Introduction/Aims: Sensory impairment secondary to dorsal root ganglion neuronopathy is common, although often subclinical, in X-linked spinal and bulbar muscular atrophy (SBMA).We investigated the hypothesis that nerves of SBMA patients show the same morphological changes on ultrasound as other inherited sensory neuronopathies and that these changes are distinct from those in axonal neuropathy. Methods:We compared the ultrasound cross-sectional areas (CSAs) of median, ulnar, sural, and tibial nerves of prospectively recruited SBMA patients with those of patients with acquired axonal neuropathy and healthy controls.We also compared the individual nerve CSAs of SBMA and neuropathy patients with our laboratory reference values.Results: There were 7 SBMA patients, 18 neuropathy patients, and 42 healthy controls.The nerve CSAs of the SBMA patients were significantly smaller than those of patients in the other two groups. The changes were most prominent in the upper limbs (p < .001), with the nerves of the SBMA patients being on average approximately half the size of the controls and a third the size of the neuropathy patients.On individual analysis, the ultrasound abnormality was sufficiently characteristic to be detected in all but one SBMA patient.Discussion: These ultrasound changes are similar to those reported in other inherited sensory neuronopathies and clearly different from the ultrasound findings in axonal neuropathy.Smaller nerves are possibly a distinctive finding in SBMA that may distinguish it from other motor neuron syndromes. Further studies are warranted to confirm this and determine the optimal sonographic protocol.

Case PresentationA 61-year-old European man was admitted with two days of progressive high-grade fevers, neck stiffness, and headache. He started taking ibuprofen 400 mg three times a day for an ankle sprain 24 hours prior to his symptoms. He was screened for genitourinary, gastro-intestinal, and cardiorespiratory causes for his symptoms, which were negative.Collateral history revealed previous admissions with meningitis but suggested his current presentation was more severe than the previous admissions in 2012 and 2016, neither of which yielded identifiable pathogens on lumbar puncture, despite showing neutrophilic pleocytosis. He had also taken non-steroidal anti-inflammatories (NSAIDs) prior to those admissions.The patient had no other significant medical history and took no regular medications. He was a non-drinker, an ex-smoker (5 packyears), and normally independent in his activities of daily living.On examination, the patient was tremulous and flushed. His temperature was 38.2 o C. Kernig's and Brudzinski's signs were positive, and he complained of moderate photophobia in a well-lit room. No focal neurological signs were noted, and apart from his ankle, all systems examinations were unremarkable.Blood tests revealed mildly elevated inflammatory changes (C-reactive protein 8 mg/L and white cell count (WCC) 15.1x10 3 /µL). Liver, thyroid, and renal function tests were normal, as were electrolytes, B12, folate, creatine kinase, and lipase. Blood cultures, human immunodeficiency virus (HIV), and Treponemal serology were negative. Head imaging with computed tomography (CT) and magnetic resonance imaging (MRI) was normal, and a lumbar puncture showed a neutrophilic pleocytosis (WCC 67x10 6 /L; 54% neutrophils) with raised protein (820 mg/L) and normal glucose (2.8 mmol/L). Cerebrospinal fluid (CSF) cultures were sterile, and a polymerase chain reaction (PCR) panel was negative for herpes simplex virus 1 and 2, varicella zoster virus, Neisseria meningitidis, Streptococcus pneumoniae, Haemophilus influenzae, and enterovirus. There were no other sources of infection found through either a CT chest or echocardiogram.

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