Nerve injuries are classified into how many broad categories?

Peripheral nerve injuries are frequently encountered in clinical practice and often result in functional disability. In the past, due to poor understanding of pathophysiology, the results of nerve repair were unpredictable. Sunderland in 1945 described the microsurgical techniques which improved the results of nerve repair.

Nerve injuries types are classified into three broad categories; neurapraxia, axonotmesis, and neurotmesis.

In neurapraxia, transient functional loss is observed without affecting loss of nerve continuity. A complete disruption of the nerve axon and surrounding myelin along with preservation of perineurium and epineurium is observed in axonotmesis. Neurotmesis causes complete functional loss because of disconnection of a nerve.

While complete recovery is expected in neuropraxia and axonotmesis, neurotmesis will not recover without surgical intervention. This distinction may be difficult at times and hence there is a role for electrophysiological studies in the diagnosis of nerve injuries. They are also helpful in documenting recovery and in the diagnosis of compressive neuropathies.