Impact of Epidural Anesthesia on Low Back Function
Condition: Low Back Pain, Mechanical
MeSH terms: Low Back Pain
Study type: Observational

Summary: 
      Back pain is a common complication after the use of epidural anesthesia in obstetric and
      non-obstetric surgeries and occurs in 30-45% of cases (Brown, 2005). Certain psychological
      problems such as depression or unhappiness due to loss of employment may prolong the episode
      of low back pain (Miller, 2012). According to Egyptian Institution of Health Metrics and
      Evaluation (IHME), Low Back Pain is the first cause of disability in Egypt from 2007 to 2017.

      So, this study will investigate if midline approach of obstetric epidural anaesthesia will be
      a relative risk for subacute low back mechanical functions as a new way to examine if this
      type of anaesthesia is involved in the presence of subacute negative effects on the
      mechanical function of low back or not (to resolve the controversy).
    

Detailed description: 
      The lumbar (or lower back) region is made up of five vertebrae (L1-L5), sometimes including
      the sacrum. Stability of the spine is provided by the ligaments and muscles of the back and
      abdomen (Floyd and Thompson, 2008).

      The primary biomechanical function of the spine is to provide structural support, to allow
      the body to move freely, and to protect the spinal cord and nerves. Muscles balance external
      loads to the spine, which supports the load and allows for the motion through its multilevel
      joint arrangement (Dreischarf et al., 2016).

      Low back pain (LBP) is a common minor yet unpleasant complication after epidural anesthesia.
      Different mechanisms are suggested such as needle trauma and myotoxicity of local anesthetic
      (Louizos et al., 2005) and incidence of backache after epidural anaesthesia might be expected
      to be higher than that after spinal anaesthesia (Brown and Elman, 1961).

      In most episodes of low back pain, a specific underlying cause is not identified or even
      looked for, with the pain believed to be due to mechanical problems such as muscle or joint
      strain (Casazza, 2012). Most cases are idiopathic but usually attributable to muscle strain
      or ligament injury; found in 65% to 70% of patients with mechanical chronic back pain (Cohen
      et al., 2008) while totally mechanical low back pain is reported as the cause in about 80% to
      95% of patients with low back pain (Cohen et al., 2008) & (Dixit, 2017).

      Caesarean section is when a baby is born through an incision in the mother's abdomen and
      uterine wall. This requires effective anaesthesia which can be regional (epidural or spinal)
      or a general anaesthetic. With regional epidural anaesthesia, the anaesthetic is infused into
      the space around the mother's spinal column, whilst with regional spinal anaesthesia, the
      drug is injected as a single dose into the mother's spinal column. With the two types of
      regional anaesthesia, the mother is awake for the birth but numbed from the waist down while
      with general anaesthesia, the mother is unconscious for the birth with the anaesthetic
      affecting her whole body (Afolabi and Lesi, 2012).

      The epidural needle can be placed using the midline or paramedian approach. In both cases,
      lidocaine 1% is infiltrated in the epidural needle insertion area.

      In the midline approach technique, the needle is placed in the midline between 2 spine
      processes. In the paramedian approach technique, the needle is inserted 1 cm lateral and 1 cm
      caudal to the lower border of the upper spinous process.

      The epidural needle in the medline approach is advanced through ligaments: supraspinous
      ligament, interspinous ligament, ligamentum flavum and into the target epidural space. Each
      ligament has different density and texture, which affects the feel of the needle and the
      resistance to insertion (Vaughan et al., 2013).

      Some explanations for Low Back Dysfunction after Epidural Anaesthesia:

      The incidence of back pain after epidural anesthesia is over 20% (Rose, 2012) & (Saghafinia
      et al., 2009) & (Muslu et al., 2009). It occurs rarely after spinal anesthesia (Schwabe and
      Hopf, 2001). This indicates that back pain may be associated with local trauma and nerve
      injury caused by the epidural needle, leading to aseptic periosteitis, tendonitis,
      ligamentous inflammation and/or osteochondritis, which result in lumbar pain (Kalso, 2013).

