CIDP mimics: a case series.

BACKGROUND: To report our experience with a group of patients referred for refractory CIDP who fulfilled "definite" electrodiagnostic EFNS criteria for CIDP but were found to have an alternate diagnosis. METHODS: Patients who were seen between 2017 and 2019 for refractory CIDP that fulfilled "definite" electrodiagnostic ENFS criteria for CIDP, but had an alternate diagnosis, were included. Patients who correctly had CIDP, anti MAG neuropathy, or MMN with conduction block, were excluded from the study. Demographics, clinical and electrophysiological characteristics, pertinent workup, final alternate diagnoses, and outcomes were collected. RESULTS: Seven patients were included: POEMS (n = 5), CANOMAD (n = 1), and neurolymphomatosis (n = 1). Most patients reported neuropathic pain and leg swelling (n = 6) or significant weight loss (n = 4). All patients had a monoclonal protein, and most patients who were tested had an elevated VEGF and CSF cyto-albuminologic dissociation. Electrophysiology showed pronounced intermediate more than distal demyelination, and axonal loss in the lower extremities. Response to steroids or IVIG varied, but some patients did respond to these treatments, especially early in the disease. CONCLUSION: Pain, systemic symptoms, suggestive electrophysiological findings, and/or a serum monoclonal protein should raise suspicion for CIDP mimics. Initial response to steroids or IVIG, over reliance on CSF, and electrophysiology findings can all be misleading.

Screening for genetic mutations in patients with neuropathy without definite etiology is useful.

OBJECTIVE: To determine the clinical usefulness of systemic genetic testing in neuropathies without definite etiology. METHODS: We systematically performed genetic testing in all patients with neuropathy who did not have a definite etiology, seen at our neuromuscular clinic between 2017 and 2020. The testing consisted of an inherited neuropathy panel (72-81 genes), which used next-generation sequencing technology. RESULTS: We screened 200 patients. Pathogenic mutations were found in 30 (15%). PMP22, TTR and GJB1, accounted for 83.3% of positive mutations. The management was altered in four patients (2%). Two patients were found to have hereditary transthyretin amyloidosis and were started on TTR gene silencers. Two patients were being treated for demyelinating autoimmune neuropathy and were diagnosed with CMT1A and CMTX. CONCLUSION: Screening for genetic mutations in patients with neuropathy without a definite etiology is useful. While only a minority of patients with unsuspected inherited neuropathy tested positive, the findings altered management in some, improving morbidity and, perhaps, mortality.

Nusinersen in adult patients with spinal muscular atrophy: Observations from a single center.

OBJECTIVE: To report our experience with adult patients with spinal muscular atrophy (SMA), some of whom were treated with nusinersen. METHODS: We reviewed charts of adult patients with SMA seen in our neuromuscular clinic between 2017 and 2019 and noted their demographics, clinical characteristics, treatment, and side effects. RESULTS: Twenty-two patients were included. Nine had type 2 and 13 type 3 SMA. Median age was 36 years (range 20-71). Most could not walk unassisted. Ten patients had significant respiratory impairment necessitating ventilation and 2 had tracheostomy. Seventeen had severe scoliosis. Ten patients were treated with nusinersen for 6-24 months (median 12 months), 3 of whom required bone laminectomy for intrathecal access. One developed bowel and bladder incontinence following the procedure. In the treated group, on average, % Medical Research Council change was 2.5% at 12 months and 3.9% at 24 months. Most untreated patients remained stable; 3 had slightly declined. Five treated patients reported subjective improvement. Treatment side effects included post lumbar puncture headache in 5 patients, 2 of whom needed blood patch, and 1 bacterial meningitis requiring inpatient treatment. Three patients stopped treatment after 12-24 months due to lack of improvement, recurrent pneumonia, or proteinuria. CONCLUSION: Side effects of nusinersen can be serious. Whereas half of treated patients reported modest improvement in function, there were no significant objective changes, which may point largely to a placebo effect. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that for some adult patients with SMA, nusinersen improves subjective function and causes serious adverse effects.

Diagnosis of paraproteinemic neuropathy: Room for improvement.

