Thalamic pilocytic astrocytoma
Diagnosis
El Ahmadieh et al. recommended that all of these tumors be evaluated for the H3K27M mutation. Further, they believe that H3 K27M-mutant thalamic pilocytic astrocytomas require aggressive multi-modality treatment and that these treatments should be guided by the molecular findings, as opposed to the histologic ones 1).
Approach
The choice of surgical approach during resection is dictated by the location of the displaced normal thalamus and posterior limb of the internal capsule (PLIC) or crus posterius. Diffusion tensor imaging and white matter tractography can identify the location of the PLIC in relation to the tumor and may be useful in planning the operative trajectory 2).
Videos
Surgical resection is the primary pilocytic astrocytoma treatment and total resection can be curative. However, these lesions occur in critical areas, such as the thalamus, being surrounded by critical life neurovascular structures, which imposes a surgical challenge.
Exhaustive acquisition and meticulous interpretation of preoperative radiological exams; reliable surgical orientation based on profound microneurosurgical anatomic knowledge and judicious discernment of the neuroanatomic distortions on the surface and deep-seated structures inflicted by the neuropathological entity; embracing and comprehensive application of the vast scope of available intraoperative guidance imaging and neurophysiological monitoring; in alliance with the mastered carefully microsurgical technique supported by endoscopic visualization are the keystones to the pursed duet “cure with quality of life” in the treatment of these lesions.
Kadri et al. from the Department of Neurosurgery, Federal University of Mato Grosso do Sul, Campo Grande, Brazil. and Brigham and Women's Hospital presented the case of a 17-yr-old young lady with a progressive motor deficit in her right hemibody for over 2 yr. Her radiological investigation demonstrated a left thalamic lesion displacing the projection fibers (corticospinal tract) within the internal capsule laterally. The patient consented to the surgical procedure. The surgical strategy, intraoperative findings, and microsurgical and endoscopic technique, as well as the postoperative radiological and clinical evaluation are presented 3).
Outcome
Gross total removal of thalamic pilocytic astrocytomas with low morbidity and mortality can be achieved by computer-assisted stereotactic volumetric resection techniques. Gross total resection of these lesions confers a favorable long-term prognosis without adjuvant chemotherapy and/or radiation therapy and leads to the improvement of neurological deficits 4)