Frisbie and Sharma1 draw attention to the risk factor of pulmonary embolism following an acute spinal injury. They state that it is generally considered to be rare beyond the first 3 months of paralysis and that the concept has grown that chronic spinal injuries develop some protection from pulmonary embolism after 3 months. They reviewed the literature through a PubMed survey and made a study of 27 relevant articles.

We have been interested in the incidence and prevention of pulmonary embolism since 1970.2 Initially we had considered that pulmonary embolism did not occur after 3 months and therefore gave anti-coagulant therapy for this period. In 1981, Masri and Silver3 made a study of 102 consecutive male traumatic spinal cord injury patients admitted between 1976 and 1979 and recorded 2 patients who had a pulmonary embolism after 90 days and 129 days after injury. In view of this high risk, we extended the regime of anticoagulants to 6 months for patients with an established high-risk factor that is, those patients who had a massive deep vein thrombosis or a pulmonary embolus prior to admission to the centre.

The problem was re-examined in 1991 after Silver and Noori4 became aware of five patients, not all under their care, who had had a pulmonary embolus more than 90 days after injury. All had received a full course of therapeutic anticoagulation with oral anticoagulants for periods from 49 to 90 days. All five patients developed pulmonary emboli, two of which were fatal, at a period greater than 90 days after injury and despite having had a course of anticoagulation. These cases reinforced our view that there is a need to continue prophylactic anticoagulant therapy for a longer period in high-risk patients those with obesity, previous deep vein thrombosis and pulmonary embolus. This experience is not unique as Perkash5 in 1978 also demonstrated late pulmonary emboli more than 90 days after injury.

It is not surprising that patients develop deep vein thrombosis since Todd et al.6 in 1976 showed by fibrinogen leg scanning that all patients in a series developed deep vein thrombosis in their lower limbs after a spinal cord injury.

Moreover, in 1968, Morrell and Dunhill7 showed that all patients who died after admission to hospital had sub-clinical evidence of pulmonary emboli.

Frisbie and Sharma’s article is to be welcomed in drawing attention to a well-documented problem.