Electromyographers are occasionally called on to evaluate the proximal nerves in the shoulder and arm. Isolated lesions of these nerves, including the suprascapular, axillary, musculocutaneous, long thoracic, and spinal accessory, are far less frequent than the common entrapment and compressive…
The brachial plexus is a complicated anatomic structure formed by the ventral rami of the lower cervical and upper thoracic nerve roots. Different fascicles from those roots intermix widely within the plexus to ultimately form all the nerves of the…
Radiculopathy is one of the most common diagnoses referred to any electromyography (EMG) laboratory. Even with the widespread use of magnetic resonance imaging, EMG continues to play an important role in the evaluation of radiculopathy. Although imaging studies usually are…
There are a heterogeneous group of motor neuron disorders that are rare but nonetheless important to recognize because they often mimic the presentation of amyotrophic lateral sclerosis (ALS). These often are referred to as atypical motor neuron disorders . They…
Electrodiagnostic (EDX) studies play a central role in the evaluation of patients with amyotrophic lateral sclerosis (ALS), the most common of all motor neuron disorders. Although described earlier by others, the French neurologist Jean-Martin Charcot is credited as naming the…
Nerve conduction studies (NCSs) and electromyography (EMG) play key roles in the evaluation of patients with suspected polyneuropathy. Although polyneuropathy has hundreds of potential causes, they can be grouped into several large categories ( Fig. 29.1 ). The first step…
Although nerve conduction and electromyography (EMG) studies are used most often to evaluate peripheral nerve and muscle disorders, they can also be used to evaluate lesions of the cranial nerves. Outside of the brainstem, the cranial nerves, other than cranial…
Patients with pain and numbness in the foot often are referred to the electromyography (EMG) laboratory for evaluation of possible tarsal tunnel syndrome (TTS). TTS results from entrapment of the distal tibial nerve under the flexor retinaculum at the medial…
Isolated lesions of the femoral nerve are uncommon in the electromyography (EMG) laboratory. More common are lesions of the lumbar plexus or L2–L4 nerve roots, which may present with symptoms and signs similar to femoral neuropathy. Especially in milder cases,…
Peroneal neuropathy is one of the most common mononeuropathies in the lower extremity. Most often, peroneal neuropathy occurs at the fibular neck, where the nerve is quite superficial and vulnerable to injury. Patients usually present with a foot drop and…