Intraoperative Anatomic Landmarks Research Articles

Multicenter survey about leg length discrepancy and total hip arthroplasty: preoperative and intraoperative management

BackgroundWe created a multicenter survey for Italian orthopedic surgeons on how they approach leg length discrepancy (LLD) when dealing with primary total hip arthroplasty. Aim of the study was to show how surgeons manage LLD and follow the literature recommendations during clinical practice.MethodsThe survey was composed of 25 questions divided into four sections: 1—surgeon’s profile, 2—preoperative and 3—intraoperative evaluation, and 4—postoperative management. In this paper, we report results to answer Sects. 1 and 2. Absolute and relative frequencies of answers to Sects. 2 and 3 are reported. We divided the participants in subgroups based on the “surgeon’s profile” and evaluated difference in the answers given.ResultsAbsolute and relative frequencies demonstrate low agreement among participants in all phases of LLD management. We demonstrated a statistically significant difference based on the surgeon’s profile regarding these questions: radiographic measure of LLD depending on working experience, p = 0.008; digital planning based on surgeons’ age, p < 0.001, and workplace, p = 0.026; intraoperative anatomical landmarks based on numbers of procedures per year, p = 0.020; and use of intraoperative X-rays based on working experience, p = 0.002.ConclusionsLLD is a debated topic with no definitive recommendations. Many decisions still depend on tradition and surgeons’ preference.

Accuracy of acetabular cup positioning in robotic-assisted total hip arthroplasty: a CT-based evaluation.

Robot-assisted instrumentation during total hip arthroplasty (THA) has the potential to improve acetabular cup positioning. This study aimed to evaluate the precision of robotic-arm-assisted THA (rTHA) and assess whether the system can provide accurate cup positioning comparable to conventional THA (cTHA). A single-center prospective cohort study consisting of 151 patients who underwent THA (108 rTHA and 43 cTHA). The robotically assisted system was used to match the postoperative computed tomography (CT) image of the pelvis with the planned and intraoperative anatomical landmarks. The cTHA cohort underwent hip replacement using the standard manual procedure, with acetabular component locations assessed during and after surgery. The rTHA cohort was significantly younger, but no other significant differences were found between the two cohorts in preoperative baseline data. In rTHA cohort, the planned inclination (40.0±0.3°) closely matched the intraoperative (40.2±2.7°; p=0.54) and postoperative (40.7±4.0°; p=0.07) measurements. However, anteversion showed a significant increase from planned (19.4±1.5°) to postoperative CT scan (28.7±7.0°; p<0.001). There was evidence of proportional bias in the measurements (p<0.001). In the cTHA cohort, the mean inclination (43.1±5.1°) did not show any significant change between the preoperative plans and postoperative assessments (p=0.12); however, there was a remarkable change in the mean anteversion (17.6±6.4°) between postoperative measurements and the preoperative plans (p<0.001). The average anteversion in the preoperative plans did not differ remarkably between the rTHA and cTHA cohorts. However, the average inclination was substantially different between the two cohorts (p<0.001). Both groups had no significant differences in the proportion of cups outside the referenced safe zones. The results suggest that while robotic-assisted guidance ensures consistent cup inclination, there may be more variability in achieving the planned anteversion, which warrants further investigation into the factors influencing postoperative changes in acetabular orientation.

Development of a cross-artificial intelligence system for identifying intraoperative anatomical landmarks and surgical phases during laparoscopic cholecystectomy.

Attention to anatomical landmarks in the appropriate surgical phase is important to prevent bile duct injury (BDI) during laparoscopic cholecystectomy (LC). Therefore, we created a cross-AI system that works with two different AI algorithms simultaneously, landmark detection and phase recognition. We assessed whether landmark detection was activated in the appropriate phase by phase recognition during LC and the potential contribution of the cross-AI system in preventing BDI through a clinical feasibility study (J-SUMMIT-C-02). A prototype was designed to display landmarks during the preparation phase and Calot's triangle dissection. A prospective clinical feasibility study using the cross-AI system was performed in 20 LC cases. The primary endpoint of this study was the appropriateness of the detection timing of landmarks, which was assessed by an external evaluation committee (EEC). The secondary endpoint was the correctness of landmark detection and the contribution of cross-AI in preventing BDI, which were assessed based on the annotation and 4-point rubric questionnaire. Cross-AI-detected landmarks in 92% of the phases where the EEC considered landmarks necessary. In the questionnaire, each landmark detected by AI had high accuracy, especially the landmarks of the common bile duct and cystic duct, which were assessed at 3.78 and 3.67, respectively. In addition, the contribution to preventing BDI was relatively high at 3.65. The cross-AI system provided landmark detection at appropriate situations. The surgeons who previewed the model suggested that the landmark information provided by the cross-AI system may be effective in preventing BDI. Therefore, it is suggested that our system could help prevent BDI in practice. Trial registration University Hospital Medical Information Network Research Center Clinical Trial Registration System (UMIN000045731).

