BACKGROUND: Gabapentin, a widely prescribed medication for various neuropathic pain conditions, has demonstrated efficacy in managing diverse neurological disorders. While conventional side effects are well-documented, a growing body of evidence suggests the existence of atypical side effects, necessitating comprehensive exploration. This paper aims to systematically review and summarize the literature on the atypical side effects of gabapentin, shedding light on manifestations beyond the conventional spectrum.
METHODS: A systematic review was conducted, encompassing peer-reviewed articles published up to the knowledge cutoff date in November 2023. Databases, specifically PubMed, were searched for relevant studies, focusing on atypical side effects such as myoclonus, ataxia, pediatric aggression, respiratory depression, pneumonia, pregnancy complications, sleep interference, encephalopathy, peripheral edema, suicidal ideation, dyskinesia, anorgasmia, and myopathy. Inclusion criteria comprised studies with a focus on gabapentin-related atypical side effects, published in recognized journals and involving human subjects.
RESULTS: The review identified a spectrum of atypical side effects associated with gabapentin use, ranging from neurological manifestations like myoclonus and ataxia to behavioral changes such as pediatric aggression and suicidal ideation. Additionally, respiratory complications, pregnancy-related issues, sleep disturbances, and rare complications like encephalopathy and myopathy were observed. Literature synthesis provided insights into the incidence, clinical presentation, and potential mechanisms underlying these atypical side effects.
CONCLUSIONS: This comprehensive review highlights the diverse range of atypical side effects associated with gabapentin use, expanding beyond conventional knowledge. Healthcare practitioners must be cognizant of these manifestations, recognizing their potential impact on patient well-being. As clinical decision-making relies on a thorough understanding of a medication\'s side effect profile, this review contributes to enhancing awareness and fostering informed practices in the prescription and management of gabapentin. Further research is warranted to elucidate the mechanisms and risk factors associated with these atypical side effects, refining our understanding of gabapentin\'s safety profile.

Peripheral and autonomic neuropathy are common disease manifestations in systemic amyloidosis. The neurofilament light chain (NfL), a neuron-specific biomarker, is released into the blood and cerebrospinal fluid after neuronal damage. There is a need for an early and sensitive blood biomarker for polyneuropathy, and this systematic review provides an overview on the value of NfL in the early detection of neuropathy, central nervous system involvement, the monitoring of neuropathy progression, and treatment effects in systemic amyloidosis. A literature search in PubMed, Embase, and Web of Science was performed on 14 February 2024 for studies investigating NfL levels in patients with systemic amyloidosis and transthyretin gene-variant (TTRv) carriers. Only studies containing original data were included. Included were thirteen full-text articles and five abstracts describing 1604 participants: 298 controls and 1306 TTRv carriers or patients with or without polyneuropathy. Patients with polyneuropathy demonstrated higher NfL levels compared to healthy controls and asymptomatic carriers. Disease onset was marked by rising NfL levels. Following the initiation of transthyretin gene-silencer treatment, NfL levels decreased and remained stable over an extended period. NfL is not an outcome biomarker, but an early and sensitive disease-process biomarker for neuropathy in systemic amyloidosis. Therefore, NfL has the potential to be used for the early detection of neuropathy, monitoring treatment effects, and monitoring disease progression in patients with systemic amyloidosis.

