Microsurgery of Koos I-II vestibular schwannomas: a case series of 100 consecutive patients.

BACKGROUND: Treatment of small vestibular schwannomas (VS) depends on size, growth pattern, age, symptoms, co-morbidities. Watchful waiting, stereotactic radiosurgery and microsurgery are three valid options of treatment. METHODS: We reviewed clinical sheets, surgical data and results of 100 consecutive patients with Koos Grade I-II VS, operated at our department via a retrosigmoid microsurgical approach between September 2010 and July 2021. Extent of resection was assessed as total, near-total or subtotal. The course of facial nerve (FN) around the tumor was classified as anterior (A), anterior-inferior (AI), anterior-superior (AS) and dorsal (D). FN function was assessed according to House-Brackmann (HB) Scale and hearing level according to AAO-HNS Classification. RESULTS: Mean tumor size was 1.52 cm. FN course was mainly AS (46.0%) in the overall cohort; in Koos I VS, FN was AS in 83.3%. Postoperative FN function was HB I in 97% and HB II in 3% of cases. Hearing preservation (AAO-HNS class A-B) was possible in 63.2% of procedures. Total/near-total removal was achieved in 98%. Postoperative mortality was zero. Transient complications were observed in 8% of patients; permanent complications never occurred. Tumor remnant progression was observed in one case, 5 years after subtotal removal. CONCLUSIONS: Microsurgery represents a valid option for management of VS, including Koos I-II grades, with an acceptable complication rate. In particular, in small VS long-term FN facial outcome, HP and total/near-total removal rate are favorable.

Surgical management of spinal schwannomas arising from the first and second cervical roots: Results of a cumulative case series.

Objective: Schwannomas of the first and second nerve roots are rare neurosurgical entities, harboring specific surgical features that make surgical resection particularly challenging and deserve specifics dissertations. This study is a retrospectively analysis of 14 patients operated in two different neurosurgical centers: the San Filippo Neri Hospital of Rome and the Federal Centre of Neurosurgery of Tjumen. Materials and Methods: In the last 6 years, 14 patients underwent neurosurgical resection of high cervical (C1-C2) schwannomas, in two different neurosurgical centers. Patients data regarding clinical presentation, radiological findings, and surgical results were retrospectively analyzed. Results: The mean age was 50 years (range 13-74), the follow-up mean duration was 30 ± 8.5 (range 24-72 months), and there was no significant differences among different tumor locations (intradural, extradural, and dumbbell). Surgical results were excellent: gross total resection was achieved in all cases and there were no intraoperative complications or postoperative mortality. All patients presented postoperative clinical improvement except one who remained stable. Karnofsky performance status, at the last follow-up, confirmed a global clinical improvement. No vertebral artery (VA) injury neither spinal instability occurred; nerve root sacrifice was reported in one case. Conclusions: Neurosurgical treatment of C1-C2 schwannomas is associated with good outcomes in terms of extent of resection and neurological function. In particular, dumbbell shape and VA involvement do not represent limitations to achieve complete tumor resection and good clinical outcome. In conclusion, microsurgery represents the treatment of choice for C1-C2 schwannomas.

Preoperative vestibular evoked myogenic potentials (VEMPs), caloric test, and pure tone audiometry to identify the vestibular nerve branch of schwannoma origin: preliminary results in a series of 26 cases.

Vestibular schwannoma (VS) is a benign tumor which develops in the internal auditory canal and the cerebellopontine angle, potentially diminishing hearing or balance. Most VS tumors arise from one of two vestibular branches: the superior or inferior vestibular nerve. Determining the specific nerve of origin could improve patient management in terms of preoperative counseling, treatment selection, and surgical decision-making and planning. The aim of this study was to introduce a preoperative testing protocol with high accuracy to determine the nerve branch of origin. The nerve of origin was predicted on the basis of preoperative vestibular evoked myogenic potentials (VEMPs), caloric stimulation test, and pure tone audiometry on 26 recipients. The acquired data were entered into a statistic scoring system developed to allocate the tumor origin. Finally, the nerve of origin was definitively determined intraoperatively. Receiver operating characteristic (ROC) curves analysis of preoperative testing data showed the possibility of predicting the branch of origin. In particular, ROC curve of combined VEMPs absence, nystagmus detectable at caloric stimulation, and PTA < 75 dB HL allowed to obtain high accuracy for inferior vestibular nerve implant of the tumor (area under the curve-AUC = 0.8788, p = 0.012). In 24 of 26 cases, the preoperatively predicted tumor origin was the same as the origin determined during surgery. Preoperative audiological and vestibular evaluation can predict the vestibular tumor branch of origin with high accuracy. Despite the necessity of larger prospective cohort studies, these findings may change preoperative approach, possible functional aspects, and counseling with the patients.

