Growth potential of small residual tumors after vestibular schwannoma surgery: comparison between remnants and the natural history of small tumors.

OBJECTIVE: Due to the heterogeneous definitions of tumor regrowth and various tumor volume distributions, the nature of small remnants after vestibular schwannoma (VS) surgery and the appropriate timing of adjuvant stereotactic radiosurgery for these remnants remain unclear. In this study, the growth potential of small remnants (< 1 cm3) after VS surgery was compared with that of treatment-naïve (TN) small VSs. METHODS: This retrospective single-center study included 44 patients with VS remnants following subtotal resection (STR) of a large VS (remnant group) and 75 patients with TN VS (< 1 cm3; TN group). A 20% change in tumor volume over the imaging interval indicated radiographic progression or regression. Tumor progression-free survival (TPFS) rates were estimated using the Kaplan-Meier method. RESULTS: In the remnant group, the mean preoperative tumor volume was 13.8 ± 9.0 cm3 and the mean tumor resection rate was 95% ± 5%. The mean tumor volume at the start of the observation period did not differ significantly between the two groups (remnant vs TN: 0.41 ± 0.29 vs 0.34 ± 0.28 cm3, p = 0.171). The median periods until tumor progression was detected were 15.1 (range 4.9-76.2) months and 44.7 (range 12.6-93.2) months in the TN and remnant groups, respectively. In the remnant group, the TPFS rates were 74% and 70% at 3 and 5 years after the surgery, respectively, compared with 59% and 47% in the TN group. The log-rank test demonstrated a significant difference (p = 0.008) in the TPFS rates between the two groups. Furthermore, 42 patients each from the remnant and TN groups were matched based on tumor volume. TPFS was significantly longer in the remnant group than in the TN group (3-year rates, 77% vs 62%; 5-year rates, 73% vs 51%; p = 0.02). In the remnant group, 18% of the tumor remnants demonstrated regression during follow-up, compared with 9% in the TN group, but this intergroup difference was not significant (p = 0.25). CONCLUSIONS: This study demonstrated that the growth potential of small VS remnants was lower than that of TN tumors. Observing for small remnants may be appropriate after STR of a large VS. Given the risk of tumor regrowth, careful observation using MRI should be mandatory during follow-up.

Arachnoid cyst alone causes hemifacial spasm: illustrative case.

BACKGROUND: Hemifacial spasm (HFS) due to an arachnoid cyst at the cerebellopontine angle is rare. Here, the authors reported such a case and analyzed the mechanism of facial nerve hyperactivity by reviewing the literature. OBSERVATIONS: A 40-year-old man presented with right HFS for the past 3 years. Preoperative magnetic resonance imaging revealed a right cerebellopontine angle cystic mass with high intensity on T2-weighted images, low intensity on T1-weighted and diffusion-weighted images, and no contrast effects. Cyst excision and decompression of the facial nerve using a lateral suboccipital approach to monitor abnormal muscle response (AMR) resulted in permanent relief. The cyst was histologically compatible with an arachnoid cyst. LESSONS: In the present case, when the cyst was dissected, the AMR disappeared and no offending arteries were detected around the root exit zone. Therefore, the cyst itself was responsible for HFS, for which AMR was useful. Limited cases of HFS due to arachnoid cysts without neurovascular compression have been previously reported. The authors suggested that pulsatile compression by the cyst results in facial nerve hyperactivity and secondary HFS.

An aberrant venous channel mimicking the perilabyrinthine cells in the petrous bone of a patient with vestibular schwannoma: illustrative case.

BACKGROUND: Anatomical variations, such as high jugular bulbs and air cell development in the petrosal bone, should be evaluated before surgery. Most bone defects in the internal auditory canal (IAC) posterior wall are observed in the perilabyrinthine cells. An aberrant vascular structure passing through the petrous bone is rare. OBSERVATIONS: A 48-year-old man presented with a right ear hearing disturbance. Magnetic resonance imaging revealed a 23-mm contrast-enhancing mass in the right cerebellopontine angle extending into the IAC, consistent with a right vestibular schwannoma. Preoperative bone window computed tomographic scans showed bone defects in the IAC posterior wall, which ran farther posteroinferiorly in the petrous bone, reaching the medial part of the jugular bulb. The tumor was accessed via a lateral suboccipital approach. There was no other major vein in the cerebellomedullary cistern, except for the vein running from the brain stem to the IAC posterior wall. To avoid complications due to venous congestion, the authors did not drill out the IAC posterior wall or remove the tumor in the IAC. LESSONS: Several aberrant veins in the petrous bone are primitive head sinus remnants. Although rare, their surgical implication is critical in patients with vestibular schwannomas.

