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Chapter 7: Disorders of cranial and peripheral nerves 341

Lateral cord
Posterior cord C5
C6
Musculocutaneous C7
nerve C8
T1
Radial nerve
Median nerve
Ulnar nerve Medial cord
Figure 7.5 Anatomy of the brachial plexus.

Investigations Fig. 7.5). Lesions of the upper plexus (C5/6) cause Erb’s
The diagnosis is essentially clinical but can be confirmed palsy and lesions of the lower plexus (C8/T1) causes a
by EMG/ nerve conduction studies, which show slowing Klumpke’s palsy.
or blockage of conduction of nerve impulses. CSF analy-
sis may be normal initially, but usually protein levels are Aetiology
highafterthefirstweek.Serialforcedvitalcapacity(FVC) Trauma: By severe traction with the arm in abduction
measurement is necessary to monitor respiratory mus- (usually after a motorcycle accident), or penetrating
cle function. Oxygen saturations are of minimal value as trauma. Traction injury during a difficult labour may
they only fall late in respiratory failure. damage the brachial plexus most commonly causing
an Erb’s palsy.
Cervical rib: A bony or fibrous protrusion from the
Management
transverse process of C7 can stretch the lower roots of
Patients should have cardiac monitoring and in some

the brachial plexus.
cases may be admitted to an intensive care unit, if
Malignant infiltration.
ventilation is likely.
Intravenous immunoglobulin or plasma exchange re-

duces the duration and severity. They are generally Clinical features
Erb’s palsy (C5/6 lesions) with failure of abduction
used for moderate to severe cases (i.e. those who are
unable to walk without assistance, or who require ven- and external rotation of the arm. The arm is held in
tilation). adductionandinternalrotation(waiter’stipposition).
Klumpke’s palsy (C8/T1 lesions) The intrinsic mus-

cles of the hand are paralysed (ulnar nerve) resulting
Prognosis in wasting of the small muscles, a claw hand (flexor
Recovery though gradual over many months is usual digitorum muscles supplied by the median nerve) and
but is sometimes incomplete, leaving patients with distal
loss of ulnar sensation.
neurological symptoms such as paraesthesiae or foot- In atotal plexus lesion the entire arm is paralysed and
drop. Mortality is ∼5% despite intensive care. Prolonged
numb.
(>2months) of disability or recurrence should prompt Pain is characteristic of infiltration.
the search for another cause.
Investigations
Chest X-ray may show an apical lung lesion (Pancoast
Brachial plexus injuries
tumour)oracervicalrib.MRIisthemostusefulimaging
Definition to investigate brachial plexus lesions.
The brachial plexus is formed from the nerve roots of
C5–T1, which form into the medial, lateral and poste- Management
rior cords. These then form the median, ulnar, radial Treatment of the underlying cause. In traumatic in-
and musculocutaneous nerves supplying the arm (see juries open wounds should be explored and clean cut