Abstract
Introduction:
Lesions in the thalamomesencephalic junction (TMJ) can be reached via an anterolateral approach, interhemispheric transventricular approach, transcortical (parieto-occipital lobule) approach, or trans-sylvian-insular approach. We now describe a new approach, a trans-sylvian–perforator approach (TPA), to this territory.
Methods:
A 33-year-old man with progressive right arm tremors, mild hemiparesis, and a cavernous malformation (CM) of the TMJ was followed for 5 years. Due to clinical progression he underwent a left orbitozygomatic approach to the CM, which could not be accessed due to a high-riding basilar artery. Hence, a new trans-sylvian corridor of exposure was developed using frameless neuronavigation. The trajectory was dorsal to M1 and led through the perforating branches of M1. Care was taken to avoid violating any arterial perforators. To reach the lesion, a small opening into the brain was created near the optic tract.
Results:
The CM was resected totally. Postoperatively, the patient's tremors were cured. No visual deficits were encountered. Imaging showed a small ischemic stroke in the basal ganglia likely related to manipulation of a perforator. Initially, his hemiparesis worsened, but it had improved almost completely within 6 months with residual moderate decrease in hand dexterity.
Conclusion:
The TPA effectively allowed access to the TMJ and was associated with acceptable morbidity. However, the safety of the approach needs further validation. Neuronavigation is indicated to choose the most direct trajectory through the M1 perforators. Tractography may help protect the optic tract.