areflexia

Areflexia is the absence of deep tendon reflexes (DTRs) on examination. It may be accompanied by reduced muscle tone or weakness and can be focal to a limb or generalized. Areflexia is a clinical sign rather than a disease, reflecting disturbance of the reflex arc at the level of the peripheral nerve, nerve root, spinal cord, or neuromuscular junction, or a temporary suppression of reflexes after acute injury.

Common causes fall into central, peripheral, and neuromuscular categories, and include spinal cord injury or spinal shock, cauda equina syndrome, and compressive lesions; peripheral neuropathies such as Guillain-Barré syndrome, chronic inflammatory demyelinating polyneuropathy, diabetic neuropathy; neuromuscular junction disorders such as botulism and organophosphate poisoning; tick paralysis; and certain toxins or medications. Acute areflexia is particularly characteristic of Guillain-Barré syndrome in the acute phase, while spinal shock produces areflexia after injury that may recover over days to weeks.

Evaluation relies on clinical examination of reflexes, strength, tone, and sensory findings. Diagnostic testing may include nerve conduction studies and electromyography to distinguish peripheral neuropathy from central causes; spinal MRI to detect cord injury or compression; and laboratory tests to identify infectious or inflammatory etiologies. In Guillain-Barré syndrome, cerebrospinal fluid often shows albuminocytologic dissociation.

Management targets the underlying cause and supportive care. Acute inflammatory neuropathies such as Guillain-Barré syndrome are treated with intravenous immunoglobulin or plasmapheresis; spinal shock is managed with careful monitoring and rehabilitation; botulism requires antitoxin and supportive care; removal of a tick is curative in tick paralysis. The prognosis depends on the etiology; reflexes may recover after several days to months in spinal shock and Guillain-Barré syndrome, or may be permanent in chronic neuropathies.