Neuropathy disability score (NDS) and neuropathy symptoms score (NSS)

A modified version of the clinical scoring system NSS and NDS was used to evaluate neuropathic symptoms and the severity of sensory deficits (23). The scoring system investigates the qualities of large and small nerve fibers (24). For the NSS, the presence of burning, numbness, paresthesia, weakness, cramps, and pain in feet or distal legs and its diagnostic relevance was weighted (range 0-3 points) as previously described (23). Exacerbations during day and night and improvement during movements were also considered. The maximum total score was ten points. Symptom classification was mild (3–4 points), moderate (5–6 points) or severe (7–10 points). Clinical examination for NDS included ankle tendon reflex, vibration, pin prick test and temperature sensation by cold tuning fork. All tests were performed on both sides. Normal reflex and sensory responses were scored zero (0), reduced or absent sensory responses were scored 1 for each side. A reduced or absent reflex was scored 1 and 2, respectively. The maximum total score was ten points. Minimum criteria for existence of distal symmetric DPN were: moderate clinical neurologic deficits (NDS 6–8 points) with or without symptoms, or mild clinical neurologic deficits (NDS 3–5 points) with at least moderate symptoms (NSS 5–6 points or higher). Hence, symptoms without sensory deficits in clinical examination were not sufficient for diagnosing a distal symmetric DPN.