Bjerkefors et al.1 have carried out a study on the role of the abdominal muscles below the level of a complete cord transection. This has long proved a source of mystery, so much so that as they point out, there is no established clinical method for examining motor function in the abdominal muscles following a spinal cord transection. Paradoxically, clinically it has been observed that these muscles appear to have some function and activity but what is the nature of this and how is it elicited? Bjerkefors et al. have endeavoured to answer this question.

The aim is to determine whether the muscle responses are voluntary and not simply a global activity that could be attributed to changes in intra-abdominal pressure, spasticity or stretch reflexes. They have endeavoured to rule out increases in intra-abdominal pressure as a main factor in activating this apparent contraction by studying electromyography (EMG) activity in 13 patients with cervical cord transections. Eleven patients had complete lesions but two had incomplete lesions of the spinal cord. They used surface electrodes but there was no recording of the ventilatory activity or recordings of the diaphragm or intra-abdominal pressure. They studied the patients with an open glottis and they say that the mechanism of this activation is unknown. They speculated that it was due to preservation of the cortico-spinal tract and that all the lesions were thus incomplete.

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