        -  Excessive elongation of spinal ligaments can cause micro-trauma of the ligament fibers
           and tears or ruptures occur. Also, the interspinous ligaments are the first structures
           damaged (excessive stretching) when the spine is hyperflexed (Adams et al., 1998).

        -  Degeneration and excessive stress on the thoracolumbar fascia may also cause
           micro-trauma, and resulting in tears. Thoracolumbar fascia may become damaged by
           over-stretching or excessive stress, potentially eliciting pain (Bogduk, 1983).

        -  Other contributing factors include needle trauma, surgical positioning, injection of
           saline or local anesthetic into the interspinous ligaments and development of a
           supraspinous hematoma (Covet et al., 1967), (Crawford, 1972).

        -  Excessive stretching of ligaments after relaxation of paraspinal muscles and localized
           trauma to the intervertebral disc has also been implicated in causing back pain (Agarwal
           and Kishore, 2009).

      Visual analogue scale (VAS):

      The visual analogue scale is a validated, subjective measure for acute and chronic pain.
      Scores are recorded by making a handwritten mark on a 10-cm line that represents a continuum
      between "no pain" and "worst pain." (Delgado et al., 2018).

      Pressure algometry:

      Pressure algometry has been described as a semi-objective method, or subjective measure and
      Pain Pressure Threshold (PPT) is a quantitative sensory test of tissue sensitivity, and it is
      defined as the minimal amount of pressure that produces pain, measured via a pressure
      algometer (Ylinen, 2007).

      Inclinometers:

      An inclinometer or tilt meter is an instrument for measuring angles of slope (or tilt),
      elevation or depression of an object or body segment with respect to gravity (Nielsen et al.,
      2011).

      Oswestry Disability Index:

      The Oswestry Disability Index (ODI) is a valid, reliable, and responsive condition-specific
      assessment tool that is suited for use in clinical practice. It is easy to administer and
      score, objectifies clients' complaints, and monitors effects of therapy (Vianin, 2008).

      Isokinetic dynamometry:

      The isokinetic dynamometer is a gold standard instrument for measuring muscle strength and is
      safe, valid, and reliable, based on the use of kinetic parameters that also include the
      angular measurement of a corporeal segment throughout the range of motion (Gonosova et al.,
      2018) & (Habets et al., 2018) & (Roth et al., 2017) & (Guilhem et al., 2014).

      Ultrasound Elastography:

      Ultrasound elastography (EUS) is a recently developed ultrasound-based method, which allows
      the qualitative visual or quantitative measurements of the mechanical properties of tissue
      (Hall, 2003), (Garra, 2007) & (Garra, 2011).

      Myoton Pro Device:

      A MyotonPRO (Myoton AS, Estonia) is a portable hand-held myotonometer that can assess muscle
      tone and soft tissue stiffness. According to prior research, the MyotonPRO is a reliable
      quantitative measurement for assessing the mechanical properties of muscles (Pruyn et al.,
      2016).

      The MyotonPRO can differentiate the viscoelastic properties of a trigger point from a
      non-trigger point. Our findings support the reliability of this myotonometer. This affordable
      and portable tool can be used to objectively measure viscoelastic properties of trigger
      points (Roch et al., 2020).
    

Observational model: Cohort
Time perspective: Retrospective
Sampling method: Probability Sample
Study population: 
        45 women were enrolled in this study with a 20% rate loss of follow-up (i.e. we need at
        least 38 participants to complete the study). They were selected from the SVU Teaching
        Hospitals.

        The Participants were classified into 4 groups: -

        Group (A):

        This group included 6 women. They gave birth through a cesarean delivery using Midline
        approach epidural anesthesia,

        Group (B):

        This group included 13 women. They gave birth through a cesarean delivery using Midline
        approach spinal anesthesia

        Group (C):

        This group included 7 women. They gave birth through a cesarean delivery using general
        anesthesia.

        Group (D):

        This group included 12 women. who are the control group,