Name: Daniela Rezende Frey

Institution: McGill University    
Email: daniela.frey@mcgill.ca

Project Title

The role of muscle spindles in chronic pain

Short Project Description

Recent studies have suggested that muscle spindles may be involved in the mechanisms of chronic pain. There is evidence that muscle spindles contribute to pain experienced after certain forms of exercises. Experiments in humans using vibration associated with local pressure and nerve block suggest that Delayed Onset Muscle Soreness of leg muscles is the result of activation of muscle spindle afferents, rather than sensitization of nociceptors. Moreover, the cell bodies of masseter muscle spindle afferents have intrinsic resonant properties that produce oscillations in their membrane potential and occasional firing. The oscillations increase in amplitude in an animal model of chronic jaw muscle pain, and this leads to repetitive firing. Similar abnormal oscillations and repetitive discharges in other types of sensory afferent neurons have been linked to the allodynia and hyperalgesia of neuropathic pain.

The objective of the present study is to assess the role of muscle spindles in chronic muscle pain in humans. It has been shown that the most important signs and symptoms related to chronic pain states can be induced experimentally by infusions of algesic chemicals into the muscles. In our study, hypertonic saline (5%) or acidic saline (pH 5.2) will be injected into the masseter muscle of healthy, pain-free volunteers. Hypertonic saline is known to induce deep aching similar to that experienced in clinical situations, whereas acidic saline induces a more long-lasting, mechanical hyperalgesia. During infusions of control (0.9% saline) and painful solutions, muscle vibration will be applied at regular intervals to activate muscle spindle afferents, and changes in the magnitude of pain will be assessed using a visual analog scale. We believe that these experiments may help to better understand the complex interaction between pain and motor systems, and to develop more efficient therapeutic strategies for chronic pain.

Academic Qualifications

DDS, Orthodontist - Federal University of Rio Grande do Sul, Brazil

Most Recent Publications

Frey DR, Hatch JP, Van Sickels JE, Dolce C, Rugh JD. Alteration of the mandibular plane for sagittal split advancement: short and long term stability. Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology (In press).

Frey DR, Hatch JP, Manning K, Nakatsuka K, Nakatsuka Y, Bhatt A, Rugh JD. Effects of an Intra-oral Jaw Tracking Magnet on Speech.  85th International Association for Dental Research Meeting, New Orleans, USA, March 21-24, 2007.

Frey DR, Hatch JP, Van Sickels JE, Dolce C, Rugh JD. Effects of mandibular advancement and rotation on signs and symptoms of temporomandibular disorder: a 2-year follow-up study (Under review).