Neurofilament light protein (NfL) is a part of the neuronal skeleton, primarily expressed in axons, and is released when nerves are damaged. NfL has been found to be a potential diagnostic biomarker in different types of polyneuropathies. However, whether NfL levels can be used as a predictor for the risk of disease progression is currently less understood. We searched MEDLINE (PubMed), Embase, Cochrane Library, and Web of Science Searches and included longitudinal studies with a baseline and follow-up examination of adult patients with polyneuropathy and NfL measured in blood. Twenty studies investigating NfL as a predictor of disease progression were identified, examining eight polyneuropathy subtypes. The results from studies in Chronic Inflammatory Demyelinating Polyneuropathy (CIDP) patients were divergent, with two out of five studies finding a significant association between NfL levels and clinical outcomes. Meta-analysis of the three Guillian-Barré Syndrome (GBS) studies found higher odds for the inability to run after 1 year in patients with high levels of NfL (odds ratio 2.18, 95% confidence interval 1.04-4.56). Results from studies examining other subacute or chronic polyneuropathies like Charcot-Marie-Tooth (CMT) varied in study design and results. Our findings suggest NfL can be used as a predictor of disease progression, particularly in polyneuropathies such as CIDP and GBS. However, NfL may not serve as a reliable and cost-effective biomarker for slowly progressive polyneuropathies like CMT. Future standardized studies considering NfL as a prognostic blood biomarker in patients with different types of polyneuropathies are warranted.

Amyloidoses represent a group of diseases characterized by the pathological accumulation in the extracellular area of insoluble misfolded protein material called \"amyloid\". The damage to the tissue organization and the direct toxicity of the amyloidogenic substrates induce progressive dysfunctions in the organs involved. They are usually multisystem diseases involving several vital organs, such as the peripheral nerves, heart, kidneys, gastrointestinal tract, liver, skin, and eyes. Transthyretin amyloidosis (ATTR) is related to abnormalities of transthyretin (TTR), a protein that acts as a transporter of thyroxine and retinol and is produced predominantly in the liver. ATTR is classified as hereditary (ATTRv) and wild type (ATTRwt). ATTRv is a severe systemic disease of adults caused by mutations in the TTR gene and transmitted in an autosomal dominant manner with incomplete penetrance. Some pathogenic variants in TTR are preferentially associated with a neurological phenotype (progressive peripheral sensorimotor polyneuropathy); others are more frequently associated with restrictive heart failure. However, many mutations express a mixed phenotype with neurological and cardiological involvement. ATTRv is now a treatable disease. A timely and definite diagnosis is essential in view of the availability of effective therapies that have revolutionized the management of affected patients. The purpose of this review is to familiarize the clinician with the disease and with the correct diagnostic pathways in order to obtain an early diagnosis and, consequently, the possibility of an adequate treatment.

Diabetes Mellitus is a public health problem associated with complications such as neuropathy; however, it has been proposed that these may begin to develop during prediabetes and may also be present in persons with obesity. Diabetic peripheral neuropathy is the presence of signs and/or symptoms of peripheral nerve dysfunction in people living with diabetes, which increases the risk of developing complications and has a deleterious impact on quality of life. As part of the therapeutic protocol for diabetes, screening tests to identify peripheral neuropathy are suggested, however, there are no recommendations for people with prediabetes and obesity without symptoms such as pain, numbness, or paresthesias. Moreover, clinical screening tests that are usually used to recognize this alteration, such as tendon reflex, temperature sensation, and pressure and vibration perception, might be subjective as they depend on the evaluator\'s experience thus the incorrect application of these tests may not recognize the damage to small or large-nerve fibers. Recent evidence suggests that an objective study such as the impairment of the rate-dependent depression of the H-reflex could be used as a biomarker of spinal disinhibition and hence may provide more information on sensorimotor integration.

