Search Results

You are looking at 1 - 10 of 10 items for

  • Author or Editor: Alexander Micko x
  • All content x
Clear All Modify Search
Full access

Alexander S. G. Micko, Adelheid Wöhrer, Stefan Wolfsberger, and Engelbert Knosp

OBJECT

An important prognostic factor for the surgical outcome and recurrence of a pituitary adenoma is its invasiveness into parasellar tissue, particularly into the space of the cavernous sinus (CS). The aims of this study were to reevaluate the existing parasellar classifications using an endoscopic technique and to evaluate the clinical and radiological outcomes associated with each grade.

METHODS

The authors investigated 137 pituitary macroadenomas classified radiologically at least on one side as Grade 1 or higher (parasellar extension) and correlated the surgical findings using an endoscopic technique, with special reference to the invasiveness of the tumor into the CS. In each case, postoperative MRI was performed to evaluate the gross-total resection (GTR) rate and the rate of endocrinological remission (ER) in functioning adenomas.

RESULTS

The authors found a 16% rate of CS invasion during surgery for these macroadenomas. Adenomas radiologically classified as Grade 1 were found to be invasive in 1.5%, and the GTR/ER rate was 83%/88%. For Grade 2 adenomas, the rate of invasion was 9.9%, and the GTR/ER rate was 71%/60%. For Grade 3 adenomas, the rate of invasion was 37.9%, and the GTR/ER rate was 75%/33%. When the superior compartment of the CS (Grade 3A) was involved, the authors found a rate of invasion that was lower (p < 0.001) than that when the inferior compartment was involved (Grade 3B). The rate of invasion in Grade 3A adenomas was 26.5% with a GTR/ER rate of 85%/67%, whereas for Grade 3B adenomas, the rate of surgically observed invasion was 70.6% with a GTR/ER rate of 64%/0%. All of the Grade 4 adenomas were invasive, and the GTR/ER rate was 0%.

A comparison of microscopic and endoscopic techniques revealed no difference in adenomas with Grade 1 or 4 parasellar extension. In Grade 2 adenomas, however, the CS was found by the endoscopic technique to be invaded in 9.9% and by microscopic evaluation to be invaded in 88% (p < 0.001); in Grade 3 adenomas, the difference was 37.9% versus 86%, respectively (p = 0.002). Grade 4 adenomas had a statistically significant lower rate of GTR than those of all the other grades. In case of ER only, Grade 1 adenomas had a statistically significant higher rate of remission than did Grade 3B and Grade 4 adenomas.

CONCLUSIONS

The proposed classification proved that with increasing grades, the likelihood of surgically observed invasion rises and the chance of GTR and ER decreases. The direct endoscopic view confirmed the low rate of invasion of Grade 1 adenomas but showed significantly lower rates of invasion in Grade 2 and 3 adenomas than those previously found using the microscopic technique. In cases in which the intracavernous internal carotid artery was encased (Grade 4), all the adenomas were invasive and the GTR/ER rate was 0%/0%. The authors suggest the addition of Grades 3A and 3B to distinguish the strikingly different outcomes of adenomas invading the superior CS compartments and those invading the inferior CS compartments.

Restricted access

Ayguel Wurzer, Georgi Minchev, Claudia Cervera-Martinez, Alexander Micko, Gernot Kronreif, and Stefan Wolfsberger

OBJECTIVE

Electromagnetic (EM) navigation provides the advantages of continuous guidance and tip-tracking of instruments. The current solutions for patient reference trackers are suboptimal, as they are either invasively screwed to the bone or less accurate if attached to the skin. The authors present a novel EM reference method with the tracker rigidly but not invasively positioned inside the nasal cavity.

