Inflammatory sensory neuronopathies are rare disorders mediated by dysimmune mechanisms targeting sensory neurons in the dorsal root ganglia. They constitute a heterogeneous group of disorders with acute, subacute, or chronic courses, and occur with cancer, systemic autoimmune diseases, notably Sjögren syndrome, and viral infections but a noticeable proportion of them remains isolated. Identifying inflammatory sensory neuronopathies is crucial because they have the potential to be stabilized or even to improve with immunomodulatory or immunosuppressant treatments provided that the treatment is applied at an early stage of the disease, before a definitive degeneration of neurons. Biomarkers, and notably antibodies, are crucial for this early identification, which is the first step to develop therapeutic trials.

Posterior spinal cord lesions are found in patients with ganglionopathy. These are normally found in later stages of the neuronopathy as a consequence of dorsal root ganglia degeneration. Cerebellar Ataxia, Neuropathy, Vestibular Areflexia Syndrome (CANVAS) is an emerging neurological disorder. Myelitis lesions have been described in confirmed CANVAS cases. We describe a case of a 68-year-old woman with slowly progressive ataxia with paresthesia. Laboratory tests were normal. Total spine MRI showed a C4 posterior spinal cord lesion. Lumbar puncture was positive for oligoclonal bands with normal IgG index and protein level. Paraneoplastic antibodies were not detected. Electromyography showed nonlength dependent sensory neuropathy. The patient was treated with intravenous immunoglobulin for suspected dysimmune myelitis. Over 6 years, she progressively developed other neurological manifestations evoking CANVAS. Nerve conduction study showed isolated sensory impairment over the years and peripheral nerve ultrasound revealed abnormally small nerves. Further genetic testing confirmed the diagnosis. This is the first case of CANVAS syndrome presenting initially with an isolated spinal cord lesion mimicking dysimmune myelitis. The purpose of this case report is to add to the current literature about this evolving neurological syndrome and to aid clinicians in their diagnostic approach in clinical practice.

Disorders of the nervous system can produce a variety of gastrointestinal (GI) dysfunctions. Among these, lesions in various brain structures can cause appetite loss (hypothalamus), decreased peristalsis (presumably the basal ganglia, pontine defecation center/Barrington's nucleus), decreased abdominal strain (presumably parabrachial nucleus/Kolliker-Fuse nucleus) and hiccupping and vomiting (area postrema/dorsal vagal complex). In addition, decreased peristalsis with/without loss of bowel sensation can be caused by lesions of the spinal long tracts and the intermediolateral nucleus or of the peripheral nerves and myenteric plexus. Recently, neural diseases of inflammatory etiology, particularly those affecting the PNS, are being recognized to contribute to GI dysfunction. Here, we review neuroinflammatory diseases that potentially cause GI dysfunction. Among such CNS diseases are multiple sclerosis, neuromyelitis optica spectrum disorder, myelin oligodendrocyte glycoprotein associated disorder, and autoimmune encephalitis. Peripheral nervous system diseases impacting the gut include Guillain-Barre syndrome, chronic inflammatory demyelinating polyneuropathy, acute sensory-autonomic neuropathy/acute motor-sensory-autonomic neuropathy, acute autonomic ganglionopathy, myasthenia gravis and acute autonomic neuropathy with paraneoplastic syndrome. Finally, collagen diseases, such as Sjogren syndrome and systemic sclerosis, and celiac disease affect both CNS and PNS. These neuro-associated GI dysfunctions may predate or present concurrently with brain, spinal cord or peripheral nerve dysfunction. Such patients may visit gastroenterologists or physicians first, before the neurological diagnosis is made. Therefore, awareness of these phenomena among general practitioners and collaboration between gastroenterologists and neurologists are highly recommended in order for their early diagnosis and optimal management, as well as for systematic documentation of their presentations and treatment.

Sensory neuronopathies are heterogeneous disorders of dorsal root ganglia. The clinical and laboratory features in a single-centre series, including response to treatment and outcome have been described. They retrospectively included 54 patients meeting Camdessanché et al (2009) criteria for sensory neuronopathy. The patients were classified according to their likely aetiology and analysed their demographic, clinical, neurophysiological, histological and spinal MRI features. The outcome with the modified Rankin Scale (mRS) was evaluated, and the response to treatment was assessed. About 54 patients were included (18 male; median age 54.5 years). The most common initial symptoms were hypoaesthesia, paraesthesia, ataxia and pain. Half of patients had a slow onset, greater than 12 months before seeing a neurologist. The aetiology as possibly inflammatory (meaning nonspecific laboratory evidence of immune abnormality) in 18 patients (33%), paraneoplastic 8 (15%), autoimmune 7 (13%) and idiopathic 6 (11%) was classified. About 31 patients received immune therapy of which 11 (35%) improved or stabilised. Corticosteroids were the most used treatment (24 patients) and cyclophosphamide had the highest response rate (3/6, 50%). At the final follow up (median 24 months) 67% had mRS ≥3 and 46% mRS ≥4, including 15% who died. Worse outcome was associated with generalised areflexia and pseudoathetosis by logistic regression, and with motor involvement and raised CSF protein by univariate analysis. Sensory neuronopathies caused severe disability, especially in patients with generalised areflexia and pseudoathetosis. Of those without an obvious cause, most had some evidence of dysimmunity. Some patients had a positive response to immunotherapy, but rarely enough to improve disability much.