Use the fiber type pattern and symptom distribution to decide whether the process is focal, multifocal, or length-dependent. Reflex loss, sensory level, and distal weakness usually determine the next test.

A-beta fibers transmit touch and pressure; A-delta fibers carry fast pain and temperature; C fibers carry slow pain, temperature, and autonomic signals; Mononeuropathy affects one nerve; Polyneuropathy is usually symmetric and length-dependent