METHODS

The nasal tracker (NT) consists of the EM coil array of the AxiEM tracker plugged into a nasal tamponade, which is then inserted into the inferior nasal meatus. Initially, a proof-of-concept study was performed on two cadaveric skull bases. The stability of the NT was assessed in simulated surgical situations, for example, prone, supine, and lateral patient positioning and skin traction. A deviation ≤ 2 mm was judged sufficiently accurate for clinical trial. Thus, a feasibility study was performed in the clinical setting. Positional changes of the NT and a standard skin-adhesive tracker (ST) relative to a ground-truth reference tracker were recorded throughout routine surgical procedures. The accuracy of the NT and ST was compared at different stages of surgery.

RESULTS

Ex vivo, the NT proved to be highly stable in all simulated surgical situations (median deviation 0.4 mm, range 0.0–2.0 mm). In 13 routine clinical cases, the NT was significantly more stable than the ST (median deviation at procedure end 1.3 mm, range 0.5–3.0 mm vs 4.0 mm, range 1.2–11.2 mm, p = 0.002). The loss of accuracy of the ST was highest during draping and flap fixation.

CONCLUSIONS

Application of the EM endonasal patient tracker was found to be feasible with high procedural stability ex vivo as well as in the clinical setting. This innovation combines the advantages of high precision and noninvasiveness and may, in the future, enhance EM navigation for neurosurgery.

Restricted access

Alexander Micko, Johannes Oberndorfer, Wolfgang J. Weninger, Greisa Vila, Romana Höftberger, Stefan Wolfsberger, and Engelbert Knosp

OBJECTIVE

Parasellar growth is one of the most important prognostic variables of pituitary adenoma surgery, with adenomas regarded as not completely resectable if they invade the cavernous sinus (CS) but potentially curable if they displace CS structures. This study was conducted to correlate surgical treatment options and outcomes to the different biological behaviors (invasion vs displacement) of adenomas with parasellar extension into the superior or inferior CS compartments or completely encasing the carotid artery (Knosp high grades 3A, 3B, and 4).

METHODS

This was a retrospective cohort analysis of 106 consecutive patients with Knosp high-grade pituitary adenomas with parasellar extension who underwent surgery via a primary endoscopic transsphenoidal approach between 2003 and 2017. Biological tumor characteristics (surgical status of invasiveness and tumor texture, 2017 WHO classification, proliferation rate), extent of resection, and complication rate were correlated with parasellar extension grades 3A, 3B, and 4 on preoperative MRI studies.

RESULTS

Invasiveness was significantly less common in grade 3A (44%) than in grade 3B (72%, p = 0.037) and grade 4 (100%, p < 0.001) adenomas. Fibrous tumor texture was significantly more common in grade 4 (52%) compared to grade 3A (20%, p = 0.002), but not compared to grade 3B (28%) adenomas. Functioning macroadenomas had a significantly higher rate of invasiveness than nonfunctioning adenomas (91% vs 55%, p = 0.002). Mean proliferation rate assessed by MIB-1 was > 3% in all groups but without significant difference between the groups (grade 3A, 3.2%; 3B, 3.9%; 4, 3.7%). Rates of endocrine remission/gross-total resection were significantly higher in grade 3A (64%) than in grade 3B (33%, p = 0.021) and grade 4 (0%, p < 0.001) adenomas. In terms of complication rates, no significant difference was observed between grades.

CONCLUSIONS

According to the authors’ data, the biological behavior of pituitary adenomas varies significantly between parasellar extension patterns. Adenomas with extension into the superior CS compartment have a lower rate of invasive growth than adenomas extending into the inferior CS compartment or encasing the carotid artery. Consequently, a significantly higher rate of remission can be achieved in grade 3A than in grade 3B and grade 4 adenomas. Therefore, the distinction into grades 3A, 3B, and 4 is of importance for prediction of adenoma invasion and surgical treatment considerations.

Restricted access

Alexander Micko, Arthur Hosmann, Aygül Wurzer, Svenja Maschke, Wolfgang Marik, Engelbert Knosp, and Stefan Wolfsberger

OBJECTIVE

The transsphenoidal route to pituitary adenomas challenges surgeons because of the highly variable sinunasal anatomy. Orientation may be improved if the appropriate information is provided intraoperatively by image guidance. The authors developed an advanced image guidance protocol dedicated to sinunasal surgery that extracts information from multiple modalities and forms it into a single image that includes fine sinunasal structures and arteries.

