PeripheralNerves.com

Obstetric Brachial Plexus Palsy (OBPP) 

Sub-topics

Introduction / Aetiology / Classification / Clinical Features / 

Diagnosis (Electrophysiology)  / Prognosis / Treatment / Surgery / 

Results / Late Effects of OBPP.

Diagnosis (Electrophysiology)

Early diagnosis of extent of lesion paves the way for early detection of lesions requiring surgery. Two percent children have bilateral involvement. Later examination is geared towards detecting secondary deformity. 

A differential diagnosis of condition mimicking OBPP like Birth fractures around the shoulder, Cerebral Palsy and arthrogryposis must be borne in mind.

Investigations like MRI scanning and myelography are used by some to detect pre-ganglionic avulsions which have a worse prognosis.

Neurophysiological Examination

Pioneering work has been done by Dr Shelagh Smith at the National Hospital for Neurology and Neurosurgery, London. She has been able to show a dense neuropraxia in 20% children with late recovery thereby preventing unnecessary surgery.

The NAP (nerve action potential) of the Median and Ulnar nerves are recorded from just below the elbow after stimulating at the wrist. 

1. If the amplitude is close to that of the normal side, it is either just a neuropraxia (conduction block) which has a good prognosis or it is a severe avulsion. If on further EMG sampling of C5 (deltoid), C6 (biceps), C7 (triceps or wrist extensors) and C8 (wrist flexor), there is fibrillation and no recruitment it signifies a avulsion. T1 EMG is difficult.

2. If the NAP amplitude is subnormal but >50% of normal and there are recruiting motor units then the lesion is termed favourable (axonotmesis) - there being no indication for exploration.

3. If the NAP amplitude is subnormal but <50% of normal and there are no recruiting motor units then the lesion is termed unfavourable (neurotmesis) - there being an indication for exploration.

Prognosis

Children with favourable lesions get a powerful grasp in 2 to 4 weeks. Elbow flexion and shoulder movements return in 6-8 weeks. Persisting paralysis at 3 months indicates a deep lesion. Groups 3 and 4 (Gilbert and Tassin) that do not show good recovery at shoulder and arm never regain worthwhile function.

Even though good functional recovery is sometimes seen, these children need to followed for late secondary effects on the shoulder particularly stiffness, dislocation or subluxation. These effects also lead to annoying winging of the scapula (surprisingly a number of sources mistakenly quote a paralysis of the long thoracic nerve as the cause).

Most of the children also show difference between the two upper limb lengths.

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Last modified: July 02, 2002