Traumatic spinal cord injury (Proceedings) - Veterinary Healthcare


Traumatic spinal cord injury (Proceedings)


     • Primary injury
          o Direct parenchymal and vascular damage
          o Occurs immediately as a result of traumatic event

     • Secondary injury
          o Result of biochemical cascades initiated by primary injury
          o Includes ATP depletion, increases in intracellular Na+ and Ca2+ as well as extracellular excitatory neurotransmitters, production of oxygen free radicals, increased cytokine production, accumulation of nitric oxide, lactic acidosis and activation of arachidonic acid, kinin, complement, coagulation and fibrinolytic cascades
          o Results in further damage to nervous tissue
          o Therapy directed at minimizing secondary injury

     • Initial neurologic evaluation
          o Important components of neurologic exam
               ▪ Motor/Posture – ambulatory vs. recumbent, muscle tone and voluntary movements, Schiff-Sherrington posture
               ▪ Segmental reflexes – tendon, withdrawal, panniculus and perineal reflexes
               ▪ Pain perception – assessed via behavioral response to a noxious stimulus
                     Superficial – elicited from pinch of the skin/SQ tissues
                     Deep – elicited from pinch of bone/digit
               ▪ Mentation and cranial nerve evaluation can generally be performed without significant patient manipulation
          o Scoring system has been described for acute spinal cord injury in dogs
          o Initial neurologic status may improve following immediate stabilization

     • Management of TSCI
          o Immobilization
          o Hemodynamic stabilization
               ▪ Resuscitation for maintenance of normotension, adequate oxygen levels
                     Often concurrent injuries involving other areas – cardiovascular, respiratory, abdominal, brain trauma
               ▪ CBC, chemistry panel, electrolytes, UA and thoracic radiographs can help define extent of injuries
          o Analgesia
          o Imaging
               ▪ Radiographs – screening lateral views safe; VD views only with a horizontal beam technique if potential for instability exists
               ▪ CT – excellent bone detail, evidence of hemorrhage may be seen
               ▪ Myelography – used to evaluate potential spinal cord compression
               ▪ MRI – for evaluation of extrinsic and intrinsic spinal cord lesions
          o Medical management to reduce secondary injury
               ▪ Corticosteroids
                     Use controversial in human and veterinary medicine
                     Methylprednisolone has been extensively evaluated; evidence suggests benefit related more to free radical scavenging than anti-inflammatory properties; other commonly used steroids (e.g. prednisone, dexamethasone) do not have free radical scavenging capabilities
                     National Acute Spinal Cord Injury Study trials in humans
                        o Small improvements (in motor scores at 6 weeks and pinprick and touch sensation at 6 months post injury) noted in TSCI patients administered methylprednisolone within 8 hours of injury; detrimental >8h; no difference in outcome vs. control groups at 1 year; increased risk of pneumonia and trend towards sepsis with methylprednisolone therapy
                     A study in dogs showed timely surgical decompression of acute compressive spinal cord injury was more effective for improving neurologic recovery than methylprednisolone without surgery
                     A study of dachshunds administered methylprednisolone and having surgical decompression following IVD herniation showed increased post-operative complications (melena, diarrhea, emesis, hematemesis and anorexia) and higher medical bills vs. dogs not receiving methylprednisolone Polyethylene glycol (PEG)
                     Use shown to be safe in dogs
                     Ongoing studies for evaluation of efficacy in spinal cord injury
               ▪ N-acetylcysteine has been investigated to prevent oxidative secondary injury in dogs, but did not prove to have clinical benefit in a randomized blinded placebo-controlled clinical trial


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