Single-Level Cervical Arthroplasty with a Keel-less Prosthesis: Results in a Series of 35 Patients Operated on for Soft Disk Herniation with a Minimum of 3 Years of Follow-Up.

BACKGROUND: Cervical arthroplasty with artificial cervical disks has gained popularity as an alternative to anterior discectomy and fusion. The main advantages of disk arthroplasty include maintenance of the range of movement, restitution of disk height and spinal alignment, and reduction of adjacent segment degeneration (ASD). In this article, we aimed to assess the outcomes of the use of a keel-less prosthesis. MATERIAL AND METHODS: We included all the patients who underwent single-level cervical arthroplasties with the Discocerv Cervidisc Evolution for "soft" disk herniation. Clinical assessment included Neck Disability Index (NDI) and visual analog scale (VAS) for neck and arm pain. Radiologic studies investigated the occurrence of ASD and system failure or subsidence. The reoperation rate was also recorded. RESULTS: The study included 35 patients (14 men and 21 women; mean age: 42.5 years; mean follow-up: 57.8 months). There was a significant decrease in VAS neck and VAS arm scores, which went from 7.2 and 6.9 preoperatively to 2.2 and 1.7 postoperatively, 2.2 and 1.6 at 6 months, 2.0 and 1.8 at 1 year, and 2.1 and 1.3 at the last follow-up, respectively. The mean NDI score was 58.0 preoperatively, 19.4 postoperatively, 17.0 at 6 months, 16.1 at 1 year, and 16.2 at the last follow-up. Radiologic studies revealed a preserved range of motion in 33 of 35 patients. No ASD occurred and no reoperation was required. CONCLUSIONS: Cervical disk arthroplasty with a keel-less prosthesis can be a safe and effective alternative to fusion for degenerative disk disease in selected patients, with a possible reduction of ASD.

Koos grade IV vestibular schwannomas: considerations on a consecutive series of 60 cases-searching for the balance between preservation of function and maximal tumor removal.

Koos grade IV vestibular schwannomas (VS) (maximum diameter > 3 cm) compress the brainstem and displace the fourth ventricle. Microsurgical resection with attention to the right balance between preservation of function and maximal tumor removal is the treatment of choice. Our series consists of 60 consecutive patients with unilateral VS, operated on from December 2010 to July 2019. All patients underwent microsurgical removal via the retrosigmoid approach. The adherence of VS' capsule to the surrounding nervous structures and the excessive tendency of tumor to bleed during debulking, because of a redundant vascular architecture, was evaluated by reviewing video records. Microsurgical removal of tumor was classified as total (T), near-total (NT: residue < 5%), subtotal (ST: residue 5-10%), or partial (P: residue > 10%). Maximal mean tumor diameter was 3,97 cm (SD ± 1,13; range 3,1-5,8 cm). Preoperative severely impaired hearing or deafness (AAO-HNS classes C-D) was present in 52 cases (86,7%). Total or NT resection was accomplished in 46 cases (76,7%), 65,8% in cases with, and 95,4% without tight adhesion of capsule to nervous structures (p < 0,001). Endoscopic-assisted microsurgical removal of VS in the IAC was performed in 23 patients: in these cases, a T resection was obtained in 78,3% versus 45,9% of microsurgery only (p < 0,001). The capsule of VS was tightly adherent to nervous structures in 63,3% of patients, whereas hypervascular high-bleeding tumors represented 56,7%. Hearing preservation was possible in 2 out of 8 patients with preoperative class B hearing. At last follow-up, 34 (56,7%) patients had a normal postoperative FN outcome (HBI), 9 (15,0%) were HBII, 8 (13,3%) HBIII, and 9 (15,0%) HBIV. The total NT resection of solid and low-bleeding VS, without tight capsule adhesion, was associated with better FN outcome. Mortality was zero; permanent complications were observed in 2 cases (diplopia, hydrocephalus), transient in 9. Microsurgery of Koos grade IV VS seems to be associated with more than acceptable functional results, with high rate of T and NT removal of tumor. Long-term FN results seem to be worse in patients with cystic Koos grade IV VS, in cases with tight capsule adherences to nervous structures and in high-bleeding tumors.