The aim of this study was to compare the advantages of this novel image guidance protocol with the authors’ previous series, with emphasis on anatomical structures visualized and complication rate.

METHODS

This retrospective analysis comprised 200 patients who underwent surgery for pituitary adenoma via a transnasal transsphenoidal endoscopic approach. The authors’ standard image guidance protocol consisting of CT for solid bone, T1CEMRI for soft tissues, and MRA for the carotid artery was applied in 100 consecutive cases. The advanced image guidance protocol added a first-hit ray casting of the CT scan for visualization of fine sinunasal structures, and adjustments to the MRA to visualize the sphenopalatine artery (SPA) were applied in a subsequent 100 consecutive cases.

RESULTS

A patent sphenoid ostium—i.e., an ostium not covered by a mucosal layer—was visualized significantly more often by the advanced protocol than the standard protocol (89% vs 40%, p < 0.001) in primary surgeries. The SPA and its branches were only visualized by the advanced protocol (87% and 91% of cases in primary surgeries and reoperations, respectively) and not once by the standard protocol. The number of visualized complete and incomplete sphenoid septations matched significantly more commonly with the surgical view when using the advanced protocol than the standard protocol at primary operation (mean 1.9 vs 1.6, p < 0.001). However, in 25% of all cases a complex and not a simple sinus anatomy was present. In comparison with the intraoperative results, a complex sphenoid sinus anatomy was always detected by the advanced but not by the standard protocol (25% vs 8.5%, p = 0.001).

Furthermore, application of the advanced protocol reduced the cumulative rate of complications (25% vs 18% [standard vs advanced group]). Although an overall significant difference could not be determined (p = 0.228), a subgroup analysis of reoperations (35/200) revealed a significantly lower rate of complications in the advanced group (5% vs 30%, p = 0.028).

CONCLUSIONS

The data show that the advanced image guidance protocol could intraoperatively visualize the fine sinunasal sinus structures and small arteries with a high degree of detail. By improving intraoperative orientation, this may help to reduce the rate of complications in endoscopic transsphenoidal surgery, especially in reoperations.

Restricted access

Alexander Micko, Thomas Rötzer, Romana Hoftberger, Greisa Vila, Johannes Oberndorfer, Josa M. Frischer, Engelbert Knosp, and Stefan Wolfsberger

OBJECTIVE

According to the latest WHO classification of tumors of endocrine organs in 2017, plurihormonal adenomas are subclassified by their transcription factor (TF) expression. In the group of plurihormonal adenomas with unusual immunohistochemical combinations (PAWUC), the authors identified a large fraction of adenomas expressing TFs for gonadotroph adenoma (TFGA) cells in addition to other TFs. The aim of this study was to compare clinicopathological parameters of PAWUC with TFGA expression to gonadotroph adenomas that only express TFGA.

METHODS

This retrospective single-center series comprises 73 patients with TFGA-positive pituitary adenomas (SF1, GATA3, estrogen receptor α): 22 PAWUC with TFGA (TFGA-plus group) and 51 with TFGA expression only (TFGA-only group). Patient characteristics, outcome parameters, rate of invasiveness (assessed by direct endoscopic inspection), and MIB1 and MGMT status were compared between groups.

RESULTS

Patients in the TFGA-plus group were significantly younger than patients in the TFGA-only group (age 46 vs 56 years, respectively; p = 0.007). In the TFGA-only group, pituitary adenomas were significantly larger (diameter 25 vs 18.3 mm, p = 0.002). Intraoperatively, signs of invasiveness were significantly more common in the TFGA-plus group than in the TFGA-only group (50% vs 16%, p = 0.002). Gross-total resection was significantly lower in the nonfunctioning TFGA-plus group than in the TFGA-only group (44% vs 86%, p = 0.004). MIB1 and MGMT status showed no significant difference between groups.

