Anticoagulation in Paraplegic Patients

My 45-year-old paraplegic patient had deep venous thrombosis (DVT) of the thigh 6 months ago and has been taking warfarin since. This was his first and only episode of DVT. How long should he continue to receive warfarin?

— Ivanka Vassileva, MD
  Lawton, Okla

The role of anticoagulation in the treatment of patients who have been permanently immobilized as a result of neurological impairments is unique. Patients with spinal injuries have been comprehensively studied, and the data are very clear: the risk of DVT falls sharply 4 to 6 months after the injury and onset of immobility.^1,2 Two mechanisms are proposed for this sharp decline:

• The arterial atrophy that accompanies the low demand for oxygen by the paralyzed limbs; this arterial atrophy is accompanied by venous atrophy, with subsequent paradoxical improvement in blood stagnation in the lower limbs, which prevents further DVTs.
• The development of high muscle tone, which is often associated with frequent muscle spasms; this can improve the calf muscle pump.

This means that your patient, in whom DVT developed because of sudden immobility, will have physiological changes within 4 to 6 months that will protect him against further DVTs. Thus, a 6-month anticoagulation regimen should be sufficient for him.

Note that if DVT develops despite prophylactic anticoagulation, the patient must be screened for coagulopathies. If the results are positive, appropriate treatment should be implemented; consider surgical management, using procedures such as placement of a vena cava filter. If the results are negative, the patient should be offered life-long anticoagulation; he or she most likely has a strong susceptibility for thrombosis.

— Tarek Gaber, MD
  Greater Manchester Neuro-rehabilitation Network
  Lancaster
  UK