Hyperactive deep tendon reflexes (DTRs) refer to exaggerated muscle stretch responses elicited by tapping a tendon. This increased reflex activity often indicates upper motor neuron (UMN) lesions or neuromuscular hyperexcitability. The presence of clonus — rhythmic, involuntary contractions — further supports hyperreflexia.

Understanding the Reflex Arc

The DTR reflex arc involves:

• Afferent (sensory) neuron → Spinal cord synapse → Efferent (motor) neuron

• Controlled by inhibitory input from descending motor pathways (especially the corticospinal tract)

Pathophysiology of hyperreflexia

• UMN lesions remove inhibitory modulation → reflex arc becomes overactive

• Irritability of peripheral nerves or muscles (e.g., due to electrolyte imbalance) also enhances reflex activity

Clinical assessment

History

• Ask about:

  • Recent trauma, stroke, or neurologic disease

  • Pregnancy, especially >20 weeks (risk of preeclampsia)

  • Nutritional status, including calcium/magnesium intake

  • Toxin exposure (e.g., strychnine, lead)

  • Seizure history or altered mental status

  • Environmental exposures (e.g., cold → hypothermia)

Physical examination

• Test DTRs bilaterally (biceps, triceps, patellar, Achilles)

• Assess for clonus

• Look for associated signs:

  • Babinski's sign (UMN lesion)

  • Paresthesia, muscle cramps, tetany

  • Chvostek's and Trousseau's signs

  • Neurologic deficits: weakness, ataxia, speech/vision changes

  • Autonomic changes: blood pressure, heart rate, diaphoresis

Medical Causes

Neurological Causes

Metabolic and Electrolyte Disorders

Toxins and infections

Endocrine & Obstetric Conditions

Special considerations

Diagnostic Workup

• Laboratory:

  • Serum calcium, magnesium, electrolytes, thyroid function tests

  • Renal and liver function

  • Toxicology screen (if poisoning suspected)

• Imaging:

  • MRI or CT brain/spine (tumors, stroke, MS lesions)

  • Spinal X-rays, lumbar puncture if CNS infection suspected

• EEG: if seizures or encephalopathy suspected

Treatment Goals

• Address underlying cause (e.g., electrolytes, neurologic injury, infection)

• Prevent complications:

  • DVT → mobility exercises

  • Pressure sores → turning schedule, special mattress

  • Falls → monitor ambulation, support transfers

• Symptom control:

  • Muscle relaxants (e.g., baclofen, diazepam)

  • Magnesium sulfate for eclampsia or tetany

  • Sedation if muscle spasms are severe

Nursing Care & Monitoring

• Monitor:

  • Airway and breathing, especially in tetany or eclampsia

  • Level of consciousness, mental status

  • Vital signs: hypertension, tachycardia, bradypnea

• Provide:

  • Low-stimulation environment to reduce excitability

  • Psychological support and education for patient and family

  • Assistance with ADLs as needed

Patient counseling

• Educate caregivers about potential causes and signs of worsening (e.g., seizures, loss of consciousness)

• Explain the purpose of diagnostic tests and treatments

• Discuss safety measures, especially in cases with spasticity or altered sensation

Pediatric Pointers

• Hyperreflexia is normal in neonates; matures by age 6

• Cerebral palsy is the most common chronic cause

• Reye’s syndrome (stage II = hyperreflexia; stage V = areflexia)

• Use distraction methods during DTR testing for better reliability

Summary

References:

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