Flexible endoscopic assistance in the surgical management of vestibular schwannomas.

Endoscopic-assisted techniques have extensively been applied to vestibular schwannoma (VS) surgery allowing to increase the extent of resection, minimize complications, and preserve facial nerve and auditory functions. In this paper, we retrospectively analyze the effectiveness of flexible endoscope in the endoscopic-assisted retrosigmoid approach for the surgical management of VS of various sizes. The authors conducted a retrospective analysis on 32 patients who underwent combined microscopic and flexible endoscopic resection of VS of various sizes over a period of 16 months. Flexible endoscopic-assisted retrosigmoid approach was performed in all cases, and in 6 cases, flexible and rigid endoscopic control were used in combination to evaluate the differences between the two surgical instruments. The surgical results were additionally compared with a previous case series of 141 patients operated for VS of various sizes without endoscopic assistance. Gross-total resection was achieved in 84% of the cases and near-total resection was accomplished in the rest of them. Excellent or good facial nerve function was observed in all except one case with a preoperative severe facial palsy. Hearing preservation surgery (HPS) was attempted in 11 cases and accomplished in 9 (81.8%). A tumor remnant was endoscopically identified in the fundus of the IAC in all cases (100%). Endoscopic assistance increased the rate of total removal and no intrameatal residual tumor was seen at radiological follow-up. Comparative analysis with a surgical cohort of patients operated with the sole microsurgical technique showed a significative association between endoscopic assistance and intracanalicular extent of resection. Combined microsurgical and flexible endoscopic assistance provides remarkable advantages in the pursuit of maximal safe resection of VS and preservation of facial nerve and auditory functions, minimizing the risk of post-operative complications.

Postoperative Functional Preservation of Facial Nerve in Cystic Vestibular Schwannoma.

OBJECTIVE: To retrospectively analyze clinical and surgical data of a consecutive series of 26 patients with unilateral cystic vestibular schwannomas. METHODS: Tumors were classified as type A (central cyst) and type B (peripheral cyst) and as small (tumor diameter <3 cm) and large (tumor diameter >3 cm). All patients underwent microsurgical removal via retrosigmoid approach. The course of the facial nerve (FN) was classified as anterior, anterior-inferior, anterior-superior, and dorsal to the tumor's surface. RESULTS: Mean patient age was 53.5 years. Mean tumor size was 3.2 cm. There were 22 cases classified as type A and only 4 as type B. Total or near-total resection (>95%) was achieved in 16 cases (61.5%), subtotal removal (90%-95%) was achieved in 9 cases (34.6%), and partial removal (<90%) was achieved in 1 case (3.9%). Position pattern of FN was anterior-inferior in 10 cases (38.4%), anterior-superior in 10 cases (38.4%), anterior in 23.2% of 6 cases. At hospital discharge, FN function was House-Brackmann grade I-V in 9 (36%), 10 (38%), 3 (12%), 3 (12%), and 1 (4%) patients; at final follow-up, House-Brackmann grades I, II, III, and IV accounted for 18 (72%), 6 (24%), 1, and 1 cases. During follow-up ranging from 6 months to 10 years, reoperation for growing of residue was never necessary. CONCLUSIONS: According to the literature and the results of our series, microneurosurgery of cystic vestibular schwannomas is associated with good outcomes in terms of extent of resection and FN function. In particular, long-term FN function is much more satisfactory than short-term function. In most cases, microsurgery represents the treatment of choice of cystic vestibular schwannomas.

Extended Middle Cranial Fossa Approach for Lesions Invading Infratemporal Fossa: Anatomic Study and Clinical Application.

