Motor Predominant Neuropathy Characteristics and Diagnosis

Introduction to Motor Predominant Neuropathy

Motor predominant neuropathy primarily affects large nerve fibers, as it involves the motor axons which are myelinated large fibers 1, 2
In severe cases, patients may present with distinct physical deformities such as hollow foot and stork legs 1, 2
Motor impairment is often associated with reduction or absence of deep tendon reflexes, distal weakness, atrophy of small feet muscles, tremor, and cramps 1

Affects myelinated Aα and Aβ fibers (large diameter) 3, 4
In sensory involvement, affects proprioception, vibration sense, and light touch 1
Electrophysiological studies show abnormalities in nerve conduction studies due to involvement of myelinated fibers 1, 2
Affects unmyelinated C and thinly myelinated Aδ fibers 3, 4, 5
Primarily involves nerve terminals responsible for temperature and pain perception 1
Presents with painful sensations like burning feet/hands and lancinating pain 1
Clinical examination reveals decreased pain perception and temperature sensation 1
May include autonomic symptoms (postural hypotension, bladder disturbances, reduced heart rate variability) 1, 5

Conventional neurophysiological methods (EMG with nerve conduction studies) are useful for diagnosing motor predominant neuropathies as they assess large fiber function 1
Motor neuropathies show reduction of compound muscle action potential (CMAP) amplitude correlating with axonal damage in EMG 1