Introduction: Polyneuropathy (PNP) is a chronic progressive disease that over time can lead to damage of sensory, motor and/or autonomic peripheral nerves. Symptoms vary from predominantly sensory to severe sensorimotor affection both proximally and distally. This can result in considerable functional impairments that affect activities of daily living. In other neurological patients, strength training has shown to improve strength and functional outcomes. Since medical treatment only exists for very few percentages of the underlying causes it is obvious to consider if strength training could be a potential treatment for functional impairments. To date little is known on the effect of strength training in patients with PNP. Aim: The aim of this scoping review was to summarize research on strength training and outcomes on physical function in patients with PNP. Methods: We systematically searched five data bases; Pubmed, Embase, Cinahl, Cochrane library and Web of science. Studies on strength training (load ≥70% of 1RM) in patients with PNP were included. The search was carried out in November 2022. Results: 362 articles were screened by title and abstract, 101 articles were full text screened. Eight studies were included. Patients with Charcot-Marie-Tooth (CMT), chronic inflammatory polyneuropathy (CIDP) and diabetic polyneuropathy (DPN) were represented in the studies (five RCTs, two case-series, and one cross-over trial). The methodological quality ranged from fair-poor in seven studies, one study reached good quality. Results from the studies indicated that strength training in CMT, CIDP and DPN may improve strength. However, various outcomes were used to evaluate strength training, so direct comparisons were difficult. Discussion: In this scoping review we summarized research on strength training and outcomes evaluated in interventions in patients with PNP. Eight studies were included, they indicated that strength training may be beneficial for patients with PNP. However, due to low methodological strength of most studies a recommendation for patients with PNP cannot be made. Thus, the low number of studies with relatively low quality, where various functional outcomes were used, underscores the importance of future studies to evaluate the effect of strength training on relevant functional outcomes and strength in patients with PNP.

Nitrous oxide abuse can have detrimental effects on the central and peripheral nervous systems. This case study report aims to demonstrate a combination of severe generalized sensorimotor polyneuropathy and cervical myelopathy related to vitamin B12 deficiency following nitrous oxide abuse. We present a clinical case study and literature review examining primary research-published between 2012 and 2022-reporting nitrous oxide abuse affecting the spinal cord (myelopathy) and peripheral nerves (polyneuropathy); 35 articles were included in the review with a total of 96 patients, where the mean \"patients\" age was 23.9 years and were in a 2:1 male/female ratio. Of the 96 cases, within the review, 56% of patients were diagnosed with polyneuropathy, most commonly impacting the nerves of the lower limb (62%), while 70% of patients were diagnosed with myelopathy, most commonly impacting the cervical region (78%) on the spinal cord. In our clinical case study, a 28-year-old male underwent a multitude of diagnostic investigations for bilateral \"foot drop\" and sense of lower limb stiffness as ongoing complications of a vitamin B12 deficiency secondary to recreational nitrous oxide abuse. Both the literature review and our case report emphasize the dangers of recreational nitrous oxide inhalation, colloquially termed \"nanging\" and the risks it presents to both the central and peripheral nervous systems, which is erroneously considered by many recreational drug users to be less harmful than other illicit substances.

BACKGROUND: In 2014, we first described novel autoantibodies to the inositol 1,4,5-trisphosphate receptor type 1 (ITPR1-IgG/anti-Sj) in patients with autoimmune cerebellar ataxia (ACA) in this journal. Here, we provide a review of the available literature on ITPR1-IgG/anti-Sj, covering clinical and paraclinical presentation, tumour association, serological findings, and immunopathogenesis.
METHODS: Review of the peer-reviewed and PubMed-listed English language literature on ITPR1-IgG/anti-Sj. In addition, we provide an illustrative report on a new patient with ITPR1-IgG-associated encephalitis with cognitive decline and psychosis.
RESULTS: So far, at least 31 patients with serum ITPR1-IgG/anti-Sj have been identified (clinical information available for 21). The most common manifestations were ACA, encephalopathy with seizures, myelopathy, and (radiculo)neuropathy, including autonomic neuropathy. In 45% of cases, an underlying tumour was present, making the condition a facultative paraneoplastic neurological disorder. The neurological syndrome preceded tumour diagnosis in all but one case. In most cases, immunotherapy had only moderate or no effect. The association of ITPR1-IgG/anti-Sj with manifestations other than ACA is corroborated by the case of a 48-year-old woman with high-titre ITPR1-IgG/anti-Sj antibodies and rapid cognitive decline, affecting memory, attention and executive function, and psychotic manifestations, including hallucinations, investigated here in detail. FDG-PET revealed right-temporal glucose hypermetabolism compatible with limbic encephalitis. Interestingly, ITPR1-IgG/anti-Sj mainly belonged to the IgG2 subclass in both serum and cerebrospinal fluid (CSF) in this and further patients, while it was predominantly IgG1 in other patients, including those with more severe outcome, and remained detectable over the entire course of disease. Immunotherapy with intravenous methylprednisolone, plasma exchange, and intravenous immunoglobulins, was repeatedly followed by partial or complete recovery. Long-term treatment with cyclophosphamide was paralleled by relative stabilization, although the patient noted clinical worsening at the end of each treatment cycle.
CONCLUSIONS: The spectrum of neurological manifestations associated with ITPR1 autoimmunity is broader than initially thought. Immunotherapy may be effective in some cases. Studies evaluating the frequency of ITPR1-IgG/anti-Sj in patients with cognitive decline and/or psychosis of unknown aetiology are warranted. Tumour screening is essential in patients presenting with ITPR1-IgG/anti-Sj.