Skull base tumors arising from the middle cranial fossa and invading of the infratemporal fossa (ITF) and middle cranial fossa are challenging for neurosurgeons, because of complex anatomy and critical neurovascular structure involvement. The first pioneering ITF approaches resulted in invasive procedures and carried a high rate of surgical morbidity. However, the acquisition of deep anatomical knowledge, and the development operative skills and reconstruction techniques allowed surgeons to achieve total or near total resection of many ITF lesions with a low morbidity rate. In Video 1 we illustrate our technique for the anterior ITF approach for the surgical treatment of a middle cranial fossa meningioma invading the ITF. This surgical video describes the anterior ITF approach in 2 steps. First, a standard extradural middle fossa approach subtemporal approach is performed on a cadaveric specimen, illustrating the anterior extension to the cavernous sinus. Second, the anterior ITF approach is performed for the surgical treatment of a temporal lobe meningioma with extension to the anterior ITF. This technique provides a minimally invasive approach for treating middle fossa lesions with anterior ITF extension.

Microvascular decompression for typical trigeminal neuralgia: Personal experience with intraoperative neuromonitoring with level-specific-CE-Chirp® brainstem auditory evoked potentials in preventing possible hearing loss.

BACKGROUND: Permanent hearing loss after posterior fossa microvascular decompression (MVD) for typical trigeminal neuralgia (TTN) is one of the possible complications of this procedure. Intraoperative brainstem auditory evoked potentials (BAEPs) are used for monitoring the function of cochlear nerve during cerebellopontine angle (CPA) microsurgery. Level-specific (LS)-CE-Chirp® BAEPs are the most recent evolution of classical click BAEP, performed both in clinical studies and during intraoperative neuromonitoring (IONM) of acoustic pathways during several neurosurgical procedures. METHODS: Since February 2016, we routinely use LS-CE-Chirp® BAEPs for monitoring the function of cochlear nerve during CPA surgery, including MVD for trigeminal neuralgia. From September 2011 to December 2018, 71 MVDs for TTN were performed in our department, 47 without IONM of acoustic pathways (Group A), and, from February 2016, 24 with LS-CE-Chirp BAEP (Group B). RESULTS: Two patients of Group A developed a permanent ipsilateral anacusia after MVD. In Group B, we did not observe any permanent acoustic deficit after surgery. In one case of Group B, during arachnoid dissection, intraoperative LS-CE-Chirp BAEP showed a temporary lag of V wave, resolved in 5 min after application of intracisternal diluted papaverine (0.3% solution without excipients). CONCLUSION: MVD is widely considered a definitive surgical procedure in the management of TTN. Even though posterior fossa MVD is a safe procedure, serious complications might occur. In particular, the use of IONM of acoustic pathways during MVD for TTN might contribute to prevention of postoperative hearing loss.

Typical Trigeminal Neuralgia: Comparison of Results between Patients Older and Younger than 65 Years Operated on with Microvascular Decompression by Retrosigmoid Approach.

OBJECTIVE: The incidence of typical trigeminal neuralgia (TN) increases with age, and neurologists and neurosurgeons frequently observe patients with this disorder at age 65 years or older. Microvascular decompression (MVD) of the trigeminal root entry zone in the posterior cranial fossa represents the etiological treatment of typical TN with the highest efficacy and durability of all treatments. This procedure is associated with possible risks (cerebellar hematoma, cranial nerve injury, stroke, and death) not seen with the alternative ablative procedures. Thus the safety of MVD in the elderly remains a topic of discussion. This study was conducted to determine whether MVD is a safe and effective treatment in older patients with TN compared with younger patients. METHODS: In this retrospective study, 28 patients older than 65 years (elderly cohort: mean age 70.9 ± 3.6 years) and 38 patients < 65 years (younger cohort: mean age 51.7 ± 6.3 years) underwent MVD via the keyhole retrosigmoid approach for type 1 TN (typical) or type 2a TN (typically chronic) from November 2011 to November 2017. A 75-year-old patient and three nonelderly patients with type 2b TN (atypical) were excluded. Elderly and younger cohorts were compared for outcome and complications. RESULTS: At a mean follow-up 26.0 ± 5.5 months, 25 patients of the elderly cohort (89.3%) reported a good outcome without the need for any medication for pain versus 34 (89.5%) of the younger cohort. Twenty-three elderly patients with type 1 TN were compared with 30 younger patients with type 1 TN, and no significant difference in outcomes was found (p > 0.05). Five elderly patients with type 2a TN were compared with eight younger patients with type 2a TN, and no significant difference in outcomes was noted (p > 0.05). There was one case of cerebrospinal fluid leak and one of a cerebellar hematoma, both in the younger cohort. Mortality was zero in both cohorts. CONCLUSIONS: On the basis of our experience and the international literature, age itself does not seem to represent a major contraindication of MVD for TN.

