EMG, MRI, Arteriogram


Clinical Examination

Clinical examination is of paramount importance since it can be an easy way to overview of the lesion with a high degree of accuracy (number of roots involved and level of nerve lesions).
The examination of muscle function is the first fundamental step with special regards of proximally innervated muscles as Serratus muscle or Rhomboid muscles which can help to detect possible avulsion of the upper roots.
The presence of a Cl. Bernard-Horner sign can lead to the diagnosis of a quite sure avulsion of lower roots.

Examination of sensation in the different territory of the arm is very important to help to determine the level of lesions.
Other clinical examinations include the study of the possible associated bone and joint lesions which can help from one side assessing the level of nerve lesions and from the other side allow to predict the limits of the possible functional recovery. For the same reasons is very important to evaluate the vascular conditions of the arm assessing the radial pulse in absence of which an arteriogram or Doppler study are indicated. This will be useful to evaluate the condition of the muscles we are planning to reinnervate in order to modify where necessary the strategy of repair. Moreover knowing the anatomical conditions of the vessels (interruption of subclavian or axillary artery and presence of a collateral vascularisation) is of paramount importance for a safe reconstructive surgery.

Pain is another clinical sign to take into account. Quite constantly root avulsions are associated to severe pain, mainly referred to the hand since the lower roots are mostly avulsed.
This pain is therefore an indirect sign of root avulsion and, since it may frequently reach unbearable levels for the patient, it needs to be treated as early as possible in specialized pain clinics.

Instrumental examination

X ray are useful to detect sequelae of skeletal injuries that can interfere with plexus repair (callus on the clavicle) or to suggest a double level lesions (fracture of the scapula for suprascapular nerve, head of the humerus for axillary nerve and diaphysis of the humerus for radial nerve).
Fracture of transvers processes of the spine is normally associated to very proximal root lesions. A radiological study of diaphragm function is mandatory to detect possible lesions of phrenic nerve that can be associated with avulsion of C5 root.
The huge improvement in imaging given by 3D MRI allowed in the last years to detect with a high level of precision root avulsions. MyeloTAC still gives a good support in diagnosing preganglionic lesions.

Electrophysiological studies may give an important support in the diagnosis of the level of lesions but unfortunately even the evoked potential studies cannot precisely detect a preganglionic lesion that is the crucial point in brachial plexus lesions. Anyway EMG may be useful in the first months after injuries to eventually detect possible spontaneous recovery.

In presence of vascular lesions with lack of radial pulse it is important to study the vascularization of the arm through Doppler exam. or arteriograms mainly to know the exact definition of the collateral vessel formation; this will be of paramount importance during the surgical dissection of the plexus in order to avoid reducing the vascular support to the arm.

MRI can nowaday precisely detect not only the root avulsion (C8 and T1 in this case) but even mild irreguarity of the roots (C7 in this case) giving useful information about the quality of the root stumps.