H-reflex Responses to High-Velocity Low-Amplitude Manipulation
Condition: Low Back Pain
MeSH terms: Back Pain; Low Back Pain
Study type: Interventional

Summary: 
      High-Velocity Low-Amplitude (HVLA) manipulation is a known technique of the Osteopathic
      Manipulative Treatment (OMT) for somatic dysfunction (SD), and heart rate variability and
      H-reflex response are possible variables to assess its neurophysiological effects. Somatic
      dysfunction is an impairment or altered function of related components of the somatic system.

      Studies show a transient attenuation of α-motor neuron excitability after HVLA manipulation
      in asymptomatic participants. According to studies, HVLA spinal manipulation increases joint
      mobility by blocking afferent impulses in the muscle spindle and the small-diameter free
      nerve, decreasing the γ-motor neuron activity.
    

Detailed description: 
      Osteopathic Manipulative Treatment (OMT) is a health science that addresses treatment to
      somatic dysfunction among other conditions. High-Velocity Low-Amplitude (HVLA) manipulation
      is a known technique, defined as a quick and short force applied to a segment with movement
      restriction.

      Somatic Dysfunction (SD) is the impaired or altered function of the components of the somatic
      system: skeletal, articular and myofascial elements with their vascular, lymphatic and neural
      related structures. The palpatory diagnosis of the SD is based on the presence of any of the
      4 TART (Tenderness, Asymmetry, Range of motion and Tissue texture change) criteria, taking
      into account the information provided about pain and discomfort.

      There is no evidence to support the use of the term 'somatic dysfunction' and moreover, the
      diagnosis is based on palpatory skills. Therefore, the investigators chose the term
      Restriction of Movement (RM) to describe the subjectivity of the palpatory examination.

      HVLA manipulation produces neurophysiological and mechanic effects. The mechanical effects
      described in the literature are: meniscoids release, intervertebral disc material and
      segmental adhesions. The neurophysiological effects occur through the stimulation of
      mechanoreceptors and nociceptors located in the paravertebral tissues, including the skin,
      muscles, tendons, ligaments, zygapophyseal joints and intervertebral discs. This changes the
      influx of sensory information into the Central Nervous System (CNS), and this effect can be
      measured by the H-reflex (reflex analogous to the spinal stretch reflex). Thus, this is a
      valuable tool in the assessment of α-motor neuron excitability.

      Studies show a transient attenuation of α-motor neuron excitability after HVLA manipulation
      in asymptomatic participants. According to studies, HVLA spinal manipulation increases joint
      mobility by blocking afferent impulses in the muscle spindle and the small-diameter free
      nerve, decreasing the γ-motor neuron activity.

      Most of the studies analyzed recruited healthy participants, and have found transient
      attenuation of α-motor neuron activity; but one study found that the manipulation does not
      affect the H-reflex in healthy participants. These authors attributed the findings to the
      change of position between intervention and assessment. In addition, the intervention was
      addressed to sacroiliac joint instead of the L5-S1 segment, as performed in other previous
      studies.

      Another study assessed the effects of manipulation without changing participants' position,
      but unlike the study of Suter et al., the intervention was addressed to the lumbosacral joint
      (L5-S1) and they concluded that changing body position does not affect the H-reflex
      attenuation.

      Therefore, the studies show divergent results for HVLA manipulation and H-reflex response,
      and to better understand the research problem, the investigators conducted a previous study
      in 20 healthy participants to assess the effects of HVLA manipulation on H-reflex and they
      found a transient H-reflex attenuation only in six participants.

      These findings could have been affected by the presence of RM at the level L5-S1 and also by
      the presence of dysfunction of the Autonomic Nervous System (ANS), which is processed at
      medullar level and runs along neural pathways, similar to somatic afferent and efferent
      information.

      To quantify ANS activity, one could use Nerve-Express - a device to assess heart rate
      variability based on RR (rate-rate) intervals. This method is used because of the major role
      the ANS plays on the cardiovascular system. Studies have shown the effects of cervical and
      lumbar HVLA manipulation on heart rate variability and on balancing the ANS.
    

Intervention name(s): HVLA manipulation; Sham Spinal lumbar manipulation
Intervention type(s): Other; Other
Intervention description(s): participant is laying on the left side, the practitioner stands in front of the participant's abdomen. The practitioner contacts the interspinous space of the L5-S1 level with the caudal; with the cephalic hand, the practitioner rotates the participant's upper body until a sense of tension is palpated at the L5-S1 segment. The practitioner places his cephalic hand at interspinous, brings participant's leg to a flexion and places the foot at the popliteal fossa, places the forearm at the participant's deltopectoral groove and the caudal forearm at the gluteal region. Following the participant's expiration, the practitioner brings the L5-S1 level to the restrictive barrier by rotating the trunk and hips to opposite directions.; Sham manipulation
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Double (Investigator, Outcomes Assessor)
Primary purpose: Treatment
Keywords: chronic low back pain; HVLA manipulation