Transsylvian Hemispheric Deafferentation

The transsylvian hemispheric deafferentation is a keyhole procedure to replace anatomic or functional hemispherectomies. Its advantages are the significant reduction in surgery time, blood loss, and postoperative rate of hydrocephalus. The indication, the imaging studies, and presurgical evaluation are similar to that of other hemispherotomy procedures. The key elements are a small sylvian craniotomy and transsylvian exposure of insular cortex followed by opening of ventricular system along a transcortical access through the circumference of the insula. The disconnection from the frontal horn through the basal frontal white matter and cortex is guided by the M1 and A1 structure. By following the A2, a paramesial callosal fiber transection is done following the inferior rim of the falx, and then the rim of the tentorium to the temporomesial disconnection. A total of 113 transsylvian keyhole procedures were done, including 71 paediatric keyhole procedures with good follow-up and detailed outcome data. International League for Epilepsy (ILAE) class I outcome was achieved in 89% of paediatric keyhole procedures.