What Are the Basic Categories of Traumatic Peripheral Nerve Injury?

Patient Presentation
A 16-year-old male came to clinic after hitting a brick wall with a left closed fist during a basketball game the previous evening. He had iced the hand, took ibuprofen and it felt somewhat better. The following morning though he was having more pain that was radiating from the wrist upwards. He also complained that he had pain and tingling when he moved his elbow that would radiate toward the wrist. The past medical history was non-contributory. The pertinent physical exam revealed normal vital signs and growth parameters. His extremity examination showed abrasions and swelling on the dorsum and knuckles of the left hand. His muscle strength in the arm, hand and fingers was normal. His range of motion was normal in the shoulder, and decreased flexion/extension at the elbow because flexion caused increased pain/tingling down the forearm along the ulnar nerve distribution. He had decreased range of motion in the wrist and 4th and 5th fingers again because of pain. He could make a fist and moved all fingers otherwise. There was no specific point tenderness but he complained most about the 5th metacarpal and wrist area. Capillary refill was brisk in all fingers and he had good pulses. Tapping on the ulnar nerve in the ulnar grove of the elbow or near the wrist made the tingling/pain worse and the sensation changes involved the ulnar distribution of the hand and forearm. The radiologic evaluation showed no fracture in the hand, wrist, forearm or elbow.

The diagnosis of soft tissue injuries with irritation of the ulnar nerve presumably in the elbow and hand was made. After discussion with an orthopaedic physician because of the ulnar nerve changes, the primary care physician sent the teenager home to followup in 2 weeks with the physician. The primary care physician called the patient 2 days later and found out that the patient was having increased pain despite using a sling to support his arm. He was seen the following day by orthopaedics and repeat radiographs showed a periosteal break in the 5th metacarpal consistent with a Boxer’s fracture. The patient was placed into a custom-made splint and was to followup with orthopaedics in 2 weeks.

Discussion
The ulnar nerve begins in the brachial plexus and travels anterior to the medial head of the triceps in the upper arm. It then moves through the elbow at the condylar groove to the cubital tunnel, then between the two heads of the flexor carpi ulnaris in the forearm to the wrist. In the wrist it moves through the Guyon canal after which it splits to innervate the hand’s intrinsic muscles and gives sensation to the 4th and 5th fingers and lateral hand.

To review the anatomy and anatomic variation click here.

Compression of the nerve by abnormal positioning (during sleep or otherwise), crutches, tourniquets, compartment syndrome, hematomas and fractures commonly cause a chronic neuropathy. Ulnar neuropathies occur mainly at the elbow and the wrist because this is where the nerve is vulnerable. Ulnar neuropathy is one of the most common peripheral neuropathies after median nerve neuropathy due to carpal tunnel syndrome. Most symptoms are parathesia or numbness in the ulnar distribution, but motor symptoms can also occur ranging from severe muscle wasting and claw hands to minor weakness.

Learning Point
Acute peripheral nerve injury due to trauma is often caused by traction, compression, ischemia, or laceration. The nerve axon, myelin or both elements may be injured. There are 3 basic categories of traumatic peripheral nerve injury:

• Neuropraxia
  • Axon is normal but there is segmental demyelination
  • Motor function loss, sensory and sympathetic losses are incomplete
  • Prognosis is good with recovery as early as hours to days but most within 3 months
• Axonotmesis
  • Axon is injured but the myelin is preserved
  • Motor, sensory and sympathetic function are lost
  • Prognosis is varied because axonal regeneration may be incomplete or aberrant, time course is varied but much longer than neuropraxia
• Neurotmesis
  • Axon and myelin are both injured
  • Motor, sensory and sympathetic function are lost
  • Prognosis is poor because regeneration does not occur. Deficits are permanent and muscle atrophy occurs within 18-20 months. Surgical reanastomosis offers some possibilities of improved outcome.

Questions for Further Discussion
1. What are acquired causes of chronic peripheral neuropathy?
2. What are genetic syndromes of chronic peripheral neuropathy?

Related Cases

Disease: Peripheral Nerve Disorders

Symptom/Presentation: Extremity Problems

Specialty: Orthopaedic Surgery and Sports Medicine

Age: Teenager

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at SearchingPediatrics.com, the National Guideline Clearinghouse and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for this topic: Peripheral Nerve Disorders

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

To view videos related to this topic check YouTube Videos.

Felice KJ, Royden Jones H Jr. Pediatric ulnar mononeuropathy: report of 21 electromyography-documented cases and review of the literature. J Child Neurol. 1996 Mar;11(2):116-20.

Papazian O, Alfonso I, Yaylali I, Velez I, Jayakar P. Neurophysiological evaluation of children with traumatic radiculopathy, plexopathy, and peripheral neuropathy. Semin Pediatr Neurol. 2000 Mar;7(1):26-35.

Doherty, TJ. Ulnar Neuropathy at the Elbow and Wrist. UpToDate. (rev. 11/16/12, cited 8/29/13).

Landau ME, Campbell WW. Clinical features and electrodiagnosis of ulnar neuropathies. Phys Med Rehabil Clin N Am. 2013 Feb;24(1):49-66.

Kroonen LT. Cubital tunnel syndrome. Orthop Clin North Am. 2012 Oct;43(4):475-86.

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