Modified Skin Incision and Location of Burr-Hole Surgery via a Retrosigmoid Approach: An Anatomical Study

Objective This study aims to reduce the tissue damage during craniotomy with retrosigmoid approach. A modified sickle-shaped skin incision was developed, and a new burr-hole positioning method was proposed. Methods Five adult cadaveric heads (10 sides) were used in this study. The sickle-shaped skin incision was performed during craniotomy. The nerves, blood vessels, and muscles were observed and measured under a microscope. Additionally, 62 dry adult skull specimens (left sided, n = 35; right sided, n = 27) were used to measure the distance between the most commonly used locating point (asterion [Ast] point) and the posteroinferior point of the transverse sigmoid sinus junction (PSTS) (Ast-PSTS), as well as the distance between the new locating O point and the PSTS (O-PSTS). Then, the reliability of the new locating O point was validated on the same five adult cadaveric heads (10 sides) used for the sickle-shaped skin incision. Results The sickle-shaped skin incision reduced the damage to the occipital nerves, blood vessels, and muscles during the surgery via a retrosigmoid approach. The dispersion and variability of O-PSTS were smaller than those of Ast-PSTS. Conclusion The sickle-shaped skin incision of the retrosigmoid approach can reduce the tissue damage and can completely expose the structures in the cerebellopontine angle. The modified O point is a more reliable locating point for a burr-hole surgery than the Ast point.

Acoustic Neurinoma with Synchronous Ipsilateral Cerebellopontine Angle Lipoma: A Case Report and Review of the Literature

Lipomas of the cerebellopontine angle (CPA) and internal auditory canal (IAC) are relatively rare tumors. Acoustic neurinoma is the most common tumor in this location, which often causes hearing loss, vertigo, and tinnitus. Occasionally, this tumor compresses the brainstem, prompting surgical resection. Lipomas in this area may cause symptoms similar to neurinoma. However, they are not considered for surgical treatment because their removal may result in several additional deficits. Conservative therapy and repeated magnetic resonance imaging examinations for CPA/IAC lipomas are standard measures for preserving cranial nerve function. Herein, we report a case of acoustic neurinoma and CPA lipoma occurring in close proximity to each other ipsilaterally. The main symptom was hearing loss without facial nerve paralysis. Therefore, facial nerve injury had to be avoided. Considering the anatomical relationships among the tumors, cranial nerves, and CPA/IAC lipoma, we performed total surgical removal of the acoustic neurinoma. We intentionally left the lipoma untreated, which enabled facial nerve preservation. This report may be a useful reference for the differential diagnosis of similar cases in the future.

Transtentorial spread of glioblastoma multiforme to cerebellopontine angle – A rare case report

Background: Glioblastoma multiforme (GBM) is the most common central nervous system malignant tumor in adults with 48.3% of cases. Despite it, the presence of transtentorial spread is uncommon, with few patients reported in the literature. In this study, the authors report a case of GBM transtentorial spread to cerebellopontine angle after resection and adjuvant treatment. Case Description: A 55-year-old male patient with GBM, previously submitted to surgical resection and adjuvant treatment with radiotherapy and quemotherapy. Fourteen months after the first surgery, he developed headaches associated with dysphagia and dysphonia. Magnetic resonance imaging showed a recurrence of the left parietal lesion and a new mass in the right cerebellopontine angle. The patient underwent successful surgical resection of both lesions. Chemotherapy was maintained after the surgery. Conclusion: To the best of our knowledge, there are few cases of GBM metastasis to the cerebellopontine angle reported in the literature. Surgical management should be considered in cases of intracranial hypertension and patients with good performance status.

Diagnosis and Management of Vestibular Schwannoma: Focus on Dizziness

Vestibular schwannoma (VS) is commonly encountered in the cerebellopontine angle and benign neoplasms that arise from Schwann cells of the eighth cranial nerve, which can show not only hearing loss but also various vestibular symptoms. Dizziness is the symptom causing significantly negative effect on quality of life in patients with VS. Here, we will review the dizziness in VS.