Hand-Held Thulium Laser Fiber and Ultrasonic Aspirator for Opening the Internal Auditory Canal During Acoustic Neuroma Microneurosurgery: Operative Technique.

Video 1 describes the technique of microsurgery removal of acoustic neuromas (ANs) using new technologies. The Flexible 2µ-Thulium hand-held laser fiber (Revolix jr, LISA laser products, 7 OHG, Berlin, Germany) and Sonopet Ultrasound Aspirator (Stryker, Kalamazoo, Michigan, USA) can be used for a safe and facilitated opening of the internal auditory canal (IAC). We illustrate the operative technique used on a surgical series of 111 cases operated on during the past 8 years, from July 2010 to July 2018. We studied 170 consecutive patients suffering from ANs who were operated on with a microsurgical technique by the key-hole retrosigmoid approach. In 111 cases the "Sonopet" Ultrasound Aspirator was used to open the IAC and a 2µ-Thulium laser fiber was used for cutting the dura mater of the posterior aspect of petrous bone and the IAC, and it was also used to perform tumor capsule incision. From December 2017 we started to check the removal of tumor inside the IAC with a flexible endoscope 4 mm × 65 cm, (Karl Storz GmbH, Tuttlingen, Germany) in order to detect possible tumoral residue and achieve a radical tumor resection in the fundus. The use of these new technologies seems to be safe and subjectively facilitates the opening of the IAC in AN microsurgery.

Hearing preservation after removal of small vestibular schwannomas by retrosigmoid approach: comparison of two different ABR neuromonitoring techniques.

BACKGROUND AND OBJECTIVE: Goals of small vestibular schwannoma (VS) microneurosurgery are as follows: radical resection, facial nerve (FN) preservation, and hearing preservation (HP). Microsurgical advances make HP possible in many patients with preoperative socially useful hearing (SUH). We evaluated postoperative HP in VS with maximum diameter < 2 cm monitored with two different auditory brainstem response (ABR) techniques. MATERIALS AND METHODS: Twenty-eight consecutive non-randomized patients with SUH suffering from small VS underwent keyhole microneurosurgery by retrosigmoid (RS) approach. Selection criteria are as follows: speech discrimination > 50%, pure tone audiogram < 50 dB loss (50/50 criterion; AAO-HNS classes A-B), maximum diameter < 2 cm. HP was attempted with intraoperative ABR, evoked by classical Click (16 cases, group 1) and LS-CE-Chirp® stimulus (12, group 2). RESULTS: Mean age was 47.5 years (16-75); average maximum diameter was 1.35 cm (0.5-1.9 mm). Total and nearly total resection (> 95%) was obtained in all, as confirmed by 24-48-h postoperative enhanced MRI. Mortality and major morbidity were 0. In all cases, FN was preserved; in 3, incomplete deficit recovered within few weeks. Socially useful HP (pre- and postoperatively) was 64.3% (18 of 28): 56.25% group 1 and 75% group 2 (p = NS). Postoperative ipsilateral deafness was observed in 5 cases of group 1 (p < 0.0001). Preoperative tinnitus had negative impact on HP (p < 0.05). CONCLUSIONS: Microsurgery can cure small growing VS with SUH. Our limited experience confirms that keyhole RS removal assisted by intraoperative ABR monitoring leads to valuable rates of SUH. LS-CE-Chirp-evoked ABRs allow a safe, effective, and clear neurophysiological feedback and are faster and, thus, more useful than the Click-ABR.

Anterior Cervical Fusion with Stand-alone Trabecular Metal Cages to Treat Cervical Myelopathy Caused by Degenerative Disk Disease. Observations in 88 Cases with Minimum 12-month Follow-up.

