--a small-fiber neuropathy would not produce motor symptoms of twitching, cramping, etc., as the small fibers are sensory or autonomic in function.

Having said that, though, the incidence of pure small fiber neuropathy is not as common as that of more mixed types, including those that are PREDOMINANTLY small-fiber, with all the symptoms that entails, and yet may have some motor components. This is often referred to as sensorimotor polyneuropathy, with the "sensori" designation first meaning, in medical-ese, the sensory components are dominant over the motor ones.

Also, don't underestimate the possibility of compressive effects in producing some motor symptoms, particularly twitching/cramping/fasiculations. It's not that hard to compress motor tracts in certain areas of the body in which nerves have to pass through narrow openings--elbow, wrist, shoulder, hip/thigh, knee, ankle--and anything from arthritic bone spurring to swelling from some other condition to biomechanical imbalance (including, oddly enough, building muscle unevenly!) might result in this. There is almost certainly some genetic tendency to this as well, as there is to developing bone spurs or disc bulging/herniation in the spine, which can itself pressure nerve roots and produce similar symptoms.

There are, unfortunately, really a LOT of ways to compromise nerves.