CONCLUSIONS

These data suggest a more aggressive behavior of TFGA-positive adenomas if an additional TF is expressed within the tumor cells. Shorter radiographic surveillance and earlier consideration for retreatment should be recommended in these adenoma types.

Free access

Tyler Cardinal, Martin J. Rutkowski, Alexander Micko, Mark Shiroishi, Chia-Shang Jason Liu, Bozena Wrobel, John Carmichael, and Gabriel Zada

OBJECTIVE

Acromegaly is a disease of acral enlargement and elevated serum levels of insulin-like growth factor–1 (IGF-1) and growth hormone (GH), usually caused by a pituitary adenoma. A lack of consensus on factors that reliably predict outcomes in acromegalic patients following endoscopic endonasal transsphenoidal surgery (EETS) warrants additional investigation.

METHODS

The authors identified 52 patients with acromegaly who underwent an endoscopic endonasal approach (EEA) for resection of a GH-secreting pituitary adenoma. Preoperative and postoperative tumor and endocrinological characteristics such as tumor size, invasiveness, and GH/IGF-1 levels were evaluated as potential indicators of postoperative hormonal remission. Endocrinological remission was defined as postoperative IGF-1 levels at or below the age- and sex-normalized values.

RESULTS

The 52 patients had a mean age of 50.7 ± 13.4 years and a mean follow-up duration of 24.4 ± 19.1 months. Ten patients (19%) had microadenomas and 42 (81%) had macroadenomas. Five patients (9.6%) had giant adenomas. Forty-four tumors (85%) had extrasellar extension, with 40 (77%) exhibiting infrasellar invasion, 18 (35%) extending above the sella, and 7 (13%) invading the cavernous sinuses. Thirty-six patients (69%) underwent gross-total resection (GTR; mean maximal tumor diameter 1.47 cm), and 16 (31%) underwent subtotal resection (STR; mean maximal tumor diameter 2.74 cm). Invasive tumors were significantly larger, and Knosp scores were negatively correlated with GTR. Thirty-eight patients (73%) achieved hormonal remission after EEA resection alone, which increased to 87% with adjunctive medical therapy. Ninety percent of patients with microadenomas and 86% of patients with macroadenomas achieved hormonal remission. Preoperative IGF-1 and postoperative day 1 (POD1) GH levels were inversely correlated with hormonal remission. Postoperative CSF leakage occurred in 2 patients (4%), and none experienced vision loss, death, or injury to internal carotid arteries or cranial nerves.

CONCLUSIONS

Endoscopic transsphenoidal resection of GH-secreting pituitary adenomas is a safe and highly effective treatment for achieving hormonal remission and tumor control in up to 87% of patients with acromegaly when combined with postoperative medical therapy. Patients with lower preoperative IGF-1 and POD1 GH levels, with less invasive pituitary adenomas, and who undergo GTR are more likely to achieve postoperative biochemical remission.

Restricted access

Alexander Micko, Benjamin I. Rapoport, Brett E. Youngerman, Reginald P. Fong, Jennifer Kosty, Andrew Brunswick, Shane Shahrestani, Gabriel Zada, and Theodore H. Schwartz

OBJECTIVE

Incomplete resection of skull base pathology may result in local tumor recurrence. This study investigates the utility of 5-aminolevulinic acid (5-ALA) fluorescence during endoscopic endonasal approaches (EEAs) to increase visibility of pathologic tissue.

METHODS

This retrospective multicenter series comprises patients with planned resection of an anterior skull base lesion who received preoperative 5-ALA at two tertiary care centers. Diagnostic use of a blue light endoscope was performed during EEA for all cases. Demographic and tumor characteristics as well as fluorescence status, quality, and homogeneity were assessed for each skull base pathology.

