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A Pilot Study of the Test Characteristics of Physical Exam in Determining Ultrasound Presence of Myofascial Trigger Points

Author 1 Alasdair Rathbone H.BSc.Kin., Author 2 Liza Grosman-Rimon PhD, Author 3 Brian Vadasz, MSc, Author 4 Dinesh Kumbhare MD MSc

Institutional Affiliations

Author 1 University of Western Ontario, Schulich School of Medicine and Dentistry, Authors 2, 3 &4 University of Toronto, Department of Medicine Toronto Rehabilitation Institute-University Health Network

Context/Objective

Myofascial pain syndrome is a common pain disorder primarily diagnosed by history and physical exam. No sensitivity or specificity is known for physical exam because there has been no gold standard to compare it to. We propose a comparison to the presence of a trigger point on ultrasound.

Design

Cross-sectional diagnostic accuracy

Setting

Pain clinic at an academic medical centre.

Participants

10 patients both with and without neck pain.

Interventions

Physical examination of the upper trapezius for characteristics of trigger points, ultrasound of the upper trapezius, and administration of a VAS for pain and Neck Disability Index (NDI) for disability.

Outcome Measures

Sensitivity, Specificity, Negative and Positive Predictive Values (NPV and PPV) and Likelihood Ratios (-LR and +LR)

Results

8 subjects received US of both trapezius, with two subjects receiving US of one trapezius for a total of 18 necks. Best test performances were found for recognition of pain on palpation (Sensitivity 0.90 (0.55, 1.00), Specificity 0.62 (0.24, 0.91), PPV 0.75 (0.43, 0.95), NPV 0.83 (0.36, 1.00), +LR 2.40 (0.96, 6.01), -LR 0.16 (0.02, 1.11)), palpation of a taut band or nodule (Sensitivity 0.90 (0.55, 1.00), Specificity 0.50 (0.16, 0.84), PPV 0.69 (0.39, 0.91), NPV 0.80 (0.28, 0.99), +LR 1.80 (0.87, 3.71), -LR 0.20 (0.03, 1.45)) and localized tenderness (Sensitivity 0.90 (0.55, 1.00), Specificity 0.25 (0.03, 0.65), PPV 0.60 (0.32, 0.84), NPV 0.67 (0.09, 0.99), +LR 1.20 (0.76, 1.88), –LR 0.40 (0.04, 3.66).