Abnormal Reflexes

Overview

Reflexes are automatic responses, such as the leg kick when the knee is tapped, that depend on a healthy loop between the muscles, nerves, spinal cord, and brain. Abnormal reflexes are responses that are exaggerated (hyperreflexia), reduced or absent (hyporeflexia), or that should not be present at all in adults.

Abnormal reflexes are usually found by a clinician during a neurological examination rather than noticed by the person themselves. They are a sign rather than a disease, and the pattern helps locate where in the nervous system a problem may lie. Overactive reflexes often suggest a problem in the brain or spinal cord, while reduced reflexes often point to the peripheral nerves. Abnormal reflexes are evaluated alongside other findings such as weakness, numbness, and coordination.

Reflexes are useful to clinicians precisely because they are automatic and cannot be consciously controlled, so they give an objective window into how the nervous system is working. Doctors test several reflexes, such as those at the knee, ankle, elbow, and wrist, and also check for special signs that should not appear in healthy adults. The combination of which reflexes are abnormal, whether they are increased or decreased, and where in the body they occur helps map the location of a problem, which is why a careful examination is so valuable even before any imaging or other tests are done.

Common Causes

The cause of abnormal reflexes depends on whether they are increased or decreased and where in the body they occur.

• Overactive reflexes (hyperreflexia): Often from conditions affecting the brain or spinal cord, such as stroke, spinal cord injury, or multiple sclerosis.
• Reduced or absent reflexes (hyporeflexia): Often from peripheral nerve damage, such as in diabetes or other neuropathies, or from nerve compression.
• Spinal nerve compression: A herniated disc or other pressure on a nerve root can reduce a specific reflex.
• Metabolic causes: Thyroid disease and electrolyte imbalances can affect reflexes.
• Newborn reflexes returning: Certain reflexes that are normal in babies but abnormal in adults can reappear with brain conditions.

Associated Symptoms

Because abnormal reflexes reflect nervous system problems, they are evaluated together with other neurological symptoms.

• Muscle weakness
• Numbness, tingling, or loss of sensation
• Muscle stiffness or spasticity
• Problems with balance or coordination
• Changes in walking
• Muscle wasting in long-standing nerve problems

Diagnosis & Evaluation

Abnormal reflexes are identified and interpreted as part of a full neurological evaluation.

• Neurological examination: Testing reflexes with a reflex hammer along with strength, sensation, and coordination to locate the problem.
• Imaging: MRI or CT of the brain or spine when a central cause is suspected.
• Nerve studies: Nerve conduction studies and electromyography (EMG) assess peripheral nerve and muscle function.
• Blood tests: To check for diabetes, thyroid problems, vitamin deficiencies, and electrolyte imbalances.

Treatment & Management

There is no treatment for an abnormal reflex itself; care is directed at the underlying condition.

• Treating the cause: Managing stroke, multiple sclerosis, diabetes, or thyroid disease addresses the root problem.
• Relieving nerve compression: Physical therapy, medication, or surgery may be used for a compressed nerve.
• Managing spasticity: Stretching, physical therapy, and certain medications can ease overactive reflexes and muscle tightness.
• Correcting metabolic problems: Treating thyroid disease or electrolyte imbalances can normalize reflexes.
• Rehabilitation: Physical and occupational therapy support strength, mobility, and function.

Self-Care & Prevention

• Manage chronic conditions like diabetes and high blood pressure to protect nerves and the brain
• Maintain a balanced diet to avoid vitamin deficiencies that harm nerves
• Limit alcohol, which can damage nerves over time
• Report new weakness, numbness, or balance problems to a clinician promptly
• Attend follow-up appointments for known neurological conditions

When to See a Doctor

Abnormal reflexes should always be evaluated by a clinician in the context of other symptoms. Seek emergency care right away if abnormal reflexes appear suddenly with:

• Sudden weakness or numbness, especially on one side of the body
• Trouble speaking, drooping of the face, or vision changes, which can signal a stroke
• Sudden loss of bladder or bowel control with leg weakness, which can signal spinal cord compression
• Severe or rapidly worsening weakness or difficulty walking

Otherwise, see a doctor promptly for any new or unexplained neurological symptoms.

Related Topics

Frequently Asked Questions

References

1. National Institute of Neurological Disorders and Stroke (NINDS).
2. Mayo Clinic. Neurological examination.
3. MedlinePlus, U.S. National Library of Medicine. Reflexes.
4. Merck Manual. Evaluation of the Neurologic Patient.