Sagittal splitting of the temporalis muscle for encephalo-myo-synangiosis to prevent ischemic complications due to a swollen temporalis muscle without inhibiting collateral developments in patients with moyamoya disease.

OBJECTIVEEncephalo-myo-synangiosis (EMS) is an effective revascularization procedure for the treatment of moyamoya disease (MMD). However, the temporalis muscle used for EMS sometimes swells and causes ischemic complications by compressing the underlying brain. This study aimed to elucidate the effect of sagittal splitting (SS) of the muscle for prevention of ischemic complications and its impact on the postoperative development of collateral vessels.METHODSIn this historical case-control study, we analyzed 60 hemispheres in adult patients with MMD who underwent EMS using the temporalis muscle from December 1998 to November 2017. The muscle was divided anteroposteriorly by coronal splitting, and the anterior, posterior, or both parts of the muscle were used for EMS in 17, 4, and 39 hemispheres, respectively. In cases performed after 2006, the muscle was halved by SS, and the medial half was used for EMS to reduce the muscle volume (n = 47). The degree of postoperative muscle swelling was evaluated by measuring the maximum thickness of the muscle on CT scans obtained 3 to 7 days after surgery. The collateral developments of the anterior deep temporal artery (aDTA), posterior deep temporal artery (pDTA), and middle temporal artery (MTA) were assessed using digital subtraction angiography and MR angiography performed 6 months or more after surgery.RESULTSSS significantly reduced the temporalis muscle thickness from 12.1 ± 5.0 mm to 7.1 ± 3.0 mm (p < 0.01). Neurological deterioration due to the swollen temporalis muscle developed in 4 of the 13 hemispheres without SS (cerebral infarction in 1, reversible neurological deficit in 2, and convulsion in 1) but in none with SS. There were no significant differences in the postoperative collateral developments of the aDTA, pDTA, and MTA between hemispheres with and without SS. The MTA more frequently developed in hemispheres with EMS in which the posterior part of the muscle was used (30/37) than those in which this part was not used (4/16) (p < 0.01).CONCLUSIONSSS of the temporalis muscle might prevent neurological deterioration caused by the swollen temporalis muscle by reducing its volume without inhibiting the development of the collateral vessels.

Postoperative Cerebral Ischemia Due to Hypotension in Moyamoya Patient with Autonomic Dysfunction.

BACKGROUND: Hypotension is a significant risk factor for the development of ischemic complication following revascularization surgery for moyamoya disease (MMD). However, it is currently unknown whether autonomic dysfunction also plays a role. CASE DESCRIPTION: Here we report a case of MMD in which hypotension due to autonomic dysfunction caused postoperative cerebral ischemia. A 30-year-old female patient with MMD had a history of transient right hemiparesis following laughter. Single-photon emission computed tomography showed impaired cerebral blood flow (CBF) in both cerebral hemispheres, so she underwent revascularization surgery in her left cerebral hemisphere. She awoke from anesthesia uneventfully; however, 1 hour after the surgery her blood pressure suddenly dropped to 90/40 mm Hg and she became comatose. A perfusion computed tomography scan demonstrated a widespread reduction in CBF in the left hemisphere. Bezold-Jarisch reflex was thought to be the cause of the hypotension. Following treatment with a vasopressor agent, her BP increased and her consciousness rapidly recovered. The reduced CBF had almost completely recovered the next day. Head-up tilt test conducted 2 weeks after surgery demonstrated latent vasopressor-type autonomic dysfunction, which was possibly another cause of the hypotension. She was discharged from the hospital, and the laughter-induced hemiparesis gradually resolved. CONCLUSION: Situational neurologic deterioration in patients with MMD suggests latent autonomic dysfunction, which may be a risk factor for postoperative ischemic complications.

Cortical Venous Redness Represents Tissue Circulation Status in Patients With Moyamoya Disease.

