Hyperreflexia is defined as overactive or overresponsive reflexes. Examples of this can include twitching or spastic tendencies, which are indicative of upper motor neuron disease as well as the lessening or loss of control ordinarily exerted by higher brain centers of lower neural pathways (disinhibition). See Autonomic dysreflexia.
The most common cause of hyperreflexia is spinal cord injury (see autonomic dysreflexia). Standard stimuli like the filling of the bladder can cause excessive responses from the nervous system, such causes are not known.
But hyperreflexia can be developed via many other causes, including medication and stimulant side effects, hyperthyroidism, electrolyte imbalance, serotonin syndrome, severe brain trauma, multiple sclerosis, Reye syndrome, and preeclampsia.
Treatment depends on diagnosing the specific pathology causing this symptom. Should it be caused by use of stimulants or other substances, then it may involve removing these drugs from use.
Recovery of hyperreflexia can occur between several hours to several months after a spinal cord injury; however, the phase of recovery is likely to occur in stages rather than on a continuum. The late stage can be defined as between two weeks and several months. Individuals with a severe spinal cord injury (SCI) mainly present with a later stage of recovery because during the early stages they present with spinal shock. Reflex and motor recovery can sometimes return simultaneously.
- Little, J., Ditunno, J. F., Stien, S., A., Harris, R. M. (1999). Incomplete spinal cord injury: Neuronal mechanisms of motor recovery and hyperreflexia. Arch Phys Med Rehabil 80(5): 587-599.