascular entire IgM-particle accumulation leads to a painful sensory followed by motor peripheral neuropathy. We report a 77-year-old man presenting with progressive multiple mononeuropathies starting with painless right foot drop. Electrodiagnostic studies showed severe axonal sensory-motor neuropathy superimposed by multiple mononeuropathies. Laboratory investigations were remarkable for biclonal gammopathy of IgM kappa, IgA lambda and severe sudomotor and mild cardiovagal autonomic dysfunction. A right sural nerve biopsy showed multifocal axonal neuropathy, prominent microvasculitis, and prominent large endoneurial deposits of Congo-red negative amorphous material. Laser dissected mass spectrometry-based proteomics identified IgM kappa deposit without serum amyloid-P protein. This case has several distinctive features, including motor preceding sensory involvement, prominent IgM-kappa proteinaceous deposits replacing most of the endoneurium, a prominent inflammatory component, and improvement of motor strength after immunotherapy.

TS-HDS autoantibody: clinical characterization and utility from real-world tertiary care center experience.

OBJECTIVES: To evaluate clinical utility of trisulfated-heparin disaccharide (TS-HDS) IgM testing from real-world tertiary care center experience. METHODS: Medical records of patients with positive TS-HDS antibodies who were evaluated at Mayo Clinic from 2009 to 2022 were reviewed. RESULTS: Seventy-seven patients (50 females) had positive TS-HDS antibody. Median age was 48 (9-77) years. Median titer was 25,000 (range 11,000-350,000). Twenty-six patients (34%) did not have objective evidence of peripheral neuropathy. Nine patients (12%) had other known causes of neuropathy. Among the remaining 42 patients, half presented with subacute progressive course; the other half had chronic indolent course. Most common phenotypes were length-dependent peripheral neuropathy (n = 20, 48%), length-dependent small-fiber neuropathy (n = 11, 26%), and non-length-dependent small-fiber neuropathy (n = 7, 17%). Nerve biopsies showed epineurial inflammatory cell collections in 2 but no interstitial abnormalities in the remaining 7. The majority of intraepidermal nerve fiber densities (7/10), thermoregulatory sweat tests (12/21) and autonomic reflex screens (27/49) were normal. Post-immunotherapy improvement in mRS/INCAT disability score/pain was only seen in 13/42 (31%) TS-HDS IgM positive patients. Patients presenting with sensory ganglionopathy, non-length dependent small-fiber neuropathy, or subacute progressive neuropathy with and without TS-HDS antibody responded similarly to immunotherapy (40% vs 80%, p = 0.30). DISCUSSION: TS-HDS IgM has limited phenotypic or disease specificity; it was found to be positive among patients with various neuropathy phenotypes as well as patients without objective evidence of neuropathy. Clinical improvement with immunotherapy, although was observed in a small proportion of TS-HDS IgM seropositive patients, was not more frequent when compared to seronegative patients with similar presentations.

Nerve transcriptomes in autoimmune and genetic demyelinating neuropathies: Pathogenic pathway assessment of nerve demyelination.

The pathogenesis of autoimmune demyelinating neuropathies is poorly understood compared to inherited demyelinating forms. We performed whole transcriptome (RNA-Seq) using nerve biopsy tissues of patients with different autoimmune and inherited demyelinating neuropathies (CIDP n = 10, POEMS n = 18, DADS n = 3, CMT1 n = 3) versus healthy controls (n = 6). A limited number of differentially expressed genes compared to healthy controls were identified (POEMS = 125, DADS = 15, CMT = 14, CIDP = 5). Divergent pathogenic pathways including inflammatory, demyelinating and neurite regeneration such as with the triggering receptor expressed on myeloid cells (TREM1) part of the immunoglobulin superfamily and RhoGD1 are found. Shared and discordant pathogenic injury are discovered between autoimmune and inherited forms.

Standardized Autonomic Testing in Patients With Probable Radiation-Induced Afferent Baroreflex Failure.

