MRI Diffusion Tensor Tractography to Monitor Peripheral Nerve Recovery After Severe Crush or Cut/Repair Nerve Injury
Condition: Nerve Injury
MeSH terms: Wounds and Injuries
Study type: Observational

Summary: 
      It is estimated that up to 5% of all admissions to level one trauma centers have a peripheral
      nerve injury. These peripheral nerve injuries may have devastating impacts on quality of life
      and require months or years to regain function. Neurotmesis, or peripheral nerve transection,
      is a common injury, with singly cut nerve lacerations accounting for over 60% of the
      peripheral nerve surgical interventions in civilian studies. For recovery to occur in these
      patients, axons must grow from the site of repair to the target tissues, a length of up to a
      meter in humans. By that time, revisional surgery may not be a viable option due to the onset
      of irreversible muscle atrophy - a transected nerve is estimated to induce a loss of
      achievable function of approximately 1% for every 6 days of delay. The scenario is even worse
      for more proximal nerve injuries, such as those that occur in the brachial plexus.

      The investigators aim is to longitudinally assess diffusion tensor tractography (DTI) in
      order to optimize, validate, and translate the ability of DTI to monitor and, more
      importantly, predict nerve regrowth following trauma and surgical repair. The overall
      objective of this study is to evaluate the ability of (DTI) to monitor and, more importantly,
      predict nerve regrowth following crush or cut with surgical repair. The investigators
      hypothesize that the additional information available via DTI will improve our ability to
      monitor and predict nerve regrowth following surgical repair or severe crush injury, guiding
      clinical management either toward or away from surgical intervention.
    

Detailed description: 
      Although nerve transfers can reduce the length of axonal growth required, failures still
      occur and revisions are rarely an option due to the aforementioned delays in detection.
      Current neurodiagnostics [e.g., electromyography (EMG), nerve conduction studies (NCS)] are
      of limited utility in severely damaged nerves, providing an incomplete picture of nerve
      microstructural features until target reinnervation occurs. Thus, physicians are limited to a
      "wait and watch" approach based on qualitative measures obtained from patient history and/or
      physical exam. This leads to a suboptimal management of peripheral nerve injuries, which in
      turn can lead to increased instances of irreversible muscle atrophy, paralysis, and/or
      formation of painful traumatic neuroma.

      In terms of the military, extremity injuries accounted for 54% of combat wounds in Operation
      Iraqi Freedom and Operation Enduring Freedom and recent review of service member injuries
      during Operation Enduring Freedom noted significant increases in brachial plexus, ulnar, and
      radial nerve injuries attributable to modern warfare. In addition, symptomatic neuroma occurs
      in 13% to 32% of amputees, causing pain and limiting or preventing the use of prosthetic
      devices. Take the example of a wounded warrior with a shrapnel injury to his/her elbow,
      resulting in the loss of an ulnar nerve segment. Even if nerve grafting is performed, true
      recovery (motor and/or sensory innervation of the hand) could take up to a year under typical
      circumstances. If the repair fails, which occurs in up to 40% of patients the failure is
      typically not truly recognized until that year expires using current management protocols. By
      that time, revisional surgery is typically not a viable option due to the aforementioned
      onset of irreversible muscle atrophy. In additional to an inability to effectively monitor
      nerve recovery after repair, diagnosis of peripheral nerve injuries is difficult using the
      currently available methods. For example, neurotmesis is a common, but difficult to
      distinguish, diagnosis following traumatic or iatrogenic extremity injury. Current
      electrodiagnostic and clinical examinations are invasive, time consuming, and painful. In
      addition, they cannot perfectly discriminate a severe axonotmetic laceration from a
      self-resolving neurapraxic injury in the acute setting. This is particularly important in
      penetrating injuries, or after iatrogenic nerve injuries resulting from nerve blocks, or from
      intraoperative positioning or external compression, because the degree of axonal injury is
      unknown.
    

Intervention name(s): MRI of 3.0T
Intervention type(s): Device
Intervention description(s): Diffusion Tensor Testing for peripheral nerve monitoring
Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        subjects between ages of 18 and 64 year of age diagnosed with a Sunderland Class V
        traumatic neuropathy (transection injury) of the upper extremity nerves that require
        immediate operative repair of this injury