PMC10008844_01
Preoperative radiographic findings. (A) FIESTA demonstrates an extra-axial lobulated mass at the left CPA, extending to the prepontine/interpeduncular cisterns as well as the ipsilateral FM, compressing the brainstem, and cranial nerves. There is also an extension into the ipsilateral IAC with encasement of the basilar artery. White arrow: tumor. (B) Axial DWI image shows bright signals in the CPA cistern. CPA, cerebellopontine angle; FM, foramen magnum; IAC, internal auditory canal.
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F1
Fast imaging employing steady-state acquisition (FIESTA) showed an extra-axial left CPA space-occupying lesion extending to the prepontine cistern, anterior to the basilar artery, superior to the chiasma, and caudally to the FM (Figure 1A). It has a lobulated outline with low T1-weighted imaging (T1WI), high T2WI, and heterogeneous fluid-attenuated inversion recovery (FLAIR) signals with evident diffusion restriction (Figure 1B).
Intraoperative findings of the ATP. Microsurgical maneuvers of the ATP are shown. (A) Skin incision and patient's position (Park bench) are shown. (B) Burr-hole placement for the one-piece temporal-suboccipital craniotomy is shown. (C) Surgical field of the ATP is shown (1). The MCF dura is elevated toward the petrous ridge. The middle meningeal artery is coagulated and divided. After the GSPN is preserved, the landmarks for drilling Kawase's quadrangle are identified (2). The tentorium is opened exposing the trigeminal nerve superior to petroclival tumor. Trochlear nerve is exposed coursing over tumor before entering tentorium (3). Trigeminal nerve is compressed by tumor (4). Tumor removal of the prepontine cistern and supratentorial region is done. BA, brainstem (5), and oculomotor nerve (6) are identified. The lower limit of this exposure is the abducens nerve (7). Trigeminal nerve decompression is done (8). ATP, anterior transpetrosal approach; MCF, middle cranial fossa; AE, arcuate eminence; BA, basilar artery; EAC, external auditory canal; GSPN, greater superficial petrosal nerve; KT, Kawase's triangle; T, tumor; TI, trigeminal impression; TS, transverse sinus; SS, sigmoid sinus.
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F2
The head was placed in the horizontal position, with the body in the lateral position (Figure 2A). The skin incision began 1 cm anterior to the tragus, went cranially until the superior temporal line, turned posteriorly, then turned caudally approximately 6 cm posterior to the external auditory canal, and ended around the FM (Figure 2A). Multiple burr holes were placed as described in Figure 2B. Microsurgical maneuvers of the ATP are shown in Figure 2C.
Intraoperative findings of the LSO. Microsurgical maneuvers of the LSO are shown. Surgical field of the LSO is shown. SS is skeletonized. Foramen magnum decompression is performed (1). The dura is incised in a C-shape fashion, and the cerebellar hemisphere is gently retracted to expose the cerebellomedullary cistern (2). Tumor removal around the trigeminal nerve (3), facial/vestibulocochlear nerves (4), and LCN (5) is done. Tumors growing below vertebral artery (VA) and hypoglossal nerve are removed (5). Tumor extending into the IAC is gently removed with curette (6). The decompression is achieved by removing bone posterior and inferior to the IAC. The one-piece temporal-suboccipital bone flap is replaced and attached to the surrounding bone with titanium plates and screws (7). IAC, internal auditory canal; FM, foramen magnum; IAA, internal auditory artery; JF, jugular foramen; LCN, lower cranial nerves; T, tumor; TS, transverse sinus; SS, sigmoid sinus.
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F3
Figure 3. FM decompression was performed to increase the volume of the PCF.
Postoperative radiographic findings. (A) Postoperative DWI shows near-total removal of epidermoid cyst in the supra/infra tentorial regions. A small amount of tumor remains around the optic chiasm. (B) Postoperative FIESTA shows that the decompression of trochlear nerve, trigeminal nerve, facial/vestibulocochlear nerves, LCN, and hypoglossal nerve is achieved. (C) Head CT bone window images show the one-piece temporal-suboccipital craniotomy (left panel: axial view, right panel: three-dimensional reconstruction). (D) Schematic diagram illustrating the difference between this approach and CTP. FIESTA, fast imaging employing steady-state acquisition; LCN, lower cranial nerves; CTP, combined transpetrosal approach; ATP, anterior transpetrosal approach; IAC, internal auditory canal; PTP, posterior transpetrosal approach; RA, retrosigmoid approach; SC, semicircular canal.
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F4
Postoperative Diffusion-weighted imaging (DWI) displayed near-total tumor removal (Figure 4A). FIESTA showed that the decompression of all cranial nerves is achieved in the PCF (Figure 4B). Craniotomy size is shown in Figure 4C.