Mesencephalic spinothalamic tractotomy (Dogliotti-Walker 1938—1942) has the same function as the above operation and belongs today to the group of difficult procedures, which are seldom carried out. It is very difficult because of lack of operative approach, small operative field, and the proximity of important anatomical structures (posterior cerebral and superior cerebellar arteries, venous sinuses, Labbe’s vein and the IVth and Xth cranial nerves) and requires very precise orientation. The approach to the operative field is attained by opening the skull posteriorly, and after reflection of the occipital portion of the hemisphere, a longitudinal incision is made on the lateral side of the brainstem, through the inferior collicula. The cut is 5 mm deep and 5 mm long (Plate VI). Zapletal, from the Department of Surgery in Olomouc, (1955) has suggested a more convenient approach from the posterior fossa.
To date there is relatively little experience with this operation; there are less than 50 cases in the literature. Neither weakness of the extremities nor urinary disturbances have been observed. However, homonymous hemianopsia, various parasthesiae and generalised dullness of sensation can result. The dangers of the procedure are obvious from the mortality. Of 28 cases operated on by 7 surgeons, 10 (35.7 %) died up to 23 days after operation. The 8 postmortems (2 were not done) showed that the cause of death directly resulted from the operation in 5 — haematoma, cerebral oedema and acute softening of the occipital cortex. The other 3 cases died of pneumonia.
I am of the opinion that this procedure will not come intp general use, but will rather remain only as a final resort. It is still in the experimental stage. The same applies to the use of sources of gamma-irradiation, as introduced and observed by Campbell.
I have not discussed interruption of the spinothalamic tracts in the brain, i. e. dorsal chordotomy (section of the external two-thirds of the ipsilateral posterior bundle (or section of Lissauer’s tract). These three operations are still in the experimental stage, and it would appear that they will not be generally introduced.