Cervical spinal manipulation versus thoracic spinal manipulation on peripheral neural features and grip strength in subjects with chronic mechanical neck pain: A randomized controlled trial.

INTERVENTION: The sample included subjects with mechanical non‐specific NP, that were randomly distributed into three groups. The cervical group received a high‐velocity low amplitude (HVLA) spinal manipulation over the lower cervical spine (C7), the thoracic group underwent a HVLA spinal manipulation over the upper thoracic spine (T3), whereas the placebo group (PG) received a sham‐manual contact. Measurements were taken before intervention and immediately afterwards of the pressure pain threshold over the median, ulnar and radial nerves and free‐pain grip strength with a hydraulic dynamometer.The intervention performed a physiotherapist and lasted five minutes in a single session. CONDITION: mechanical neck pain neural mechanosensitivity PRIMARY OUTCOME: Pressure Pain Threshold (PPT) over the upper limb nerve trunks ; The PPT, as the primary outcome measure, was assessed with a digital dynamometer with compression force between 5‐20 kg, (PCE Instruments UK Ltd, Southampton), model FM200, and with a contact probe size of 1 kg / cm squared. Measurements were made alternatively on both upper limbs, starting with the right side. A increasing pressure of 1kg/cm squared was used, with a resting period of 30 seconds between measurements. The reference PPT score was the mean of three measurements in each spot. Subjects were instructed to tell the evaluator to stop when the sensation changed from pressure to slightly unpleasant pain. PPT was evaluated over the upper limb nerve trunks, with the subject lying supine, and in the following order: (a) median nerve, which was located in two diffferent sites. First, the nerve was located at the carpal tunnel site, lateral to the flexor carpi radials muscle. Second, the nerve was also marked in the ulnar fossa, medial to and immediately adjacent to the tendon of biceps brachii; (b) the ulnar nerve was palpated in the space between the medial epicondyle and the olecranon, once the elbow was previously flexed; and (c) the radial nerve, which was located in the humeral tunnel torsion, between the medial and lateral heads of the triceps brachii at the mid third of the humerus. Pressure algometry is a valid tool that has shown a high inter‐examiner reliability, ICC = 0.91 (95% CI 0.82‐0.97). The standard error of measurement (SEM) in healthy individuals ranges from 0.52kg / cm squared 0.64 kg / cm squared SECONDARY OUTCOME: Grip Strength (GS) INCLUSION CRITERIA: (a) age between 20 and 50 years old; (b) NP (grades I or II) of at least 12 weeks of duration; and (c) a positive response to the ULNT of the median nerve (ULNT‐1) in at least one upper limb. ; The pain‐free grip strength (GS) was evaluated with an isometric, hydraulic hand dynamometer (JAMAR registered trademark, mod 5030J1, Illinois, USA). Dynamometry is a reliable, reproducible and easy‐to‐use tool. Following the guidelines of the American Society of Hand Therapists, the subject was standing, with the shoulder adducted and neutrally rotated, arm and elbow along the body, elbow flexed to 90 degrees, forearm in the neutral position, and the wrist with a ‘subtle’ dorsal flexion and ulnar deviation, if needed, or in the neutral position. This procedure has shown an excellent test‐retest reliability, with ICC values ranging between 0.81 and 0.98. The subject was instructed to “squeeze the handle as strong as possible” without feeling pain or discomfort. Three measurements of 5 seconds each and with a 15‐second resting period between them, to prevent fatigue, were carried out, taking the mean as the reference value.