Review Question - QID 217528

This patient has a complete nerve root avulsion of C6 and surgical intervention with nerve transfers should be performed as there is no chance for spontaneous recovery of C6.

Brachial Plexus Birth Injury (BPBI) is an upper extremity paralysis secondary to a traction injury of the nerves of the brachial plexus that occurs during the perinatal period. The incidence of BPBIs is reported to be 0.38 – 1.56 per 1000 live births. BPBI patterns can be broadly categorized in relation to the location of the injury to the dorsal root ganglia (DRG). Preganglionic injuries occur proximal to the DRG and occur when the spinal nerve roots are avulsed directly from the spinal cord. Hence, there is no potential for spontaneous recovery, and these injuries require reconstruction only by nerve transfers for restoration of function. Injury distal to the DRG are termed postganglionic, and these injuries occur as a spectrum of severity as described by the Sunderland classification. The most common injury pattern is a postganglionic injury involving the upper trunk (C5 and C6, or Erb’s palsy, 46%), potentially in combination with injury to C7 (extended Erb’s palsy, 29%). Less often, the lower trunk (C8 and T1) or the entire plexus (C5-T1 or global palsy) is injured. Pan-brachial plexus injuries are often a combination of preganglionic (avulsions) and postganglionic (stretch or varying degrees of rupture) injuries.

Grahn et al. performed a prospective study to evaluate if MRI improves patient selection for operative intervention in patients with BPBIs. They reported cervical MRI was performed on 34/157 patients at a median age of 3.9 months, and total root avulsions were detected on MRI in 12 patients. The sensitivity and specificity of MRI in detecting root avulsions were 0.88 and 1, respectively. They concluded that complete avulsion(s) on MRI is a good indicator for nerve surgery BPBI, as shoulder pathology develops very early in permanent BPBI.

Wells et al. performed a systematic review evaluating the trends in early surgical management of BPBI over the last 30 years. They reported that there has been a significant increase in the proportion of patients treated with primary nerve transfer procedures over time. They concluded that although neuroma excision and sural nerve autografting have been the historic gold-standard treatment for brachial plexus birth injury (for postganglionic injuries), peripheral nerve transfers have become increasingly utilized for surgical management (for post- and preganglionic injuries).

Figure A is a coronal MRI demonstrating nerve root avulsion with psuedo-menigocele formation (asterisk). Figure B is an axial MRI image of the C6 nerve root demonstrating both ventral and dorsal roots avulsion. The left ventral and dorsal C6 roots (arrowheads) are normal.

Incorrect Answers:
Answers 1 and 3: The timing of surgical intervention for POST-ganglionic nerve injuries is still debated, and if this patient did not have evidence of a nerve root avulsion (i.e. pre-ganglionic injury), then it may be reasonable to observe for spontaneous recovery of elbow flexion for an additional 3-6 months. While it has been accepted that patients who fail to recover active elbow flexion at 3 months of age subsequently fail to regain normal shoulder function and thus are indicated for surgical intervention, the timing of intervention is controversial.
Answer 2: This patient has a pre-ganglionic nerve injury involving C6, which means the spinal nerve root was avulsed directly from the spinal cord. Hence, there is no potential for spontaneous recovery, and these injuries require reconstruction only by nerve transfers for restoration of function.
Answer 5: The most common lesion found in patients with BPBI is a neuroma-in-continuity, which represents a post ganglionic lesion (Sunderland Type III and IV axonotomesis). Nerve grafting after neuroma resection is often necessary as low-tension neurorrhaphy after neuroma resection is rarely possible. While this patient may have a post-ganglionic injury involving C5 or C7, nerve root avulsions are not amenable to this treatment as there is no chance for axonal regrowth since the axons from C6 were avulsed directly from the spinal cord.