Tract Identification by Novel MRI Signal Changes following Stereotactic Anterior Capsulotomy

Abstract

Background: Five patients underwent magnetic resonance imaging (MRI) following MRI-guided stereotactic bilateral anterior capsulotomy to detect lesion-related anatomic changes. Methods: Five disabled and treatment-resistant patients with major depression (n = 4) and obsessive-compulsive disorder (n = 1) underwent stereotactic bilateral anterior capsulotomy. All patients had postoperative MRI at 2 months and at 1–4 years after surgery. An additional patient who had a pure motor deficit following a spontaneous basal ganglia hemorrhagic stroke was imaged as a comparator. Results: The 2-month postcapsulotomy MRI showed a previously undescribed increase in T₁-weighted signal within similar neural pathways for each patient. These pathways showed no changes in T₂-weighted or fluid-attenuated inversion recovery sequences. The signal changes are different from the expected changes associated with anterograde Wallerian degeneration and identify retrograde changes in the proximal segment of the interrupted axon. Conclusion: Previously undescribed T₁-weighted signal alterations following stereotactic surgery identify retrograde non-Wallerian changes in interrupted axons and provide a new method in identifying and tracing lesioned pathways.

Poststroke Cerebral Peduncular Atrophy Correlates with a Measure of Corticospinal Tract Injury in the Cerebral Hemisphere

“…[5][6][7] In either case, the volume loss does not become visible until at least several months poststroke. [8][9][10][11][12][13] The cerebral peduncle is ideal for assessing postinfarction wallerian degeneration, because its fibers (which are corticofugal) are completely arrayed in parallel, in contrast to most other brain stem areas. 14,15 The degree of peduncular atrophy from wallerian degeneration after supratentorial infarction can be conveniently expressed by dividing the peduncular area on the atrophied side by the area on the contralateral side at the same level in the axial plane.…”

Long term outcome of thermal anterior capsulotomy for chronic, treatment refractory depression

“…Fibres within the anterior limb of the internal capsule constitute three distinct fibre tracts54: (1) fibres originating in the anterior thalamic peduncle, which connect to the cingulum bundle,55 the target of anterior cingulotomy; (2) a deeper system of fibres made up of frontopontine fibres; and (3) a third set which does not run in bundles and connects the caudate nucleus and the lentiform nucleus. A recent neuroimaging study demonstrated neuronal degeneration within these three pathways in five patients after ACAPS 56. A mechanism of action for ACAPS is, as yet, unknown.…”

Tractographic Analysis of Historical Lesion Surgery for Depression

“…It is noteworthy that lesions placed in the AC in the past have been located in the most inferior part of the ALIC (Hurwitz et al, 2006). In a postoperative effort to demonstrate degenerating brain regions with T1-weighted MRI after anterior capsulotomies, two affected neuronal systems in depressed patients were identified.…”