BACKGROUND: Anterior cervical fusion (ACF) with autologous bone was reported > 50 years ago. The continuous development of materials with elastic properties close to that of the cortical bone improves induction of osteogenesis and simplifies the technique of interbody fusion. To determine the safety and efficiency of stand-alone trabecular metal (TM) (or porous tantalum) cages for ACF, we performed a retrospective analysis of 88 consecutive patients with one-level or two-level degenerative disk disease (DDD) causing cervical myelopathy treated by interbody fusion with stand-alone TM cages. MATERIALS AND METHODS: During a 65-month period, 88 consecutive patients had ACF at 105 levels between C3 and C7. All surgeries involved one- or two-segmental DDD producing mild or severe cervical spine myelopathy, in 31 patients (35.2%), associated with unilateral or bilateral radiculopathy. We implanted all disk spaces with unfilled TM trapezoidal cages (Zimmer Biomet Spine, Broomfield, Colorado, United States). RESULTS: At a mean follow-up of 31 months (range: 12-65 months), 95.4% of patients had a good to excellent outcome, with subjective and objective improvement of myelopathy; the result was fair in two and poor in two other patients. Radicular pain and/or any deficits disappeared in 84 patients (95.4%) complaining of preoperative myeloradiculopathy. The fusion rate was 68.2% at 6 months and 100% at 1 year. Device fragmentation was never observed. In two cases, a second operation with removal of TM cages, corpectomy, expansion cages, and plating was necessary. CONCLUSIONS: TM cages appear to be safe and efficient for ACF in DDD patients with myelopathy. To confirm our preliminary impressions, larger studies with long-term follow-up are necessary.

Flexible Endoscopic-Assisted Microsurgical Radical Resection of Intracanalicular Vestibular Schwannomas by a Retrosigmoid Approach: Operative Technique.

The efficacy of endoscopic techniques in the surgical management of intracanalicular vestibular schwannomas (ICVSs) has been underlined in recent studies. An endoscopic- assisted retrosigmoid approach (EARSA) appears to be particularly suitable for achieving complete resection of an ICVS. In this study, we describe the surgical treatment of 3 cases of ICVS with an EARSA, highlighting the advantages and limitations of flexible endoscopy in accomplishing a safe radical resection with hearing preservation. Three patients with an ICVS underwent surgery via a flexible endoscopic-assisted microneurosurgical retrosigmoid approach. Flexible endoscopic assistance allowed the identification of residual tumor located in the most lateral portion of the fundus of the internal auditory canal in all cases. Endoscopic controls and further microsurgical resection were attempted, and complete surgical resection was achieved in all cases without the occurrence of postoperative facial or auditory nerve dysfunction. Flexible endoscopy appears to be particularly useful and safe in the surgical management of ICVS by microneurosurgery via an EARSA.

Cystic Progression of a Cavernous Malformation at the Level of the Trigeminal Root Entry Zone Presenting With Sudden Onset of Trigeminal Neuralgia.

BACKGROUND: Cavernous malformations (CM) in the cerebellopontine angle (CPA) are rare, and most of them are solid and extend from the internal auditory canal into the CPA. In contrast, cystic CM arising in the CPA and not involving the internal auditory canal and dura of the skull base are extremely rare. The authors present an uncommon large cystic progression of a cavernous malformation at the level of the trigeminal root entry zone evolving to severe trigeminal neuralgia and brainstem compression. METHODS: A 62-year-old female presented a sudden onset of left trigeminal neuralgia, caused by a large cystic lesion at the level of the root entry zone of the left 5th nerve. On neurological examination, she showed slight gait ataxia and hypoesthesia on the left hemiface (on the first and second trigeminal branches). Other cranial nerves were in order. Magnetic resonance imaging showed a large cystic intracranial mass, with a small solid portion, leading to brainstem compression. RESULTS: Microsurgical removal of the lesion was performed via retrosigmoid approach, with intraoperative monitoring of somato-sensory evoked potentials, facial, and cochlear nerves. The posterior-medial portion of the lesion was solid, whereas the main portion was cystic, containing xanthochromic fluid. The small solid lesion continued with a thin capsule of a large cyst adherent to brainstem, cerebellar hemisphere, and trigeminal nerve entry zone. A big draining vein arising from the solid part of the lesion runned parallel to brainstem. The mass was piecemeal totally removed.After surgery the patient recovered both left trigeminal neuralgia and hypoesthesia; ataxia was significantly relieved too. Postoperative magnetic resonance imaging confirmed the total removal. Histopathological features were consistent with a CM. At 6-month follow-up, patient's symptoms at the presentation had resolved. CONCLUSION: The authors present a very rare patient of large cystic cavernous malformation at the level of the trigeminal root entry zone presenting with sudden onset of trigeminal neuralgia. Even if it has not established imaging features, a cystic cavernoma of the cerebello-pontine angle may be suspected when a cystic mass is present, not involving the internal acoustic meatus nor the skull base dura mater. Careful microneurosurgical technique and monitoring of cranial nerves allow good long-term results.