RESULTS

Twenty-eight skull base pathologies underwent blue-light EEA with preoperative 5-ALA, including 15 pituitary adenomas (54%), 4 meningiomas (14%), 3 craniopharyngiomas (11%), 2 Rathke’s cleft cysts (7%), as well as plasmacytoma, esthesioneuroblastoma, and sinonasal squamous cell carcinoma. Of these, 6 (21%) of 28 showed invasive growth into surrounding structures such as dura, bone, or compartments of the cavernous sinus. Tumor fluorescence was detected in 2 cases (7%), with strong fluorescence in 1 tuberculum sellae meningioma and vague fluorescence in 1 pituicytoma. In all other cases fluorescence was absent. Faint fluorescence of the normal pituitary gland was seen in 1 (7%) of 15 cases. A comparison between the particular tumor entities as well as a correlation between invasiveness, WHO grade, Ki-67, and positive fluorescence did not show any significant association.

CONCLUSIONS

With the possible exception of meningiomas, 5-ALA fluorescence has limited utility in the majority of endonasal skull base surgeries, although other pathology may be worth investigating.

Restricted access

Georgi Minchev, Gernot Kronreif, Wolfgang Ptacek, Christian Dorfer, Alexander Micko, Svenja Maschke, Federico G. Legnani, Georg Widhalm, Engelbert Knosp, and Stefan Wolfsberger

OBJECTIVE

As decisions regarding tumor diagnosis and subsequent treatment are increasingly based on molecular pathology, the frequency of brain biopsies is increasing. Robotic devices overcome limitations of frame-based and frameless techniques in terms of accuracy and usability. The aim of the present study was to present a novel, minimally invasive, robot-guided biopsy technique and compare the results with those of standard burr hole biopsy.

METHODS

A tubular minimally invasive instrument set was custom-designed for the iSYS-1 robot-guided biopsies. Feasibility, accuracy, duration, and outcome were compared in a consecutive series of 66 cases of robot-guided stereotactic biopsies between the minimally invasive (32 patients) and standard (34 patients) procedures.

RESULTS

Application of the minimally invasive instrument set was feasible in all patients. Compared with the standard burr hole technique, accuracy was significantly higher both at entry (median 1.5 mm [range 0.2–3.2 mm] vs 1.7 mm [range 0.8–5.1 mm], p = 0.008) and at target (median 1.5 mm [range 0.4–3.4 mm] vs 2.0 mm [range 0.8–3.9 mm], p = 0.019). The incision-to-suture time was significantly shorter (median 30 minutes [range 15–50 minutes] vs 37.5 minutes [range 25–105 minutes], p < 0.001). The skin incision was significantly shorter (median 16.3 mm [range 12.7–23.4 mm] vs 28.4 mm [range 20–42.2 mm], p = 0.002). A diagnostic tissue sample was obtained in all cases.

CONCLUSIONS

Application of the novel instrument set was feasible in all patients. According to the authors’ data, the minimally invasive robot-guidance procedure can significantly improve accuracy, reduce operating time, and improve the cosmetic result of stereotactic biopsies.

Full access

Georgi Minchev, Gernot Kronreif, Mauricio Martínez-Moreno, Christian Dorfer, Alexander Micko, Aygül Mert, Barbara Kiesel, Georg Widhalm, Engelbert Knosp, and Stefan Wolfsberger

OBJECTIVE

Robotic devices have recently been introduced in stereotactic neurosurgery in order to overcome the limitations of frame-based and frameless techniques in terms of accuracy and safety. The aim of this study is to evaluate the feasibility and accuracy of the novel, miniature, iSYS1 robotic guidance device in stereotactic neurosurgery.

METHODS

A preclinical phantom trial was conducted to compare the accuracy and duration of needle positioning between the robotic and manual technique in 162 cadaver biopsies. Second, 25 consecutive cases of tumor biopsies and intracranial catheter placements were performed with robotic guidance to evaluate the feasibility, accuracy, and duration of system setup and application in a clinical setting.

