Radiculopathies

Radiculopathies

Radiculopathies are very frequently encountered in clinical practice. The most common deferential diagnosis includes:

Non-Neuromuscular (orthopedic) Lesions:

  • Muscle strain/sprain
  • Rotator cuff tendonitis/tear
  • Subacromial/trochanteric bursitis
  • Epicondylitis
  • Degenerative joint disease

Neuromuscular Lesions:

  • Motor neuron disease
  • Brachial and Lumbosacral Plexopathy
  • Mononeuropathy
  • Polyneuropathy

Cervical Radiculopathies:

  • C5: 2 – 14%
  • C6: 19 – 25%
  • C7: 56 – 70%
  • C8: 4 – 12%

Lumbar Radiculopathies:

  • L2/3
  • L4
  • L5 : most common
  • S1: second to L5

The goal of the EMG is to localize the compressed, and to establish the presence or absence of active axonal loss and/or chronic reinnervation changes. A very important role of the NCS/EMG is to evaluate for presence of a “Double Crush Syndrome”, in which a distal mononeuropathy is superimposed. The electrophysiologic abnormalities in radiculopathies include:

Possible abnormalities in motor NCS:

  • Normal sensory NCS (lesion is proximal to DRG)
  • Possible active denervation in appropriate myotome and paraspinals
  • Very important limitations of EMG in radiculopathies are:
  • Absence of abnormalities in acute lesions (< 2 weeks)
  • “Normal” EMG in purely demyelinating lesions (no denervation)
  • “Normal” EMG in lesions limited to the sensory nerve root

Medical illustrations on this website are attributed to: Freepik.com and author Kjpargeter

Lateral Femoral Cutaneous Nerve

From: www.wheelessonline.com 

– Anatomy:    

– LFCN, as its name suggests, is purely sensory;    
– it arises from L2 and L3, travels downward lateral to the psoas muscle, crosses the iliacus muscle (deep to fascia), passes either thru or underneath the lateral aspect of the inguinal ligament, and finally travels onto innervate the lateral thigh;
– it divides into anterior and posterior branches and supplies skin on lateral aspect of thigh;
– in the study by Hospodar et al (JTO 1999), the course of the nerve was variable, but was most commonly found at 10-15 mm from the ASIS and as far medially as 46 mm from the ASIS;
– in no specimen did the nerve pass lateral to the ASIS (eventhough historically the nerve is thought to pass lateral to the ASIS in 10% of population);
– in all specimens the nerve passed underneath the ilioginal ligament and anterior to the iliacus muscle; 

– Meralgia Paresthetica: 

– entrapment syndrome of the lateral femoral cutaneous nerve causing burning, numbness, and paresthesias down the proximal-lateral aspect of the thigh;
– may be idiopathic, be a result of trauma, previous operations, and in some cases may arise from Perthes Disease abduction splints;
– in idiopathic cases, the nerve may be encased in bone by the growing apophysis of the anterior superior iliac spine, or may be entrapped in fascia either proximal or distal to the ASIS;    
– diagnosis is made by:           
– reproduction of the pain by deep palpation just below the anterior superior iliac spine and by hip extension;           
– relief of pain by localized injection of lidocaine;    
– treatment: when diagnosis is not in doubt and the symptoms are severe, consider operative decompression at the site of constriction;

EMG and NCS

Electromyography (EMG) and nerve conduction studies (NCS) are tests that measure the electrical activity of muscles and nerves. Nerves send out electrical signals to make your muscles react in certain ways. Nerves also send signals from your skin to your brain, which then processes the signals, so you can experience a variety of skin sensations.

  • An EMG Test looks at the electrical signals your muscles make when they are at rest and when they are being used.
  • A Nerve Conduction Study measures how fast and how well the body’s electrical signals travel along your nerves. EMG and nerve conduction studies are used to help diagnose a variety of muscle and nerve disorders and to quantify the severity of your condition.


An EMG test helps find out if muscles are responding the right way to nerve signals. Nerve conduction studies help diagnose nerve damage or disease. When EMG tests and nerve conduction studies are done together, they help doctors tell if your symptoms are caused by a muscle disorder or a nerve problem. With EMG and NCS studies, your doctor can next select the best therapeutic option to help you.