OBJECTIVE: To report our institutional experience with paraproteinemic neuropathy. METHODS: We reviewed the charts of patients evaluated at our tertiary, academic neuromuscular clinic for neuropathy between 2017 and 2019 and selected those with a serum monoclonal protein. We collected patients' characteristics and reviewed their initial diagnoses and eventual outcomes. RESULTS: Fifty-four of 410 patients with neuropathy (13%) had a monoclonal protein. Of these patients, 25% had not had SPEP or IFE checked prior to referral. FLC was not checked in any of the patients prior to referral. The neuropathy was felt to be related to the monoclonal protein in 24 patients (44%). Ten patients (19%), had been misdiagnosed either because they were not screened for monoclonal protein or the monoclonal protein was considered a MGUS. AL amyloid and POEMS syndrome were the most frequently missed diagnoses. CONCLUSION: The diagnosis of paraproteinemic neuropathy was missed in nearly one in five patients in our cohort. Failure to accurately characterize a paraproteinemic neuropathy can have devastating effect on patients as some have underlying malignancies. We propose that testing serum free light chains in patients with peripheral neuropathy of unknow etiology, when SPEP/IFE are normal, may reduce the rate of misdiagnosis. Furthermore, patients with refractory CIDP should be carefully screened for POEMS syndrome.

Safety signals mitigate the consequences of uncontrollable stress via a circuit involving the sensory insular cortex and bed nucleus of the stria terminalis.

BACKGROUND: Safety signals exert a powerful buffering effect when provided during exposure to uncontrollable stressors. We evaluated the role of the sensory insular cortex (Si) and the extend amygdala in this "safety signal effect." METHODS: Rats were implanted with microinjection cannula, exposed to inescapable tailshocks either with or without a safety signal, and later tested for anxiety-like behavior or neuronal Fos expression. RESULTS: Exposure to the uncontrollable stressor reduced later social exploration but not when safety signals were present. Temporary inhibition of Si during stressor exposure but not during later behavioral testing blocked the safety signal effect on social exploration. The stressor induced Fos in all regions of the amygdala, but safety signals significantly reduced the number of Fos immunoreactive cells in the basolateral amygdala and ventrolateral region of the bed nucleus of the stria terminalis (BNSTlv). Inhibition of BNSTlv neuronal activity during uncontrollable stressor exposure prevented the later reduction in social exploration. Finally, safety signals reduced the time spent freezing during uncontrollable stress. CONCLUSIONS: These data suggest that safety signals inhibit the neural fear or anxiety response that normally occurs during uncontrollable stressors and that inhibition of the BNSTlv is sufficient to prevent later anxiety. These data lend support to a growing body of evidence that chronic fear is mediated in the basolateral amygdala and BNSTlv and that environmental factors that modulate fear during stress will alter the long-term consequences of the stressor.

5-hydroxytryptamine 2C receptors in the basolateral amygdala are involved in the expression of anxiety after uncontrollable traumatic stress.

BACKGROUND: Exposure to uncontrollable stressors often increases anxiety-like behavior in both humans and rodents. In rat, this effect depends on stress-induced activity within the dorsal raphe nucleus (DRN). However, the role of serotonin in DRN projection regions is largely unknown. The goals of this study were to 1) assess the effect of uncontrollable stress on extracellular serotonin in the basolateral amygdala during the anxiety test, 2) determine whether DRN activity during a poststress anxiety test is involved in anxiety-like behavior, and 3) determine the role of the serotonin 2C receptor (5-HT(2C)) in uncontrollable stress-induced anxiety. METHOD: Rats were exposed to tail shocks that were either controllable or uncontrollable. On the following day, anxiety-like behavior was assessed in a Juvenile Social Exploration (JSE) test. Basolateral amygdala (BLA) extracellular serotonin concentrations were assessed during JSE by in vivo microdialysis 24 hours after uncontrollable stress, controllable stress, or no stress. In separate experiments, drugs were administered before the JSE test to inhibit the DRN or to block 5-HT(2C) receptors. RESULTS: Exposure to uncontrollable shock reduced later social exploration. Prior uncontrollable stress potentiated serotonin efflux in the BLA during social exploration, but controllable stress did not. Intra-DRN 8-OH-DPAT and systemic and intra-BLA 5-HT(2C) receptor antagonist SB 242,084 prevented the expression of potentiated anxiety in uncontrollably stressed rats. Intra-BLA injection of the 5-HT(2C) agonist CP 809,101 mimicked the effect of stress. CONCLUSIONS: These results suggest that the anxiety-like behavior observed after uncontrollable stress is mediated by exaggerated 5-HT acting at BLA 5-HT(2C) receptors.