A pole vaulter had a fall during pole vaulting and had paralysis of the arm. Which of the following investigations gives the best recovery prognosis.

EMG (electromyography) is by far the most reliable and effective test to predict about nerve recovery. Diagnostic Tests for Nerve Injuries: EMG: Denervation fibrillation potentials. Appears at 2-3 weeks then spontaneous fibrillation. EMG is the earliest indicator of nerve recovery. Nerve conduction study: reduced in axonotmesis and neurotmesis but cannot differentiate between the 2. Normal nerve conduction velocity on day 10 goes toward neuropraxia. No conduction will indicate neurotmesis. Sweat Test: In autonomous area, presence of sweat rules out complete injury as sweat fibers are most resistant to compression. MRI: Value only in nerve root lesions (e.g. Brachial plexus injuries).