Injury of the afferent limb of the baroreflex from neck radiation causes radiation-induced afferent baroreflex failure (R-ABF). Identification and management of R-ABF is challenging. We aimed to investigate the pattern of autonomic dysfunction on standardized autonomic testing in patients with probable R-ABF. We retrospectively analyzed all autonomic reflex screens performed at Mayo Clinic in Rochester, MN, between 2000 and 2020 in patients with probable R-ABF. Additional tests reviewed included ambulatory blood pressure monitoring, plasma norepinephrine, and thermoregulatory sweat test. We identified 90 patients with probable R-ABF. Median total composite autonomic severity score (range, 0-10) was 7 (interquartile range, 6-7). Cardiovascular adrenergic impairment was seen in 85 patients (94.4%), increased blood pressure recovery time after Valsalva maneuver in 71 patients (78.9%; median 17.4 seconds), and orthostatic hypotension in 68 patients (75.6%). Cardiovagal impairment was demonstrated by abnormal heart rate responses to deep breathing (79.5%), Valsalva ratio (87.2%), and vagal baroreflex sensitivity (57.9%). Plasma norepinephrine was elevated and rose appropriately upon standing (722-1207 pg/mL). Ambulatory blood pressure monitoring revealed hypertension, postural hypotension, hypertensive surges, tachycardia, and absence of nocturnal dipping. Blood pressure lability correlated with impaired vagal baroreflex function. Postganglionic sympathetic sudomotor function was normal in most cases; the most frequent thermoregulatory sweat test finding was focal neck anhidrosis (78.9%). Standardized autonomic testing in R-ABF demonstrates cardiovascular adrenergic impairment with orthostatic hypotension, blood pressure lability, and elevated plasma norepinephrine. Cardiovagal impairment is common, while sudomotor deficits are limited to direct radiation effects.

Clinical presentation and autonomic profile in Ross syndrome.

BACKGROUND: Ross syndrome is a rare disorder characterized by tonic pupils, hyporeflexia, and segmental anhidrosis. We sought to characterize the clinical presentation, associated autoimmune disorders, and autonomic profile in patients with Ross syndrome to further elucidate its pathophysiology. METHODS: We performed a retrospective chart review of all patients who underwent a thermoregulatory sweat test (TST) between 1998 and 2020 and had confirmation of the diagnosis of Ross syndrome by an autonomic disorders specialist. Standardized autonomic reflex testing was reviewed when available. RESULTS: Twenty-six patients with Ross syndrome were identified. The most common initial reported manifestation was an abnormal segmental sweating response in 16 patients (described as hyperhidrosis in 12 patients and anhidrosis in 4 patients) while a tonic pupil was the initial manifestation in 10 patients. Other commonly reported symptoms included fatigue, chronic cough, and increased urinary frequency. An associated autoimmune disorder was identified in one patient. Positive autoantibodies were found in a minority of patients often with unclear clinical significance. Distributions of anhidrosis encountered were segmental (n = 15), widespread (n = 7), and global (n = 4). Well-circumscribed small areas of preserved sweating within areas of anhidrosis were observed in the majority of patients (88.5%). Anhidrosis progressed slowly over time and sudomotor dysfunction was predominantly (post)ganglionic. Cardiovagal and adrenergic functions were preserved in most patients. CONCLUSIONS: The pattern of autonomic dysfunction in Ross syndrome is suggestive of a limited autonomic ganglioneuropathy. Sudomotor impairment is prominent and should be the focus of symptomatic management; however, clinicians should be aware of symptoms beyond the classic triad.

Pure Motor Onset and IgM-Gammopathy Occurrence in Multifocal Acquired Demyelinating Sensory and Motor Neuropathy.