UNASSIGNED: Adenopathy and extensive skin patch overlying plasmacytoma syndrome is a paraneoplastic syndrome characterized by a cutaneous vascular patch overlying a plasmacytoma and systemic manifestations. It is thought to be an early stage of polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes syndrome, which is a rare, but potentially fatal multisystemic disease that is associated with plasma cell dyscrasia. Thus, a high index of suspicion is required to identify patients with adenopathy and extensive skin patch overlying plasmacytoma as they may present with early polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes, which is curable if detected early.
UNASSIGNED: To report additional cases of adenopathy and extensive skin patch overlying plasmacytoma syndrome, describe dermatoscopic and histologic findings of the cutaneous patch and review all up to date literature on adenopathy and extensive skin patch overlying plasmacytoma syndrome.
UNASSIGNED: Case series from a single tertiary care center.
UNASSIGNED: Here, we present the second case series of three patients with adenopathy and extensive skin patch overlying plasmacytoma syndrome who all meet the diagnostic criteria for polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes. The diagnosis was suspected based on the presence of the violaceous cutaneous patch along with symptoms of systemic involvement (fatigue, weight loss, weakness). Dermoscopy revealing regular dilated parallel capillaries was suggestive of a benign/reactive vascular process. Histopathology in all three cases showed reactive vascular proliferation with a characteristic 90° branching. To date only 20 cases of adenopathy and extensive skin patch overlying plasmacytoma have been published, including ours. All patients presented with cutaneous lesions (violaceous patch and others) and most, at least 15/20, met the diagnostic criteria for polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes. When clinical follow-up was reported, most patients had a favorable prognosis with partial or complete symptom resolution following treatment of the underlying plasmocytoma.

Guillain-Barré syndrome (GBS) is the most frequent cause of acute flaccid paralysis and if not diagnosed and treated timely, a significant cause of long-term disability. Incidence in Latin America ranges from 0.71 to 7.63 cases/100,000 person-years. Historically, GBS has been linked to infections (mainly gastrointestinal by Campylobacter jejuni) and vaccines (including those against severe acute respiratory syndrome coronavirus 2 [SARS-CoV-2]); however, a trigger cannot be detected in most cases. Regarding SARS-CoV-2, epidemiological studies have found no association with its development. Acute motor axonal neuropathy is the most common electrophysiological variant in Mexico and Asian countries. Intravenous immunoglobulin or plasma exchanges are still the treatment cornerstones. Mortality in Mexico can be as high as 12%. Avances in understanding the drivers of nerve injury in GBS that may provide the basis for developing targeted therapies have been made during the past decade; despite them, accurate criteria for selecting patients requiring acute treatment, prognostic biomarkers, and novel therapies are still needed. The newly-developed vaccines against SARS-CoV-2 have raised concerns regarding the potential risk for developing GBS. In the midst of coronavirus disease 2019 and vaccination campaigns against SARS-CoV-2, this review discusses the epidemiology, clinical presentation, management, and outcomes of GBS in Mexico.