Cervical radiculopathy

Levels involved: C5 (6.6%), C6 (17.6%), C7 (46 %) C8 (6.3%) Most usual NCS are C8T1; C5-6 NCS (musculocutaneous/biceps) and C7 (radial EDC) are uncommonly studied. CMAPs should be normal unless there is severe axon loss. Other nerves that can be studied are lateral antebrachial (C5), median recording at index or thumb (C6), median recording at middle finger (C7) or ulnar at ring/little finger (C8) or median antebrachial (T1). Contrary to popular belief, paraspinal muscles are abnormal in only 50-70 % of radiculopathies. Planning the EMG (below) the muscles associated with radiculopathy at the variousl levels are indicated, in order of the chances of their being abnormal. C5. Clinically presents with weak deltoid and infraspinatus. Check deltoid, infrapinatus, biceps, then less often, brachioradialis and rhomboids (rhomboids are usually SPARED). Reach INF with arm abducted at ninety degrees, insert needle 2 finger breadths below the spine of the scapula. Reach rhomboid major on vertebral border of the scapula, from the root of the spine of the scapula to the inferior angle. Patient's hand is at side, test by raising hand from small of the back. Pitfall: if superficial needle will be in trapezius; if deep, in the erector spinae. Rhomboideus minor is just above major with needle insertion one finger breadth medial to vertebral end of the scapular spine with same activation. Pearl: Check pronator teres (C6) to rule out C6 involvement. Reach pronator teres two finger breadths distal to the midpoint of a line connecting the medial epicondyle and the insertion of the biceps tendon. C6 presents with paresthesias into thumb and forefinger; weak biceps and wrist extensors. Abnormal muscles are pronator teres (median C6), deltoid, biceps, triceps, ECR ( upper trunk radial C6). Reach ECR 2 fingerbreadths distal to the lateral epicondyle. It dorsiflexes the wrist in radial deviation. C7 causes paresthesias in forearm and dorsum of hand; weak triceps, long finger flexors and finger extensors. This is the most common radiculopathy. Use multiple nerve distributions. Abnormal muscles are triceps, PT, ECR, EDC and FCR (median all trunks C6-8). Find FCR 3-4 fingerbreadths distal to the midpoint of a line connecting the medial epicondyle and biceps tendon; it flexes the wrist with radial deviation. Other muscles nearby (can hit accidentally) are FDS (deep), FPL (deeper) PT (lat) palmaris longus (medial). Radial artery, FPL and FCR make up "radial trio." Its important to get PT or FCR as a median contributor. C8 involves paresthesias in the little finger and weak intrinsic mm of hand and wrist flexors. Check (in order) FDI, APB (median), FPL, EIP, EDC, TRI, PT, ADM. Pitfalls: ulnar and medial antebrachials should be normal. Consider ALS. Find FPL in middle of the forearm with hand supinated, flexes DIP of thumb. Favors radiculopathy: Pain proximally, in neck or with movement of the neck, along the scapula or the precordial border; pain with coughing, sneezing, or Vasalva maneuvers;

Upper extremity

Root
Clinically Relevant Gross Motor Function
C5
Shoulder abduction; ± elbow flexion
C6
Elbow flexion, pronation/supination, ± wrist extension
C7
Diffuse loss of function in the extremity without complete paralysis of a specific muscle group
C8
Finger extensors, finger flexors, wrist flexors, hand intrinsics
T1
Hand intrinsics