OBJECTIVES: To longitudinally investigate patients with multifocal acquired demyelinating sensory and motor (MADSAM) neuropathy, quantifying timing and location of sensory involvements in motor-onset patients, along with clinico-histopathological and electrophysiological findings to ascertain differences in patients with and without monoclonal gammopathy of uncertain significance (MGUS). METHODS: Patients with MADSAM neuropathy seen at Mayo Clinic and tested for monoclonal gammopathy and ganglioside antibodies, were retrospectively reviewed (January 1st, 2007-December 31st, 2018). RESULTS: Of 76 patients with MADSAM, 53% had pure motor, 16% pure sensory, 30% sensorimotor and 1% cranial nerve onsets. Motor-onset patients were initially diagnosed as multifocal motor neuropathy (MMN). MGUS occurred in 25% (89% IgM subtype), associating with ganglioside autoantibodies (p<0.001) and higher IgM titers (p<0.04). Median time to sensory involvements (confirmed by electrophysiology) in motor-onset patients was 18 months (range: 6-180). Compared to initial motor nerve involvements, subsequent sensory findings were within the same territory 35% (14/40), outside 20% (8/40), or both 45% (18/40). Brachial and lumbosacral plexus MRI was abnormal in 87% (34/39) and 84% (21/25), respectively, identifying hypertrophy and increased T2 signal predominantly in brachial plexus trunks (64%), divisions (69%), and cords (69%), and intrapelvic sciatic (64%) and femoral (44%) nerves. Proximal fascicular nerve biopsies (n=9) more frequently demonstrated onion-bulb pathology (p=0.001) and endoneurial inflammation (p=0.01) than distal biopsies (n=17). MRI and biopsy findings were similar amongst patient subgroups. Initial Inflammatory Neuropathy Cause and Treatment (INCAT) disability scores were higher in patients with MGUS relative to without (p=0.02). Long-term treatment responsiveness by INCAT score reduction ≥1 or motor Neuropathy Impairment Score (mNIS) >8 point reduction occurred in 75% (49/65) irrespective of MGUS or motor-onsets. Most required ongoing immunotherapy (86%). Patients with MGUS more commonly required dual-agent immunotherapy for stability (p=0.02). DISCUSSION: Pure motor-onsets are the most common MADSAM presentation. Long-term follow-up, repeat electrophysiology and nerve pathology help distinguish motor-onset MADSAM from MMN. Better long-term immunotherapy responsiveness occurs in motor-onset MADSAM compared to MMN reports. Patients having MGUS commonly require dual immunotherapy. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that most clinical, electrophysiological, and histopathological findings were similar between patients with MADSAM with and without monoclonal gammopathy of unknown significance.

Natural History of Afferent Baroreflex Failure in Adults.

OBJECTIVE: To describe the natural history of afferent baroreflex failure (ABF) based on systematic review of clinical and laboratory data in patients with a diagnosis of ABF at Mayo Clinic Rochester. METHODS: We performed a retrospective chart review of all patients who underwent standardized autonomic reflex testing between 2000 and 2020 and had confirmation of the diagnosis of ABF by an autonomic disorders specialist. Patients were identified using a data repository of medical records. Variables included demographic, all-cause mortality, medications, ABF manifestations, comorbidities, and laboratory (autonomic testing, blood pressure monitoring, echocardiogram, brain imaging, plasma catecholamines, serum sodium level, and kidney function tests). RESULTS: A total of 104 patients with ABF were identified. Head and neck radiation was the most common etiology (86.5%), followed by neck surgery (5.8%) and other causes (7.7%). The most common findings were hypertension (87.5%), fluctuating blood pressure (78.8%), orthostatic hypotension (91.3%), syncope (58.6%), headache (22.1%), and tachycardia (20.2%). Patients commonly received antihypertensives (66.3%), pressor agents (41.3%), or a combination of both (19.2%). The median latency from completion of radiation to ABF was longer compared to the latency in the surgery group (p < 0.0001). Comorbidities, including complications from neck radiation, were frequently seen and all-cause mortality was 39.4% over a 20-year period. CONCLUSIONS: ABF should be suspected in patients with prior head and neck cancer treated by radiation or surgery who present with labile hypertension and orthostatic hypotension. Management may require both antihypertensive and pressor medications. The morbidity and mortality in ABF are high.

Neurofascin-155 Immunoglobulin Subtypes: Clinicopathologic Associations and Neurologic Outcomes.

