Neuronavigation-guided endoscopic and hodotopic approach to an arachnoid cyst

BACKGROUND: Arachnoid cysts are intraarachnoid benign cystic lesions filled with cerebrospinal fluid and should be treated without incurring further morbidity to the patients. CASE DESCRIPTION: The authors present a case of a 68-year-old elderly female with a large right fronto-parieto-temporal arachnoid cyst who has been suffering from mild left hemiparesis for the past 4 years and presented with sudden onset of seizures. The 3 Tesla MR system with diffusion tensor imaging (DTI) and MR tractography of the brain showed a large right fronto-parieto-temporal cystic lesion measuring 7 × 5 × 5 cm with a midline shift of 1 cm, suggestive of an arachnoid cyst with surrounding ipsilateral white matter projection pathways and inferior occipito-frontal fasciculus or inferior longitudinal white matter tracts. The cyst was successfully treated with neuronavigation-guided endoscopic and hodotopical approach to fenestrate the arachnoid cyst into the sylvian cistern, avoiding inadvertent injury to major white matter tracts portrayed by DTI. Postoperatively, a repeated computed tomography (CT) scan of the brain revealed a smaller arachnoid cyst with correction of the midline shift. The patient was weaned off from the ventilator and her hemiplegia improved gradually. CONCLUSION: This case report emphasizes the value of neuronavigation-guided endoscopic and hodotopic approach to fenestrate the intra-axial arachnoid cyst.