BACKGROUND AND PURPOSE: Venous oxygen saturation (SO2) is measured in medical fields to assess tissue circulation insufficiency. This study aimed to elucidate the use of a cortical venous redness measurement to evaluate hemodynamic changes during revascularization surgery for patients with moyamoya disease. METHODS: In this retrospective case-series analysis, we first quantitatively measured and correlated SO2 and R intensity of 24-bit color digital red-green-blue pictures of blood samples from 3 volunteers. Subsequently, based on intraoperative digital pictures of 29 patients with moyamoya disease, we measured the R intensities of a cortical vein near the anastomosis site before and after anastomosis. Cerebral blood flow (CBF) at the site was measured using a single-photon emission computed tomography before and 1 to 3 days after surgery. Venous R intensity and CBF were measured twice by 4 raters, and their correlations were examined using generalized linear mixed effect model and linear regression analysis. RESULTS: A strong linear correlation was found between blood R intensity and its SO2 (coefficients, 0.522; 95% confidence interval, 0.364-0.680, using generalized linear mixed effect model). Venous R intensity before the anastomosis was not correlated with preoperative CBF (coefficients, 0.000352; 95% confidence interval, -0.000369 to 0.00107, by generalized linear mixed effect); however, the increases in venous R intensity after anastomosis were correlated with postoperative increases in CBF (R2, 0.367; 95% confidence interval, 0.116-0.618 to 0.548; 95% confidence interval, 0.331-0.764, by linear regression analysis). CONCLUSIONS: Cortical venous redness represented impaired CBF and could be a useful parameter for assessing hemodynamic changes during revascularization surgery.

[Diagnosis of Cochleovestibular Neurovascular Compression Syndrome:A Scoring System Based on Five Clinical Characteristics].

The optimal method for diagnosing cochleovestibular neurovascular compression syndrome(CNVC)remains controversial, and the aim of this study is to develop a standard diagnostic instrument for the condition. The clinical features of 53 sides of 50 patients with a combination of vertigo, tinnitus, and/or hearing loss were retrospectively evaluated. The following five clinical features were evaluated and given a score of 1 or 0:1)a long history of recurrent vertigo, tinnitus, or hearing loss;2)neurological findings related to positional vertigo, nystagmus, tinnitus, or hearing loss;3)neuro-otological findings involving tinnitus, audiometry, or vestibular testing;4)auditory brainstem response(ABR)evaluation with the detection of a low 25-75% II wave amplitude on the contralateral side and delayed interpeak latency in the I-III or I-V waves(usually low II wave amplitude combined with double peaks and a wide-based form)during ABR evaluation using 80 and 90dB clicks;and 5)the detection of vascular contact with the eighth cranial nerve on magnetic resonance imaging-constructive interference in steady state or air computed tomography imaging. Finally, the sum of these scores was evaluated. For cases in which more than one of the features of the items 1), 2), or 3) were present, the score was evaluated based on the most representative of the items. RESULTS: The patients were divided into those with scores of 4-5 and those with scores of 2-3. All the patients with scores of 4-5 exhibited CNVC, while those with scores of 2-3 had other diseases. Therefore, CNVC should be suspected in patients with scores of 4-5, but can be ruled out in those with scores of 2-3.

Subcortical Low-Intensity Lesions on Fluid-Attenuated Inversion Recovery Images After Revascularization Surgery for Moyamoya Disease.

OBJECTIVE: Although uncommon, subcortical low-intensity (SCLI) changes on fluid-attenuated inversion recovery images are observed in various diseases, including cerebral ischemia. Here, we aimed to clarify the incidence and clinical implications of SCLI changes after revascularization surgery for moyamoya disease, focusing on the correlation with postoperative transient neurologic events (TNEs). METHODS: In this retrospective case series analysis, we included 10 hemispheres from 9 adults with moyamoya disease who underwent revascularization surgery. Subcortical signal intensity at the 5 gyri around the anastomosis point was quantitatively measured at 1 week and 3 months postoperatively. Changes in cerebral blood flow (CBF) were assessed using single-photon emission computed tomography. RESULTS: Images taken 1 week after surgery showed widespread SCLI changes below the operative fields in all 10 cases, but these changes normalized by 3 months. In addition, the changes in signal intensity at anastomoses negatively correlated with the changes in CBF (R2 = 0.36; P = 0.039). Postoperative TNEs occurred in 6 cases (60%) but were resolved within 17 days after surgery. Postoperative CBF increased in 9 of the 10 cases, with a median of 23%; however, these increases were not associated with the development of TNEs. The SCLI changes at the anastomosis points did not differ by the experience of TNEs. CONCLUSIONS: Early after surgery, SCLI changes are common findings below the operative fields but negatively correlate with increases in CBF. Although no significant association was found between TNEs and the SCLI changes, the synchronized development of these phenomena may suggest a common underlying pathogenesis.

Metastatic cerebellar tumor of papillary thyroid carcinoma mimicking cerebellar hemangioblastoma.

