Myofascial Dysfunction in Post Stroke Shoulder Pain

Aim 1: Quantify the extent of HA accumulation in shoulder muscles using T1rho MRI before and after treatment with hyaluronidase injections versus placebo in patients with PSSP. Hypothesis: The primary objective will be to demonstrate that dysfunctional shoulder girdle muscles on the paretic side in patients with PSSP will show decreased T1ρ relaxation times in the infraspinatus muscle after treatment with hyaluronidase injections compared with placebo 5-7 weeks post-injection. Aim 2. Determine maximum sheer strain in shoulder muscles using US shear strain mapping before and after treatment with hyaluronidase injections versus placebo in patients with PSSP. Research Hypothesis: Shear strain on the paretic side in patients with PSSP measured using ultrasound shear mobility between the pectoralis major and minor muscles will decrease after treatment with hyaluronidase injections compared with placebo 5-7 weeks post-injection. Aim 3. Assess the impact of hyaluronidase injections compared with placebo on shoulder pain, pain free range of motion, upper limb motor impairment, function and quality of life in patients with PSSP. Hypothesis: Hyaluronidase injections compared with placebo in patients with PSSP will lead to (1) reduced pain as assessed using the pain questionnaires and lower pain-pressure thresholds with quantitative sensory testing using an algometer; (2) increased pain free range of motion in most affected shoulder joints; (3) reduced upper limb motor impairment measured using the Fugl-Meyer Scale; (4) increased function measured using the Wolf Motor Function Test; and (5) improved quality of life measured using the Stroke Specific Quality of Life scale.