Application of short-segment nerve conduction studies in the cubital tunnel syndrome

Objective To evaluate the value of the short-segment nerve conduction studies (SSCSs，inching test) in the diagnosis and localization of cubital tunnel syndrome (CubTS). Methods The clinical and electrophysiologic data of 46 patients (92 limbs from 32 men and 14 women, aged from 19 to 59 years, with average age of 41.2 years) with CubTS were collected.The symptoms occurred in unilateral arm in 41 patients and bilateral arms in 5 patients, involving 35 left arms and 16 right arms.SSCSs were performed in both arms in all the 46 patients.Sixty ulnar nerves were studied in 30 healthy control subjects using SSCSs. Results The 51 symptomatic arms with CubTS were abnormal in long segment motor nerve conduction studies.There were 68 abnormal arms (51 symptomatic arms, 17 asymptomatic arms) in SSCSs.The lesions were located 2 cm proximal to the elbow-the elbow segment (AE2-E) in 41 arms (44.6%）,the elbow-2 cm distal to the elbow segment (E-BE2) in 23 arms （25%）, 4 cm proximal to the elbow-2 cm proximal to the elbow segment (AE4-AE2) in 18 arms （19.6%）, 6 cm proximal to the elbow-4 cm proximal to the elbow segment (AE6-AE4) in 9 arms （9.8%）, 2 cm distal to the elbow-4 cm distal to the elbow segment (BE2-BE4) in 8 arms（8.6%）and 4 cm distal to the elbow-6 cm distal to the elbow segment (BE4-BE6) in 6 arms（6.5%）,respectively. Conclusions SSCSs are more sensitive in detecting CubTS than the conventional long segment motor conduction studies.SSCSs could precisely localize the entrapment lesions in patients with CubTS,might be a useful tool for the detection of ulnar mononeuropathy at the elbow, especially for diagnosing the patients with CubTS who have no clinical features or have a normal long segmental nerve conduction findings. Key words: Cubital tunnel syndrome; Ulnar nerve; Nerve conduction; Electrophysiology