The transcallosal approach for lesions affecting the lateral and third ventricles

Abstract

The study was carried out on a series of 42 patients who underwent surgery through a midline approach. Lesions were in the anterior part of the third ventricle in 32 cases, in the frontal horns in 6, in the trigone in 3, and in both lateral and third ventricles in 1 case. The third ventricle was approached through Monro's foramen in 22 cases and through an interfornicial route in 9 cases. Surgical mortality occurred in 2 cases (5%). Permanent morbidity occurred in another 2 cases (5%): it consisted of slight intellectual deterioration in one case and slight fixed pyramidal signs in the other. Transient mutism was the most frequently observed postoperative complication. Thirty-one patients were reviewed and submitted to neuropsychological tests in the late postoperative period to investigate the presence of intellectual deterioration or disturbances in the interhemispheric transfer of motor, somataesthetic and visual information. All patients showed only the presence of short-term memory disturbance. Furthermore, 12 patients tested before surgery also showed the presence of short-term memory deficits in the preoperative period. We conclude that a midline approach is the most direct and safe route to the third ventricle as well as to the frontal horns and trigone.

Comparative anatomical analysis of the transcallosal-transchoroidal and transcallosal-transforniceal-transchoroidal approaches to the third ventricle

“…29,32 There is evidence that a longitudinal callosotomy of up to 2 cm in the proximal region of the corpus callosum trunk does not cause significant neuropsychological changes, making the anterior transcallosal route a safe alternative for accessing ventricular lesions. 2,22,38,42 In the present study, we found a mean corpus callosum trunk thickness of approximately 10 mm, which was similar to that found in other studies. 19,31 Morphometric studies of individuals without neurological disease can most likely establish normal values of the corpus callosum subregions in a population to identify the presence and progression of a particular disease and to assist in the surgical planning of intraventricular lesions and some types of epilepsy.…”

“…The mean value of the working area of the transcallosal-transchoroidal approach was 121 mm 2 and that of the transcallosal-transforniceal-transchoroidal approach was 150 mm 2 . We therefore observed a mean increase of 29 mm 2 (p < 0.05) in working area after sectioning the fornix column ( Fig.…”

“…2,40 However, in certain situations, such as in the presence of severe hydrocephalus with reduced thickness of the frontal lobe parenchyma or in cases of cerebral atrophy with a thickness less than 30 mm, the transcorti- …”

“…30,38 There is evidence that a unilateral lesion of the fornix column has little or no impact on memory. 2,4,8,15,22,25,28,30,43 Various regions and structures participate in the memory circuit, and the fornix is just one of these structures. Changes to other parts of this circuit would therefore be necessary to establish a permanent memory deficit.…”

Neurocytoma Manifesting as Intraventricular Hemorrhage-Case Report-

“…1) The transcallosal approach is suitable for small lesions or lesions attached to the surface of the thalamus, due to the low risk of fornical injury during tumor removal and the small callosal section, which may not cause any new damage to the higher cortical functions such as disconnection syndrome. 1,3,10) The risk of memory disturbance is similar for the two approaches, and permanent memory disturbance is considered to be attributable to preoperative cognitive dysfunction. 1) The transcortical approach carries the risk of postoperative seizure and subcortical fiber injury in the dominant frontal lobe.…”