reflexia

Reflexia is a neurological sign describing the absence or loss of reflex responses, typically the deep tendon reflexes, to a standard stimulus during examination. In clinical practice is commonly termed areflexia. It is distinguished from hyporeflexia (reduced reflexes) and hyperreflexia (exaggerated reflexes).

Causes and mechanism: Areflexia results from disruption of any part of the reflex arc, including sensory afferents, spinal cord pathways, motor efferents, the neuromuscular junction, or the muscle itself. It may be temporary, as in acute conditions like spinal shock after spinal cord injury, or persistent in peripheral nerve disease, motor neuron disease, or certain neuromuscular disorders.

Clinical features and evaluation: Areflexia is identified by absent deep tendon reflexes on examination and often accompanied by reduced muscle tone in peripheral (lower motor neuron) causes. Central nervous system lesions can produce hyperreflexia and spasticity, though early spinal shock may present with areflexia. Evaluation involves standardized reflex testing (e.g., patellar and Achilles tendons) and assessment of accompanying signs such as sensation, strength, tone, plantar responses, clonus, and signs of upper motor neuron involvement.

Common etiologies: Acute spinal cord injury with spinal shock; peripheral neuropathies such as diabetes mellitus–related or alcohol-related neuropathy; radiculopathies; Guillain-Barré syndrome and other inflammatory polyneuropathies; anterior horn cell diseases; neuromuscular junction disorders and certain toxins. Metabolic or nutritional deficiencies, including hypothyroidism or vitamin B12 deficiency, can contribute to reduced reflexes.

Management: Focuses on treating the underlying cause, with supportive care and rehabilitation as needed. In suspected spinal injury, urgent evaluation and stabilization are essential.