Areflexia, from the Greek word “a”, meaning absence, is a medical condition characterized by the absence or reduction of reflexes. Reflexes are involuntary response triggered by sensory stimuli that are essential for maintaining proper bodily function. When this complex system fails, it shows as areflexia, which causes a variety of symptoms across multiple systems in the body. There are multiple types of areflexia, each with different symptoms and related ataxia type.
Vestibular Areflexia
Vestibular areflexia is characterized by malfunction of the vestibular system, which oversees balance and spatial orientation. Relevant ataxias include RFC1 Ataxia or Cerebellar Ataxia Neuropathy Vestibular Areflexia Syndrome (CANVAS). Patients with this condition frequently report vertigo, dizziness, and difficulty keeping balance. They may sway or stumble, particularly while walking over uneven terrain or changing postures quickly. Nystagmus, an involuntary rhythmic movement of the eyes, may also occur. Vestibular areflexia can have significant impacts on an individual’s quality of life, making it difficult to accomplish daily tasks that require coordination and spatial awareness.
Autonomic Areflexia
Autonomic areflexia results from malfunction in the autonomic nervous system, which regulates involuntary bodily functions such as heart rate, blood pressure, and digestion. Symptoms of autonomic areflexia include orthostatic hypotension, urinary retention, and digestive problems, amongst others. Multiple System Atrophy (MSA) is a common condition associated with autonomic areflexia, which can also be seen in many other ataxias. Individuals with MSA frequently exhibit substantial autonomic dysfunction, which causes symptoms such as dizziness upon standing (often referred to as postural orthostasis), urinary retention, and constipation. Combined with motor symptoms, autonomic dysregulation can contribute to the overall disability from various neurological disorders.
Spinal Areflexia
Spinal Areflexia is the lack or reduction of reflexes mediated by the spinal cord, which affects motor function and coordination. Peripheral neuropathy, a condition in which there is damage to the peripheral nerves that transmit information between the central nervous system and the environment, is a common cause of spinal areflexia. Spinal cord injuries are another major cause of spinal areflexia. Symptoms of spinal areflexia may include muscle weakness, loss of tendon reflexes, and difficulty controlling movement. While spinal areflexia is a rare symptom in sporadic ataxias, it can have a major impact on people’s motor ability. Patients with this condition may present with an unstable gait, clumsiness, and difficulty carrying out fine motor skills.
If you would like to learn more about areflexia, take a look at these resources by the Cleveland Clinic.
Snapshot Written by:Lin (Summer) Dong
Edited by: Sharan Srinivasan, MD
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