BACKGROUND AND OBJECTIVE: Multiple studies highlighting the diagnostic utility of neurofascin-155 (NF155)-immunoglobulin G4 (IgG4) in chronic demyelinating inflammatory polyradiculoneuropathy (CIDP) have been published. However, few studies comprehensively address the long-term outcomes or clinical utility of NF155-immunoglobulin M (IgM) or NF155-immunoglobulin G (IgG) in the absence of NF155-IgG4. We evaluated phenotypic and histopathologic specificity and differences in outcomes between these NF155 antibody isotypes or IgG subclasses. We also compare NF155-IgG4-seropositive cases to other seropositive demyelinating neuropathies. METHODS: Neuropathy patient sera at Mayo Clinic were tested for NF155-IgG4, NF155-IgG, and NF155-IgM autoantibodies. Demographic and clinical data of all seropositive cases were reviewed. RESULTS: We identified 32 NF155 cases (25 NF155-IgG-positive [20 NF155-IgG4-positive], 7 NF155-IgM-seropositive). NF155-IgG4-seropositive patients clinically presented with distal more than proximal muscle weakness, positive sensory symptoms (prickling, asymmetric paresthesia, neuropathic pain), and gait ataxia. Cranial nerve involvement (11/20 [55%]) and papilledema (4/12 [33%]) occurred in many. Electrodiagnostic testing (EDX) demonstrated demyelinating polyradiculoneuropathy (19/20 [95%]). Autonomic involvement occurred in 45% (n = 9, median composite autonomic scoring scale score 3.5, range 1-7). Nerve biopsies from the NF155-IgG4 patients (n = 11) demonstrated grouped segmental demyelination (50%), myelin reduplication (45%), and paranodal swellings (50%). Most patients needed second- and third-line immunosuppression but had favorable long-term outcomes (n = 18). Among 14 patients with serial EDX over 2 years, all except one demonstrated improvement after treatment. NF155-IgG-positive, NF155-IgG4-negative (NF155-IgG-positive) and NF155-IgM-positive patients were phenotypically different from NF155-IgG4-seropositive patients. Sensory ataxia, neuropathic pain, cerebellar dysfunction, and root/plexus MRI abnormalities were significantly more common in NF155-IgG4-positive compared to myelin-associated glycoprotein (MAG)-IgM neuropathy. Chronic immune sensory polyradiculopathy (CISP)/CISP-plus phenotype was more common among contactin-1 neuropathies compared to NF155-IgG4-positive cases. NF155-IgG4-positive cases responded favorably to immunotherapy compared to MAG-IgM-seropositive cases with distal acquired demyelinating symmetric neuropathy (p < 0.001) and had better long-term clinical outcomes compared to contactin-1 IgG (p = 0.04). DISCUSSION: We report long-term follow-up and clinical outcome of NF155-IgG4 cases. NF155-IgG4 but not IgM or IgG cases have unique clinical-electrodiagnostic signature. We demonstrate NF155-IgG4-positive patients, unlike classical CIDP with neuropathic pain and dysautonomia common at presentation. Long-term outcomes were favorable. CLASSIFICATION OF EVIDENCE: This study provides Class III evidence that NF155-IgG4-seropositive patients, compared to patients with typical CIDP, present with distal more than proximal muscle weakness, positive sensory symptoms, and gait ataxia.

Small Fiber Neuropathy Incidence, Prevalence, Longitudinal Impairments, and Disability.