Vestibular schwannoma and hearing preservation: Usefulness of level specific CE-Chirp ABR monitoring. A retrospective study on 25 cases with preoperative socially useful hearing.

BACKGROUND AND OBJECTIVES: Decision-making regarding the therapy of vestibular schwannoma (VS) changed over the last decades, during which curative microsurgery has been promoted. Goals of VS microsurgery are: extensive resection, facial nerve (FN) preservation and, in selected cases, hearing preservation (HP). The aim of this study is to evaluate postoperative HP with reference to tumor size in patients operated on with Level Specific (LS)-CE-Chirp® ABR monitoring. PATIENTS AND METHODS: Twentyfive consecutive patients with socially useful hearing (SUH) underwent VS microneurosurgery by retrosigmoid (RS) approach. Selection criteria were: pure tone audiogram <50dB loss and speech discrimination score >50% (50/50 criterion; AAO-HNS class A-B). In relation to maximum diameter, we identified 2 size-groups: A) ≤2cm (13 cases); B) >2cm (12 cases). HP attempt was assisted by intraoperative ABR evoked by LS CE-Chirp® acoustic stimuli. RESULTS: Mean age was 44,3 years (20-64); average maximum diameter 2,04cm (8 40mm). Total and nearly-total (>95%) resection was possible in all. Mortality and major morbidity were zero. In all, FN was anatomically and functionally preserved; in 10 an incomplete FN deficit (House-Brackmann II and III) was followed by complete recovery (House-Brackmann I). SUH preservation rate was 52%, with significant differences in relation to size: 61,5% group A and 41,7% group B (p = 0,014). Postoperative AAO-HNS C (serviceable) hearing was observed in 36%, deafness in 12%. CONCLUSION: Microsurgery represents a valid therapeutic option for small growing VS with SUH. Our data confirm that RS removal of VS with intraoperative ABR monitoring allows good rate of SUH preservation, especially if maximum diameter does not exceed 2cm. LS-CE-Chirp ABR represent a safe and effective method for monitoring cochlear nerve, with fast and clear intraoperative neurophysiological feedback.

Position and Course of Facial Nerve and Postoperative Facial Nerve Results in Vestibular Schwannoma Microsurgery.

OBJECTIVE: To investigate the variation in the position and course of the facial nerve (FN) in patients undergoing vestibular schwannoma (VS) microsurgery by the keyhole retrosigmoid approach and the relationship between FN position and postoperative facial results. METHODS: The series consists of 100 patients who underwent VS microsurgery during a 5-year period in whom the position and course of the FN could be confirmed by direct stimulation. The course of the FN was classified into 4 patterns according to its position: anterior (ventral) surface of the tumor (A), anterior-superior (AS), anterior-inferior (AI), and dorsal (D). RESULTS: The distribution of patterns was as follows: AS in 48 cases, A in 31, AI in 21, and D in zero. For tumors <1.5 cm, the AS pattern was most common (68.4%). For tumors ≥1.5 cm, the proportion of A and AI positions increased (31.4% and 25.5%). Significant differences were observed between position and course patterns of the FN and postoperative nerve results. Patients with AS and AI patterns had better House-Brackmann FN function compared with patients with the A pattern (P < 0.05). Moreover, in tumors >3.0 cm, the FN tended to adhere strongly to the tumor capsule, and postoperative facial deficits were more frequent (P < 0.05). CONCLUSIONS: The AS pattern was most common for smaller VSs. The A position and course and adhesion of the FN to the tumor capsule were the 2 factors most strongly associated with worse postoperative FN result.

Surgical treatment of degenerative and traumatic spinal diseases with expandable screws in patients with osteoporosis: 2-year follow-up clinical study.

