Abstract
BackgroundDespite its initial association with sensory neuropathies, anti-fibroblast growth factor receptor 3 (FGFR3) antibodies have been since reported with a broad range of neuropathies and clinical features. The aim of the study is to report the clinical and electro diagnostic findings in a cohort of patients with sensory or sensorimotor polyneuropathy and anti-FGFR3 antibodies.MethodsWe performed a retrospective chart review to assess the clinical characteristics of patients with sensory or sensorimotor neuropathy related to FGFR3 antibodies. Descriptive statistics were reported using frequencies and percentages for categorical variables and median and interquartile range (IQR) for continuous variables.ResultsThis study included 14 patients (9 women) with a median age of 51.9 years (IQR 48–57). The most common presenting symptoms were painful paresthesia (100%), gait instability (42.9%), constitutional symptoms (42.9%), and autonomic symptoms (28.6%). Onset of symptoms was chronic (≥12 weeks) in eight patients (57.1%). Examination showed a distal loss of sensation to pin prick (100%), as well as impaired vibration sensation (78.6%) and proprioception (35.7%), in the distal extremities. We also observed mild weakness in the distal lower-extremities (42.9%). Three patients (21.4%) had trigeminal neuralgia, three patients (21.4%) had co-existing autoimmune disease, and one patient (7.1%) had a history of renal cell carcinoma. The mean titer of FGFR3 antibody was 14,285.71 (IQR 5000–16,750). All 14 patients produced normal results in the neuropathy workup. Nerve conduction study and electromyography showed sensory axonal neuropathy in four patients (28.6%), sensorimotor axonal neuropathy in seven patients (50%), and a normal result in three patients (21.4%). For those with a normal NCS/EMG, a skin biopsy showed a non-length-dependent small fiber neuropathy.ConclusionsNeuropathy related to FGFR3 antibodies can potentially involve small and large fibers, sensory and motor fibers, and even the trigeminal nerve, which contributes to a highly variable clinical presentation.
Highlights
Despite its initial association with sensory neuropathies, anti-fibroblast growth factor receptor 3 (FGFR3) antibodies have been since reported with a broad range of neuropathies and clinical features
Seven patients were lost to follow-up after two visits (1–3 month follow-up) and four patients were determined to have neuropathy that was not related to FGFR3 antibody
The broad spectrum of clinical features and EMG/Nerve conduction studies (NCS) results that are seen across multiple studies, including the current study, suggest that neuropathies associated with FGFR3 antibodies have the potential to involve small and large fibers, sensory and motor fibers, and the trigeminal nerve
Summary
Despite its initial association with sensory neuropathies, anti-fibroblast growth factor receptor 3 (FGFR3) antibodies have been since reported with a broad range of neuropathies and clinical features. SNN results from damage to large afferent fibers and presents as sensory ataxia, but patients may experience pain and paresthesia if there is damage to the small and medium-size neurons [3]. Though electrophysiological studies, neuroimaging, and clinical features are typically considered when making the diagnosis of SNN, these current methods fail to distinguish etiologies from one another [4, 5]. Considering that the etiology of SNN is deemed idiopathic in nearly half of patients, these current methods fall short in capturing the complex range of etiologies [3]. Some patients with idiopathic SNN may later develop patterns consistent with dysimmune SSN, which may suggest an underlying autoimmune mechanism [5]
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