BACKGROUND AND OBJECTIVES: There are limited population-based data on small fiber neuropathy (SFN). We wished to determine SFN incidence, prevalence, comorbid conditions, longitudinal impairments, and disabilities. METHODS: Test-confirmed patients with SFN in Olmsted, Minnesota, and adjacent counties were compared 3:1 to matched controls (January 1, 1998-December 31, 2017). RESULTS: Ninety-four patients with SFN were identified, with an incidence of 1.3/100,000/y that increased over the study period and a prevalence of 13.3 per 100,000. Average follow-up was 6.1 years (0.7-43 years), and mean onset age was 54 years (range 14-83 years). Female sex (67%), obesity (body mass index mean 30.4 vs 28.5 kg/m2), insomnia (86% vs 54%), analgesic-opioid prescriptions (72% vs 46%), hypertriglyceridemia (180 mg/dL mean vs 147 mg/dL), and diabetes (51% vs 22%, p < 0.001) were more common (odds ratio 3.8-9.0, all p < 0.03). Patients with SFN did not self-identify as disabled with a median modified Rankin Scale score of 1.0 (range 0-6) vs 0.0 (0-6) for controls (p = 0.04). Higher Charlson comorbid conditions (median 6, range 3-9) occurred vs controls (median 3, range 1-9, p < 0.001). Myocardial infarctions occurred in 46% vs 27% of controls (p < 0.0001). Classifications included idiopathic (70%); diabetes (15%); Sjögren disease (2%); AL-amyloid (1%); transthyretin-amyloid (1%); Fabry disease (1%); lupus (1%); postviral (1%); Lewy body (1%), and multifactorial (5%). Foot ulcers occurred in 17, with 71% having diabetes. Large fiber neuropathy developed in 36%, on average 5.3 years (range 0.2-14.3 years) from SFN onset. Median onset Composite Autonomic Severity Score (CASS) was 3 (change per year 0.08, range 0-2.0). Median Neuropathy Impairment Scale (NIS) score was 2 at onset (range 0-8, change per year 1.0, range -7.9 to +23.3). NIS score and CASS change >1 point per year occurred in only AL-amyloid, hereditary transthyretin-amyloid, Fabry, uncontrolled diabetes, and Lewy body. Death after symptom onset was higher in patients with SFN (19%) vs controls (12%, p < 0.001), 50% secondary to diabetes complications. DISCUSSION: Isolated SFN is uncommon but increasing in incidence. Most patients do not develop major neurologic impairments and disability but have multiple comorbid conditions, including cardiovascular ischemic events, and increased mortality from SFN onsets. Development of large fiber involvements and diabetes are common over time. Targeted testing facilitates interventional therapies for diabetes but also rheumatologic and rare genetic forms.

Predicting phenoconversion in pure autonomic failure.

OBJECTIVE: To determine predicting factors and frequency of phenoconversion from pure autonomic failure (PAF) into a synucleinopathy with motor or cognitive involvement of multiple system atrophy (MSA), Parkinson disease (PD), or dementia with Lewy bodies (DLB). METHODS: We performed a retrospective review of all patients with PAF from 2001 to 2011 evaluated at Mayo Clinic, Rochester. Clinical follow-up and patient telephone calls were used to assess for development of symptoms and diagnosis of MSA, PD, or DLB. Clinical and laboratory variables were extracted with factors predictive of evolution assessed using group comparison, odds ratio, and logistical regression. RESULTS: Among 275 patients with PAF at presentation, 67 (24%) phenoconverted to a synucleinopathy with motor or cognitive involvement; 34 met criteria for MSA, while 33 met criteria for PD or DLB. Age at onset was younger in MSA phenoconverters. Clinical features at presentation influenced phenoconversion: severe bladder symptoms were more common in MSA phenoconverters; subtle motor signs were more frequent in MSA and PD/DLB phenoconverters. MSA phenoconverters were more likely to have higher supine norepinephrine levels and preganglionic pattern of anhidrosis. Presentation variables predicting MSA phenoconversion included subtle motor signs, supine norepinephrine levels, severe bladder symptoms, and dream enactment behavior. Presentation variables predictive of PD/DLB phenoconversion included subtle motor signs, dream enactment behavior, and constipation. CONCLUSIONS: Our findings suggest that at least a quarter of patients with PAF phenoconvert to MSA, PD, or DLB. Presentation features determine patients at risk for evolution with specific patterns indicative of phenoconversion to MSA vs PD/DLB. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that several presentation variables including subtle motor signs, severe bladder symptoms, and dream enactment behavior are associated with an increased risk of developing a synucleinopathy with motor or cognitive involvement.

Elimination of spurious absent sweat response in QSWEAT recordings.

