What is the appropriate management for abnormal DTR (Deep Tendon Reflexes)?

Management of Abnormal Deep Tendon Reflexes (DTR)

The management of abnormal deep tendon reflexes should focus on identifying and treating the underlying cause, as DTRs are important diagnostic indicators of neurological dysfunction rather than primary conditions requiring direct treatment.

Assessment and Interpretation of Abnormal DTRs

Types of DTR Abnormalities

• Hyperreflexia (increased/brisk reflexes)

  • Indicates upper motor neuron dysfunction
  • Often accompanied by other signs like Babinski sign (extensor plantar reflex)
  • Associated with central nervous system pathology (brain, spinal cord)

• Hyporeflexia/Areflexia (decreased/absent reflexes)

  • Indicates peripheral nerve dysfunction, lower motor neuron problems, or neuropathy
  • Often accompanied by sensory changes and/or weakness
  • May be asymmetric or symmetric depending on pathology

Diagnostic Approach

1. Comprehensive DTR Examination

   • Assess symmetry between left and right sides
   • Compare upper vs. lower extremity reflexes
   • Document using standardized grading (0-4+ scale)
   • Note force required to elicit reflexes (hyperreflexia: 0-20 Newtons; normal: 21-50 Newtons; hyporeflexia: >50 Newtons) 1

2. Associated Neurological Signs

   • Evaluate for sensory changes, weakness, muscle tone abnormalities
   • Check for pathological reflexes (Babinski sign, clonus)
   • Assess for autonomic dysfunction
   • Evaluate cranial nerve function when appropriate

Management Based on Underlying Cause

1. Medication-Induced Neuropathy

For chemotherapy-induced peripheral neuropathy with reduced DTRs:

• Bortezomib-induced neuropathy

  • Dose modification or discontinuation based on severity 2
  • For grade 1 neuropathy (mild symptoms): continue treatment
  • For grade 2-3 neuropathy (moderate-severe symptoms): dose reduction or temporary discontinuation
  • For grade 4 (disabling): permanent discontinuation

• Thalidomide-induced neuropathy

  • Monitor regularly as 70% develop neuropathy after 12 months of treatment 2
  • Consider dose reduction or discontinuation with significant sensory symptoms

• Other chemotherapeutic agents (platinum compounds, taxanes)

  • Regular neurological assessment before each cycle 2
  • Dose adjustment based on severity of neuropathy

2. Immune-Mediated Neuropathies

• Guillain-Barré Syndrome (GBS)

  • Characterized by progressive weakness and areflexia 2
  • Immediate hospitalization for patients with significant weakness or progression
  • Treatment with IVIG (0.4 g/kg/day for 5 days) or plasmapheresis 2
  • Methylprednisolone (2-4 mg/kg/day) may be considered, especially for immune checkpoint inhibitor-related forms 2
  • Respiratory monitoring and supportive care

• Immune Checkpoint Inhibitor-Related Neuropathy

  • For grade 2 (moderate symptoms): hold immunotherapy and consider corticosteroids 2
  • For grade 3-4 (severe symptoms): permanently discontinue immunotherapy, admit patient, consider IVIG or plasmapheresis 2

3. Metabolic and Systemic Causes

• Hypocalcemia

  • Correct calcium levels when associated with hyperreflexia or tetany
  • Address underlying cause (vitamin D deficiency, hypoparathyroidism)

• Hypothermia

  • Loss of DTRs occurs with severe hypothermia 2
  • Active rewarming to restore normal neurological function
  • DTRs should return with normalization of temperature

4. Central Nervous System Disorders

• Upper Motor Neuron Lesions (stroke, multiple sclerosis, spinal cord injury)
  • Hyperreflexia management focuses on treating underlying condition
  • Consider antispasticity medications for associated spasticity
  • Physical therapy to maintain range of motion

5. Genetic and Developmental Disorders

• 22q11.2 Deletion Syndrome
  • Regular neurological evaluation recommended at diagnosis 2
  • Investigate focal neurological findings, muscle weakness, or abnormal DTRs
  • Consider brain MRI for significant abnormalities
  • For lower limb upper motor neuron signs, consider lumbar spine MRI to rule out tethered cord 2

Special Considerations

Diagnostic Testing for Abnormal DTRs

1. Electrodiagnostic Studies

   • Nerve conduction studies and EMG for suspected peripheral neuropathy
   • May be normal early in disease course (within 1 week of symptom onset) 2
   • Consider repeat studies 2-3 weeks later if initial results are normal but clinical suspicion remains high

2. Laboratory Testing

   • Based on suspected etiology: calcium, magnesium, vitamin B12, thyroid function
   • Consider inflammatory markers, autoimmune panels for suspected immune-mediated causes

3. Imaging

   • MRI of brain/spine for suspected central lesions
   • Consider cervical spine imaging in patients with 22q11.2 deletion syndrome 2

Pitfalls in DTR Assessment

• Examiner technique and patient factors can affect reliability 3
• Consider using reinforcement techniques (Jendrassik maneuver) for hyporeflexic patients
• Angular velocity is the most reliable parameter for quantitative assessment 4

Follow-up Recommendations

• Regular neurological reassessment based on underlying condition
• Monitor for progression or resolution of abnormal DTRs
• Adjust treatment plan based on clinical response and disease course

Remember that DTRs are valuable diagnostic indicators rather than primary therapeutic targets. The management focuses on addressing the underlying neurological condition causing the abnormal reflexes.