Intrathecal Morphine on Transcranial Electric Motor-Evoked Potentials
Condition: Trauma, Nervous System
MeSH terms: Trauma, Nervous System
Study type: Observational

Summary: 
      Patients undergoing posterior spinal fusion (PSF) procedures for scoliosis are at risk for
      iatrogenic neurologic injury of the spinal cord and/or spinal nerve roots during surgical
      correction of the abnormal spinal curvature. The degree of neurologic injury can range from
      minor sensory deficits to complete paraplegia. Surgeons at CHOP utilize neurophysiologists to
      identify impending neurologic injury. These consultants monitor spinal cord pathways by
      recording and analyzing evoked potentials during the operation. Evoked potentials are low
      voltage electrical signals generated in response to transcranial or transcutaneous electrical
      stimulation of motor and sensory neural pathways.

      Some patients undergoing PSF receive an injection of morphine into the cerebrospinal fluid
      during the operation. This intrathecal (IT) morphine has potent analgesic effects. While most
      commonly used anesthetic agents have well-characterized effects on evoked potentials, little
      data exists on the effects of IT morphine on transcranial electric motor-evoked potentials
      (TceMEPs).

      This is a prospective observational study to characterize the effects of IT morphine on
      TceMEPs.
    

Detailed description: 
      Posterior spinal fusion surgery (PSF) is associated with significant postoperative pain.
      Numerous postoperative pain management strategies have been employed for patients undergoing
      these procedures, including continuous narcotic infusions, intravenous patient-controlled
      opioid analgesia, epidural analgesia, intrathecally administered narcotics, and combinations
      of these regimens. Most patients at CHOP have their pain managed with intravenous
      patient-controlled opioid analgesia alone or in combination with a single dose of
      intra-operatively administered intrathecal (IT) morphine.

      Patients undergoing spinal fusion procedures are also at risk for perioperative neurologic
      injury. Surgeons at CHOP and other institutions routinely utilize neurophysiologists to
      evaluate at-risk neural pathways to identify impending spinal cord and spinal nerve root
      injury. These consultants monitor motor and sensory pathways by recording and analyzing
      evoked potentials and electromyography during the operation. Evoked potentials are low
      voltage electrical signals generated in response to transcranial or transcutaneous electrical
      stimulation of motor and sensory nerves.

      At CHOP, IT morphine is injected by the surgeon after the scoliotic curvature has been
      corrected and spinal instrumentation is complete. This injection therefore occurs after the
      critical period for neurophysiologic monitoring and risk of spinal cord injury. It is
      injected after the neurophysiologist has given a reassuring assessment of neural integrity.
      This injection is given to patients who have spinal fusions extending below the second lumbar
      vertebral body. Injections are limited to this group of patients because the appropriate
      intervertebral spaces for intrathecal injection are not exposed in procedures that do not
      extend below this level.

      Most commonly used anesthetic agents have well-characterized effects on evoked potentials.
      The effects of IT morphine on sensory-evoked potentials have been studied. However, little
      data exist on its effects on transcranial electric motor-evoked potentials. This study aims
      to characterize these effects; we hypothesize that intrathecal morphine has no effect on
      transcranial electric motor-evoked potentials in the doses used at our institution.
    

Intervention name(s): Intrathecal Morphine
Intervention type(s): Drug
Intervention description(s): In the IT morphine group, prior to IT morphine injection (within 15 minutes of the injection), the neurophysiologist will be asked to obtain a set of TceMEP recordings. The recordings collected at this time will be labeled "Baseline." These will serve as controls for subsequent recording comparisons.
In the IT morphine group, the time of IT morphine injection will be recorded, as well as the dose. A timer will be started. The neurophysiologist will then be asked to collect four additional sets of TceMEP recordings, at 5, 10, 20, and 30 minutes after morphine injection.
Intervention MeSH terms: Morphine
Observational model: Case-Control
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Children ages 11-18 with idiopathic scoliosis who are scheduled to have a posterior spinal
        fusion.
      
Keywords: Injections, intrathecal; Transcranial; Spinal Fusion; Evoked Potentials, Motor