INTRODUCTION: Well-differentiated papillary thyroid carcinoma generally (PTC) have a favorable prognosis. This metastasis is rare in the central nervous system. Brain metastasis has a relatively poor prognosis. We present a rare case of cerebellar metastasis, one that mimics a solid type cerebellar hemangioblastoma and because of which it was very hard to reach accurate preoperative diagnosis. Accurate diagnosis was challenging because of the similar imaging and histopathological findings for these two tumors. CASE DESCRIPTION: A brain lesion was detected by routine medical checkup of the brain with MRI in a 49-year-old woman 2 years after thyroidectomy for well-differentiated PTC. Gadolinium-enhanced MRI showed a homogeneous prominently enhanced lesion with surrounding enhanced dilated vessels in the left cerebellar hemisphere. Digital subtraction angiography showed a strongly stained lesion fed by the peripheral branch of the left posterior inferior cerebellar artery with drainage into the inferior vermian vein, revealing arteriovenous shunting. The most like likely preoperative diagnosis was felt to be that of a solid cerebellar hemangioblastoma. Gross total resection of the tumor was achieved by bilateral suboccipital craniotomy, and intraoperative pathological analysis suggested hemangioblastoma. Histopathological findings showed proliferation of vacuolated sheeted tumor cells with clear and eosinophilic cytoplasm and numerous thin-walled microvessels, consistent with hemangioblastoma. However, the final diagnosis was brain metastasis of the follicular variant of PTC due to a partial thyroid follicle-like pattern including eosinophilic fluid pathologically and positive TTF-1 immunostaining. DISCUSSION AND EVALUATION: Since presented rare case of cerebellar metastasis of PTC was very similar to solid type cerebellar hemangioblastoma on imaging and histopathological findings, accurate diagnosis was challenging. Moreover, it is extremely rare for a cerebellar metastasis to occur as an initial distant metastasis of PTC, and hemangioblastoma is the most common primary cerebellar neoplasm in adults. This epidemiological data was also one of the reason of difficulty to reach preoperative accurate diagnosis. CONCLUSIONS: To the best of our knowledge, there are no other reports of challenging diagnosis case of these two tumors in the literature. Brain metastasis of a well-differentiated PTC could be a relatively poor prognostic factor, and accurate diagnosis and suitable surgical therapy or radiotherapy are needed.

[Abducens palsy due to unruptured aneurysms of the internal carotid artery in a patient with systemic lupus erythematosus].

We report a rare case of unruptured aneurysms in systemic lupus erythematosus (SLE). A 28-year-old female who had suffered from SLE for 5 years was admitted to our hospital because she noticed diplopia three weeks before. She presented with left abducens palsy on admission. CT scans revealed intracranial multiple calcified lesions. MRA and the cerebral angiography showed multiple saccular aneurysms from the cavernous segment to the petrous segment of the left internal carotid artery (ICA). These findings suggested that left abducens palsy was related to cranial nerve compression due to the aneurysm at the cavernous segment of the left ICA. As balloon occlusion test for 15 minutes of the left ICA with 99mTc-HMPAO SPECT was tolerable, the patient underwent the endovascular trapping of multiple aneurysms from the cavernous segment to the petrous segment of the left ICA with detachable coils. Postoperative course was uneventful and left abducens palsy fully recovered. She was discharged with no neurological deficits. This is the first report presenting left abducens palsy due to unruptured aneurysms in SLE. We summarized the previous reports of cerebral aneurysms in SLE.

[Leptomeningeal carcinomatosis following 27 years remission from breast cancer with epidermoid: a case report].

We herein report a patient with leptomeningeal carcinomatosis (LC) in long-term remission from breast cancer, co-existing with a posterior fossa epidermoid and an increase in the serum CA19-9 level which complicated the diagnosis. A 59-year-old woman underwent a left mastectomy due to breast cancer 27 years ago. She was admitted to our hospital suffering from a headache and diplopia. Her serum CA19-9 level on admission was elevated, and diffusion weighted images showed a high-intensity tumor in the prepontine and left cerebello-pontine cistern. A left lateral suboccipital craniotomy with endoscopic assistance was performed for tissue sampling. The pathological diagnosis was an epidermoid and LC from breast cancer. She died of progression of leptomeningeal carcinomatosis 31 days after surgery. LC alone following long-term remission from breast cancer is extremely rare. Meningeal irritation co-existing with an epidermoid mimicking chemical meningitis is even rarer. Pathological confirmation is required for such rare cases.

[Superficial temporal artery-middle cerebral artery anastomosis in a patient of temporal arteritis with internal carotid artery occlusion: a case report].