INTRODUCTION: Forearm QSWEAT recordings are occasionally absent in females, likely due to high skin resistance. METHODS: We identified consecutive subjects with no sudomotor abnormalities but absent/markedly reduced QSWEAT forearm volume, and repeated QSWEAT at the same site after gentle abrasion. RESULTS: QSWEAT volumes were absent for 4 subjects and markedly reduced for the other 4 (median 0.01, IQR 0-0.03). After gentle skin abrasion, repeat volumes were significantly higher for all subjects and became normal in 7 of 8 subjects. DISCUSSION: Skin abrasion restores QSWEAT volumes in previously absent/markedly reduced site suggesting that skin preparation using abrasion is more effective.

Pure autonomic failure: Predictors of conversion to clinical CNS involvement.

OBJECTIVE: Based on the observation that a subset of patients originally diagnosed with pure autonomic failure (PAF) eventually develops extrapyramidal or cerebellar involvement consistent with multiple system atrophy (MSA), Parkinson disease (PD), or dementia with Lewy bodies (DLB), we aimed to identify predictors of progression of PAF to more sinister synucleinopathies. METHODS: In this retrospective cohort study, we reviewed patients seen at Mayo Clinic Rochester by autonomic specialists between 2001 and 2011 and during initial evaluation diagnosed with orthostatic hypotension consistent with PAF (possible PAF). In order to assess for the presence or absence of progression, we identified patients with 3 years or more of in-person follow-up (stable PAF) or documented progression to another synucleinopathy (converters). To identify predictors of conversion, we assessed odds of conversion based on clinical, autonomic, and laboratory variables. RESULTS: Among 318 patients fulfilling criteria for possible PAF, we identified 41 with stable PAF and 37 (12%) converters. Of those who evolved, 22 developed MSA, 11 developed PD/DLB, and 4 remained indeterminate. Several variables were identified to predict conversion to MSA: (1) mild degree of cardiovagal impairment, (2) preganglionic pattern of sweat loss, (3) severe bladder dysfunction, (4) supine norepinephrine >100 pg/mL, and (5) subtle motor signs at first presentation. Separate variables were found to predict conversion to PD/DLB. Composite conversion scores were generated based on individual predictors. CONCLUSIONS: Over 10% of patients originally diagnosed with PAF eventually evolve to develop CNS involvement, most commonly MSA. A combination of variables allows for prediction of conversion.

Chronic meralgia paresthetica and neurectomy: a clinical pathologic study.

OBJECTIVE: To understand the pathologic and clinical correlates of patients with chronic meralgia paresthetica (MP) undergoing lateral femoral cutaneous nerve (LFCN) neurectomy. METHODS: A retrospective cohort approach was utilized to identify 7 patients undergoing LFCN neurectomy for intractable pain. Control autopsied LFCN was obtained. Clinical, radiologic, and electrophysiologic features were reviewed. RESULTS: In identified cases, preoperative symptoms included severe lateral thigh pain and numbness. The duration of symptoms prior to surgery ranged from 2 to 15 years. Body mass index (BMI) varied from 20 kg/m(2) to 44.8 kg/m(2) (normal-morbidly obese), with 6 out of 7 patients being obese. No patients were diabetic. Focal nerve indentation at the inguinal ligament was seen intraoperatively and on gross pathology in 4 of 7 cases. Multifocal fiber loss, selective loss of large myelinated fibers, thinly myelinated profiles, regenerating nerve clusters, perineurial thickening, and subperineurial edema were seen. None of these features were observed in control nerve. Morphometric analysis confirmed loss of large myelinated fibers with small and intermediate size fiber predominance. Five patients had varying degrees of intraneural and epineurial inflammation. Six of 7 reported improved pain after neurectomy, sometimes dramatic. CONCLUSIONS: Patients with chronic MP and intractable pain have an LFCN mononeuropathy with loss of nerve fibers. Pathologic and clinical study supports a compressive pathogenesis as the primary mechanism. Abnormal nerve inflammation coexists and may play a role in pathogenesis. These selected patients typically benefited from neurectomy at a site of inguinal ligament compression. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that patients with chronic MP LFCN neurectomy experience improvement in MP-related pain.