Acute sensory ataxic neuropathy

Acute sensory ataxic neuropathy (ASAN) is a rare acquired peripheral neuropathy characterized by the rapid onset of sensory ataxia — a loss of coordination caused by impaired proprioception (the body's sense of position and movement) rather than cerebellar dysfunction. It is classified within the spectrum of acute inflammatory demyelinating or axonal neuropathies and shares features with Guillain-Barré syndrome (GBS), specifically resembling an acute sensory variant. The condition predominantly affects the peripheral nervous system, targeting large-diameter sensory nerve fibers responsible for proprioception and vibration sense. Patients typically present with an acute or subacute onset of unsteadiness, difficulty walking (sensory ataxia), numbness, tingling, and loss of deep tendon reflexes (areflexia). Limb weakness is absent or minimal, distinguishing ASAN from classic motor-predominant forms of GBS. Patients may have difficulty with fine motor tasks due to impaired sensory feedback. Nerve conduction studies typically show abnormalities in sensory nerve action potentials, while motor conduction may be relatively preserved. The condition is thought to have an immune-mediated pathogenesis, and some cases are preceded by an infectious illness. Treatment is largely supportive and based on approaches used for Guillain-Barré syndrome, including intravenous immunoglobulin (IVIg) and plasmapheresis (plasma exchange), although evidence for efficacy in this specific variant is limited and largely based on case reports and small series. Physical rehabilitation focusing on balance and gait training is an important component of management. The prognosis is variable; some patients recover substantially, while others may have persistent sensory deficits and ataxia. Given its rarity, there are no large-scale clinical trials specifically addressing ASAN, and management decisions are often individualized.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

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