Temporal arteritis is a rare systemic autoimmune disease and the arteritic process in this case of temporal arteritis involved large and medium-size arteries. Temporal arteritis with internal carotid artery (ICA) occlusion is very rare. We report a case of temporal arteritis with ICA occlusion following superficial temporal artery (STA) -middle cerebral artery (MCA) anastomosis, together with steroid therapy. A 73-year-old female presented with a headache, visual disturbance of left side, and suppression of activity. Left STA was inflammatory and overswelling. Magnetic resonance angiography (MRA) and angiography revealed occlusion of the left internal carotid artery (ICA) at the cervical portion and lowering of vascular reserve on PAO SPECT. Diagnosis as temporal arteritis was conclusive due to the clinical presentation, laboratory studies, and left temporal artery biopsy, so steroid pulse therapy was initiated. Inflammation of left STA disappeared after steroid therapy, but left ICA occlusion on angiography and lowering of vascular reserve on SPECT remained for 3 months afterwards. Because of this, STA-MCA anastomosis was performed. There were no complications after the operation and the donor artery has been patent for two years. Temporal arteritis with ICA occlusion that requires extracranial-intracranial bypass (EC-IC bypass) is very rare. STA-MCA anastomosis with steroid therapy is effective for the prevention of cerebral infarction.

Cerebellopontine angle facial schwannoma relapsing towards middle cranial fossa.

Facial nerve schwannomas involving posterior and middle fossas are quite rare. Here, we report an unusual case of cerebellopontine angle facial schwannoma that involved the middle cranial fossa, two years after the first operation. A 53-year-old woman presented with a 3-year history of a progressive left side hearing loss and 6-month history of a left facial spasm and palsy. Magnetic resonance imaging (MRI) revealed 4.5 cm diameter of left cerebellopontine angle and small middle fossa tumor. The tumor was subtotally removed via a suboccipital retrosigmoid approach. The tumor relapsed towards middle cranial fossa within a two-year period. By subtemporal approach with zygomatic arch osteotomy, the tumor was subtotally removed except that in the petrous bone involving the facial nerve. In both surgical procedures, intraoperative monitoring identified the facial nerve, resulting in preserved facial function. The tumor in the present case arose from broad segment of facial nerve encompassing cerebellopontine angle, meatus, geniculate/labyrinthine and possibly great petrosal nerve, in view of variable symptoms. Preservation of anatomic continuity of the facial nerve should be attempted, and the staged operation via retrosigmoid and middle fossa approaches using intraoperative facial monitoring, may result in preservation of the facial nerve.

Occipital inter-hemispheric approach for lateral ventricular trigone meningioma.

OBJECTIVE: The optimal surgical approach for a trigone meningioma is still controversial. Here, we report two patients with trigone meningioma treated successfully via an occipital inter-hemispheric and trans-cortical approach in the lateral semi-prone position. CLINICAL PRESENTATION: A 53-year-old woman was admitted to a local hospital with sudden transient dizziness and vomiting. The CT brain scan demonstrated a right intra-ventricular tumour. She was therefore transferred to our hospital for surgical treatment. The other patient was a 67-year-old woman who was admitted to a local hospital after a traffic accident and a CT brain scan revealed an incidental right intra-ventricular tumour. After referral to our hospital, periodic MRI examinations revealed gradual tumour enlargement within a one-year period. Neither of the patients had any neurological deficits, including in the visual fields. INTERVENTION: The head of each patient was positioned so that the tumour-containing right ventricle was oriented downwards and laterally. An occipital inter-hemispheric approach was performed and using a navigation system, the tumour was identified about 1 cm in depth from the cortical surface. After the medial part of the tumour was debulked, the posterior and then the anterior choroidal blood supplies to the tumour were identified. Occlusion of these vessels achieved tumour haemostasis. The tumours were totally removed via a 1.5-cm cortical incision. Brain retraction was minimal because the right hemisphere was pulled down by gravity. Therefore, the para-splenial cisterns were easily accessed, resulting in early release of cerebrospinal fluid. Post-operative MRI showed complete removal of the tumour and the patients had no neurological deficits. Anti-epileptic medication was withdrawn one week after the operation. CONCLUSIONS: The occipital inter-hemispheric fissure lacks important bridging veins. The approach used and patient positioning minimized damage to the lateral aspect of the optic radiation and the corpus callosum. Except in patients with very large trigone meningiomas, this approach is useful for decreasing the risk of post-operative hemianopsia or epilepsy, and possibly speech disturbance, even in patients with a tumour in the dominant hemisphere.