[Microsurgical drezotomy for the treatment of spasticity of the lower limbs]

Ablative functional neurosurgery can be useful in some selected patients for the treatment of harmful spasticity in the lower limbs. Microsurgical drezotomy was introduced in 1972, on the basis of anatomical studies of the human dorsal root entry zone (DREZ) showing a topographical segregation of the afferent fibers according to their size and thus functional destinations. It consists of a 3 mm deep microsurgical lesion directed at a 45 degree angle in the postero-lateral sulcus, penetrating the DREZ in its ventro-lateral aspect, at the level of all the rootlets considered as involved in spasticity (and pain). It destroys mainly the lateral (nociceptive) and central (myotatic) afferent fibers as well as the facilitatory medial part of the Lissauer tract, whilst sparing most of the medial (lemniscal) fibers and the inhibitor lateral part of the Lissauer tract. We report a series of 121 bedridden patients suffering from harmful spasticity in one (15) or both (106) lower limbs and treated with microsurgical drezotomy. Surgery was decided on because of abnormal postures in flexion in two-thirds of the patients and in hyperextension in one-third, additional pain in 75 of them, and hyperactive bladder in 38 cases. The post-operative results were evaluated after a mean follow-up time of 5 years and 6 months. Both spasticity and spasms were significantly decreased or suppressed respectively in 78% and 88% of the patients. When present, pain was relieved without abolition of sensation in 82%. These benefits resulted in either disappearance or marked reduction of the abnormal postures and articular limitation in 90% of the patients. When present preoperatively, urinary leakage disappeared in 85% of the cases. Mild to severe complications occurred in 32 patients and precipitated or were responsible for death in 6 cases (5%). This is explained by the fact that most of the patients, especially those affected by multiple sclerosis, were in very precarious general and neurological conditions. Microsurgical drezotomy has however enabled a large majority of these severely disabled patients to sit and lie comfortably, and allowed them to reach a significantly improved quality of life.