Operative management of patients with radiosurgery-related trigeminal neuralgia: analysis of the surgical morbidity and pain outcome.

OBJECT: Trigeminal neuralgia (TGN) occurring after radiosurgical treatment of cerebellopontine or petroclival tumors may be very difficult to control. Our aim was to determine the efficacy of neurosurgical treatment in regards to pain control and to evaluate the procedure-related complication and morbidity rates. METHODS: Retrospective study of a series of operated patients with radiosurgery-induced TGN. The primary goal of the surgery was to inspect and decompress the trigeminal nerve; the second goal was to remove the tumor remnant completely, if safely feasible. The main outcome measures were pain control, time to onset of pain relief and its duration, occurrence of new neurological deficits or worsening of the existing one and completeness of tumor removal. RESULTS: The four patients met the inclusion criteria: 2 with vestibular schwannomas, 1 with petroclival meningioma and 1 with an epidermoid. TGN occurred 12-60 months after radiosurgery (mean 39 months). At presentation the pain attacks occurred multiple timesdaily and lasted from a few seconds to 2-3min. The Complete tumor removal via the retrosigmoid approach was achieved in all cases. There were no major operative complications or persistent morbidity, besides one patient with trochlear nerve palsy. All patients experienced immediate pain relief after surgery. At follow-up (median duration - 42.5 months) the three patients reported complete pain resolution. One patient had occasional slight pain but did not need any medications. CONCLUSION: Surgery is safe and effective treatment option of patients with intractable radiosurgery-induced TGN. It leads to excellent pain control and is curative in regards to the neoplastic disease.

Anatomical study of endoscope-assisted far lateral keyhole approach to the ventral craniocervical region with neuronavigational guidance / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Image-guided neurosurgery, endoscopic-assisted neurosurgery and the keyhole approach are three important parts of minimally invasive neurosurgery and have played a significant role in treating skull base lesions. This study aimed to investigate the potential usefulness of coupling of the endoscope with the far lateral keyhole approach and image guidance at the ventral craniocervical junction in a cadaver model.</p><p><b>METHODS</b>We simulated far lateral keyhole approach bilaterally in five cadaveric head specimens (10 cranial hemispheres). Computed tomography-based image guidance was used for intraoperative navigation and for quantitative measurements. Skull base structures were observed using both an operating microscope and a rigid endoscope. The jugular tubercle and one-third of the occipital condyle were then drilled, and all specimens were observed under the microscope again. We measured and compared the exposure of the petroclivus area provided by the endoscope and by the operating microscope. Statistical analysis was performed by analysis of variance followed by the Student-Newman-Keuls test.</p><p><b>RESULTS</b>With endoscope assistance and image guidance, it was possible to observe the deep ventral craniocervical junction structures through three nerve gaps (among facial-acoustical nerves and the lower cranial nerves) and structures normally obstructed by the jugular tubercle and occipital condyle in the far lateral keyhole approach. The surgical area exposed in the petroclival region was significantly improved using the 0° endoscope (1147.80 mm(2)) compared with the operating microscope ((756.28 ± 50.73) mm(2)). The far lateral retrocondylar keyhole approach, using both 0° and 30° endoscopes, provided an exposure area ((1147.80 ± 159.57) mm(2) and (1409.94 ± 155.18) mm(2), respectively) greater than that of the far lateral transcondylar transtubercular keyhole approach ((1066.26 ± 165.06) mm(2)) (P < 0.05).</p><p><b>CONCLUSIONS</b>With the aid of the endoscope and image guidance, it is possible to approach the ventral craniocervical junction with the far lateral keyhole approach. The use of an angled-lens endoscope can significantly improve the exposure of the petroclival region without drilling the jugular tubercle and occipital condyle.</p>

Removal of vestibular schwannoma and facial nerve preservation using small suboccipital retrosigmoid craniotomy / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Vestibular schwannoma, the commonest form of intracranial schwannoma, arises from the Schwann cells investing the vestibular nerve. At present, the surgery for vestibular schwannoma remains one of the most complicated operations demanding for surgical skills in neurosurgery. And the trend of minimal invasion should also be the major influence on the management of patients with vestibular schwannomas. We summarized the microsurgical removal experience in a recent series of vestibular schwannomas and presented the operative technique and cranial nerve preservation in order to improve the rates of total tumor removal and facial nerve preservation.</p><p><b>METHODS</b>A retrospective analysis was performed in 145 patients over a 7-year period who suffered from vestibular schwannomas that had been microsurgically removed by suboccipital retrosigmoid transmeatus approach with small craniotomy. CT thinner scans revealed the tumor size in the internal auditory meatus and the relationship of the posterior wall of the internal acoustic meatus to the bone labyrinths preoperatively. Brain stem evoked potential was monitored intraoperatively. The posterior wall of the internal acoustic meatus was designedly drilled off. Patient records and operative reports, including data from the electrophysiological monitoring, follow-up audiometric examinations, and neuroradiological findings were analyzed.</p><p><b>RESULTS</b>Total tumor resection was achieved in 140 cases (96.6%) and subtotal resection in 5 cases. The anatomical integrity of the facial nerve was preserved in 91.0% (132/145) of the cases. Intracranial end-to-end anastomosis of the facial nerve was performed in 7 cases. Functional preservation of the facial nerve was achieved in 115 patients (Grade I and Grade II, 79.3%). No patient died in this series. Preservation of nerves and vessels were as important as tumor removal during the operation. CT thinner scan could show the relationship between the posterior wall of the internal acoustic meatus and bone labyrinths, that is helpful for a safe drilling of the posterior wall of the internal acoustic meatus.</p><p><b>CONCLUSIONS</b>The goal of every surgery should be the preservation of function of all cranial nerves. Using the retrosigmoid approach with small craniotomy is possible even for large schwannomas. Knowing the microanatomy of the cerebellopontine angle and internal auditory meatus, intraoperating neurophysiological monitoring of the facial nerve function, and the microsurgical techniques of the surgeons are all important factors for improving total tumor removal and preserving facial nerve function.</p>

Cystic trochlear nerve schwannoma. Case report.

BACKGROUND: Twenty-six cases of pathologically verified schwannomas of the trochlear nerve have been reported in the literature. Five of them had a large cystic component and a smaller solid portion. Complex skull base approaches have been usually applied for their removal. CASE DESCRIPTION: We report on a rare case of cystic trochlear schwannoma in a 52-year-old female patient. The patient presented with double vision, facial palsy, decreased hearing, hemiparesis on the right side, and severe gait instability. Magnetic resonance imaging revealed a 2.5-cm left-sided extra-axial lesion compressing the brain stem at the lower midbrain and upper pontine level. Total resection was performed via a retrosigmoid craniotomy. After the surgery, the neurological deficit diminished considerably. At 28 months follow-up, her only complaint was mild double vision when walking down the stairs and hypesthesia in the right half of her face. CONCLUSIONS: This case represents a rare pontomesencephalic lesion removed successfully via the simple retrosigmoid route.