How do I get a nerve conduction study (NCS) for right lower extremity paresthesia?

Referring a Patient for Nerve Conduction Study for Right Lower Extremity Paresthesia

To obtain a nerve conduction study for right lower extremity paresthesia, you should refer the patient to a neurologist or physiatrist (physical medicine and rehabilitation specialist) who performs electrodiagnostic testing.

Initial Assessment Before Referral

Before making the referral, perform a focused assessment:

1. Vascular Examination:

   • Palpate lower extremity pulses (femoral, popliteal, dorsalis pedis, posterior tibial)
   • Auscultate for femoral bruits
   • Inspect legs and feet for skin changes, ulceration, or hair loss 1

2. Neurological Examination:

   • Assess pinprick sensation
   • Test vibration threshold using 128-Hz tuning fork
   • Evaluate light touch perception using 10-g monofilament
   • Check ankle reflexes 1
   • Document distribution of paresthesia (stocking-glove, dermatomal, or other pattern)

3. Rule out Peripheral Arterial Disease (PAD):

   • If PAD is suspected, perform ankle-brachial index (ABI) testing
   • ABI ≤0.90 indicates PAD 1
   • If ABI is >1.40 (noncompressible), toe-brachial index should be measured 1

Making the Referral

When to Refer for Nerve Conduction Studies

Refer for nerve conduction studies when:

• Symptoms persist despite conservative management
• Symptoms are progressive or severe
• Diagnosis remains unclear after initial evaluation
• Need to differentiate between various causes of neuropathy (diabetic, compressive, inflammatory)
• Need to determine if the condition is axonal or demyelinating 1

What to Include in the Referral

1. Clinical Information:

   • Detailed description of symptoms (onset, duration, progression)
   • Distribution of paresthesia
   • Associated symptoms (weakness, pain, numbness)
   • Relevant medical history (diabetes, alcohol use, medications)
   • Physical examination findings 2

2. Specific Request:

   • Clearly state "Nerve Conduction Study and Electromyography (EMG) of right lower extremity for evaluation of paresthesia"
   • Include any specific diagnostic considerations (e.g., "to rule out peripheral neuropathy vs. radiculopathy")

3. Urgency Indication:

   • Specify if urgent (progressive weakness, severe symptoms) or routine

Understanding the Test

Nerve conduction studies (NCS) involve:

• Electrical stimulation of a nerve and recording the response
• Motor nerve conduction studies measure response from muscle
• Sensory nerve conduction studies measure response from sensory nerve
• Electromyography (EMG) involves inserting a needle electrode into muscles to record electrical activity 1

These tests can help differentiate between:

• Peripheral neuropathy
• Radiculopathy
• Plexopathy
• Mononeuropathy (single or multiplex) 1

Important Considerations

1. Patient Preparation:

   • Inform patients that the procedure may cause mild discomfort
   • No special preparation is typically needed, but patients should avoid using lotions or oils on the day of testing
   • Patients should bring a list of current medications 1

2. Test Limitations:

   • Early in disease course, electrodiagnostic studies might be normal
   • Tests are operator-dependent and require specialized training
   • Tests can take up to 2 hours to complete 1
   • Small fiber neuropathy may not be detected by routine NCS 3

3. Follow-up Plan:

   • Schedule a follow-up appointment to review results and determine treatment plan
   • Consider additional testing if NCS/EMG results are inconclusive but symptoms persist

Common Pitfalls to Avoid

• Failing to perform a thorough clinical assessment before referral
• Not providing adequate clinical information to the specialist
• Overlooking vascular causes of lower extremity symptoms
• Not considering other diagnostic tests when appropriate (e.g., MRI for suspected radiculopathy) 4
• Delaying referral in cases of progressive neurological deficits

By following this approach, you can ensure appropriate and timely evaluation of patients with right lower extremity paresthesia through nerve conduction studies.