OBJECTIVE Pedicle screw instrumentation of the osteoporotic spine carries an increased risk of screw loosening, pullout, and fixation failure. A variety of techniques have been used clinically to improve pedicle screw fixation in the presence of compromised bone. Pedicle screws may be augmented with cement, but this may lead to cement leakage and result in disastrous consequences. To avoid these complications, a multiaxial expandable pedicle screw has been developed. This was a prospective, single-center study designed to evaluate the clinical results of patients with osteoporosis with traumatic and degenerative spinal diseases treated with expandable pedicle screws. METHODS Thirty-three patients (mean age 61.4 years) with osteoporosis and traumatic or degenerative spinal diseases underwent spinal posterior fixation with expandable screws. Preoperative and postoperative visual analog scale (VAS) for pain and Oswestry Disability Index (ODI) questionnaire scores were obtained. The immediate postoperative screw position was measured and compared with the final position on lateral plain radiographs and axial CT scans at the 1- and 2-year follow-up examinations. RESULTS A total of 182 pedicle screws were used, including 174 expandable and 8 regular screws. The mean preoperative patient VAS score improved from 8.2 to 3.6 after surgery. The mean ODI score improved from 83.7% before surgery to 29.7% after the operation and to 36.1% at the final follow-up. No screw migration had occurred at the 1-year follow-up, but 1 screw breakage/migration was visualized on spinal radiography at the 2-year follow-up. CONCLUSIONS The results of this study show that the multiaxial expandable pedicle screw is a safe and practical technique for patients with osteoporosis and various spinal diseases and adds a valuable tool to the armamentarium of spinal instrumentation.

Safety and usefulness of flexible hand-held laser fibers in microsurgical removal of acoustic neuromas (vestibular schwannomas).

AIMS: We performed a retrospective non-randomized study to analyze the results of microsurgery of acoustic neuromas (AN) using two different flexible hand-held laser fibers, CO2 (Omniguide(®)) and 2µ-Thulium (Revolix jr(®)). METHODS: From September 2010 to June 2015, 84 patients suffering from AN have been operated on with microsurgical technique via retrosigmoid (RS) approach. In 42 cases tumor resection was performed with the assistance of hand-held flexible laser (L-group): in 8 cases CO2-fiber and in 34 2µ-Thulium-fiber. Fortytwo patients, operated on without laser-assistance, were used as comparison group (C-group) (matched-pair-technique). Facial nerve function was assessed with the House-Brackmann (HB) scale preoperatively, 1 week postoperatively, and 6-month or more after surgery. RESULTS: Overall time from incision to skin suture changed in relation to size of tumor (165-575min) and was not affected by the use of laser. In 2 cases preoperative facial nerve palsy was observed. In the remaining 82 cases, at 6-month follow-up facial nerve preservation rate (HB I) was 90.2%. Hearing preservation rate (AAO-HNS A/B classes) was 68.4% (26 out of 38). Adopting a 0-3-scale, the mean surgeon satisfaction rate of usefulness of laser fiber was 2.64. CONCLUSIONS: The use of a hand-held flexible laser fiber in AN-microsurgery seems to be safe and subjectively facilitates tumor resection especially in "difficult" conditions (e.g., highly vascularized and hard tumors). In this limited retrospective trial, the good functional outcome following conventional microsurgery had not further improved, nor the surgical time reduced by laser. Focusing its use on "difficult" (large and vascularized) cases may lead to different results in future.

Underlay hourglass-shaped autologous pericranium duraplasty in "key-hole" retrosigmoid approach surgery: Technical report.

BACKGROUND: Cerebrospinal fluid (CSF) leakages represent a major complication of skull base surgery. Watertight dural suture is challenging, and different ways to reinforce it have been proposed. Since 6 months, we use locally harvested autologous pericranium graft for dural repair in retrosigmoid approach. METHODS: Retrospectively, we analyzed 27 patients operated on with key-hole retrosigmoid approach from May 2014. In all, autologous pericranium was harvested and inserted as an underlay "hourglass-shaped" plug under the dura plane and stitched to dura. Surgical patch and sealant were used for augmentation. Complications considered were new neurological symptoms, surgical site infections, meningitis, CSF-leaks, and pseudomeningocele. RESULTS: Indications included tumor (16 cases), microvascular decompression (10 cases), and hemorrhagic cerebellar arteriovenous malformation (1 case). Surgical site infections, meningitis, and CSF leaks have never been observed. One neurofibromatosis type 2 patient operated on for large acoustic neuroma developed an asymptomatic pseudomeningocele, disappeared on 3-month magnetic resonance imaging follow-up. CONCLUSIONS: In our series, autologous pericranium inserted and stitched as an underlay hourglass-shaped plug, augmented with surgical patch pieces and dural sealant seemed to be safe and effective for dural repair in "key-hole" retrosigmoid approach. With this technique, we obtained low complication rate, similar to the best current results of available literature.