RESULTS

The preclinical phantom trial revealed a mean target error of 0.6 mm (range 0.1–0.9 mm) for robotic guidance versus 1.2 mm (range 0.1–2.6 mm) for manual positioning of the biopsy needle (p < 0.001). The mean duration was 2.6 minutes (range 1.3–5.5 minutes) with robotic guidance versus 3.7 minutes (range 2.0–10.5 minutes) with manual positioning (p < 0.001). Clinical application of the iSYS1 robotic guidance device was feasible in all but 1 case. The median real target error was 1.3 mm (range 0.2–2.6 mm) at entry and 0.9 mm (range 0.0–3.1 mm) at the target point. The median setup and instrument positioning times were 11.8 minutes (range 4.2–26.7 minutes) and 4.9 minutes (range 3.1–14.0 minutes), respectively.

CONCLUSIONS

According to the preclinical data, application of the iSYS1 robot can significantly improve accuracy and reduce instrument positioning time. During clinical application, the robot proved its high accuracy, short setup time, and short instrument positioning time, as well as demonstrating a short learning curve.

Restricted access

Martin J. Rutkowski, Ki-Eun Chang, Tyler Cardinal, Robin Du, Ali R. Tafreshi, Daniel A. Donoho, Andrew Brunswick, Alexander Micko, Chia-Shang J. Liu, Mark S. Shiroishi, John D. Carmichael, and Gabriel Zada

OBJECTIVE

Pituitary adenoma (PA) consistency, or texture, is an important intraoperative characteristic that may dictate operative dissection techniques and/or instruments used for tumor removal during endoscopic endonasal approaches (EEAs). The impact of PA consistency on surgical outcomes has yet to be elucidated.

METHODS

The authors developed an objective 5-point grading scale for PA consistency based on intraoperative characteristics, including ease of tumor debulking, manipulation, and instrument selection, ranging from cystic/hemorrhagic tumors (grade 1) to calcified tumors (grade 5). The proposed grading system was prospectively assessed in 306 consecutive patients who underwent an EEA for PAs, and who were subsequently analyzed for associations with surgical outcomes, including extent of resection (EOR) and complication profiles.

RESULTS

Institutional database review identified 306 patients who underwent intraoperative assessment of PA consistency, of which 96% were macroadenomas, 70% had suprasellar extension, and 44% had cavernous sinus invasion (CSI). There were 214 (69.9%) nonfunctional PAs and 92 functional PAs (31.1%). Distribution of scores included 15 grade 1 tumors (4.9%), 112 grade 2 tumors (36.6%), 125 grade 3 tumors (40.8%), 52 grade 4 tumors (17%), and 2 grade 5 tumors (0.7%). Compared to grade 1/2 and grade 3 PAs, grade 4/5 PAs were significantly larger (22.5 vs 26.6 vs 27.4 mm, p < 0.01), more likely to exhibit CSI (39% vs 42% vs 59%, p < 0.05), and trended toward nonfunctionality (67% vs 68% vs 82%, p = 0.086). Although there was no association between PA consistency and preoperative headaches or visual dysfunction, grade 4/5 PAs trended toward preoperative (p = 0.058) and postoperative panhypopituitarism (p = 0.066). Patients with preoperative visual dysfunction experienced greater improvement if they had a grade 1/2 PA (p < 0.05). Intraoperative CSF leaks were noted in 32% of cases and were more common with higher-consistency-grade tumors (p = 0.048), although this difference did not translate to postoperative CSF leaks. Gross-total resection (%) was more likely with lower PA consistency score as follows: grade 1/2 (60%), grade 3 (50%), grade 4/5 (44%; p = 0.045). Extracapsular techniques were almost exclusively performed in grade 4/5 PAs. Assignment of scores showed low variance and high reproducibility, with an intraclass correlation coefficient of 0.905 (95% CI 0.815–0.958), indicating excellent interrater reliability.

CONCLUSIONS

These findings demonstrate clinical validity of the proposed intraoperative grading scale with respect to PA subtype, neuroimaging features, EOR, and endocrine complications. Future studies will assess the relation of PA consistency to preoperative MRI findings to accurately predict consistency, thereby allowing the surgeon to tailor the exposure and prepare for varying resection strategies.