Restoration of Global Offset and Limb Length in Primary Unilateral Total Hip Arthroplasty When Preoperative Templating is not Applied

Background: Preoperative templating is an essential step before performing any total hip arthroplasty (THA). Restoration of global offset (GO) and limb length (LL) were among the templating purposes. Thus, we aimed to perform THA without preoperative templating based on clinical examination and intra-operative anatomical landmarks to restore hip biomechanics.Patients and Methods: This prospective observational study was conducted on 40 patients with primary THA through the posterior approach. The lesser trochanter was used to determine the level of femoral neck cut, the femoral component insertion depth, and version, along with adjusting the level of the center of the femoral head to the tip of the greater trochanter. The transverse acetabular ligament (TAL) was used as a reference for the acetabular component version and inclination. To optimize the LL, preoperative clinical assessment, intra-operative comparison with the normal side, soft tissue tension, and shuck test were used. GO was adjusted using the depth of acetabulum after reaming, placing the acetabular component fit or 10% overhang from the ridge and gluteus medius muscle tension. Postoperatively, computed tomography (CT) scan was used for measuring the GO (acetabular offset (AO) + femoral offset (FO)) and limb length discrepancy (LLD) and compared to the sound side. Pre and postoperatively, LL was measured using a tape measure from the anterior superior iliac spine (ASIS) to the medial malleolus.Results: Depending on postoperative CT measurements, there was no significant difference between the mean normal and operative GO (P=0.894). The mean LL difference between the two sides was 0.38 cm (P=0.007). Clinically, the mean LLD (comparing the normal side with the operated side preoperatively) was 1.001 cm, while the mean LLD was 0.722 cm (P=0.0455).Conclusions: This study demonstrated that when the preoperative templating step is omitted, depending on intraoperative landmarks, neither the GO nor the AO and FO of the operated side were significantly affected. The mean radiological and clinical postoperative LLD was almost consistent, and the mean difference was &lt; 1 cm, which is within the acceptable range. Do not use abbreviations in abstract and conclusions.

Application of Surface Landmarks Combined with Image-Guided Sinus Location in the Retrosigmoid Approach and Their Clinic-Image Relationship Analysis.

Objectives During craniotomy for cerebellopontine angle (CPA) lesions, the exact exposure of the margin of the venous sinuses complex remains an essential but risky part of the procedure. Here, we revealed the exact position of the asterion and sinus complex by combining preoperative image information and intraoperative cranial landmarks, and analyzed their clinic-image relationship. Methods Ninety-four patients who underwent removal of vestibular schwannoma (VS) through retrosigmoid craniotomies were enrolled in the series. To determine the exact location of the sigmoid sinus and the transverse sinus and sigmoid sinus junction (TSSJ), we used preoperative images, such as computed tomography (CT) and/or magnetic resonance imaging (MRI) combined with intraoperative anatomical landmarks. The distance between the asterion and the sigmoid sinus was measured using MRI T1 sequences with gadolinium and/or the CT bone window. Results In 94 cases of retrosigmoid craniotomies, the asterion lay an average of 12.71 mm on the posterior to the body surface projection to the TSSJ. Intraoperative cranial surface landmarks were used in combination with preoperative image information to identify the distance from the asterion to the sigmoid sinus at the transverse sinus level, allowing for an appropriate initial burr hole (the margin of the TSSJ). Conclusion By combining intraoperative anatomical landmarks and preoperative image information, the margin of the TSSJ, in particular, the inferior margin of the transverse sinus, can be well and thoroughly identified in the retrosigmoid approach.

Image-Free Robotic-Assisted Total Knee Arthroplasty Improves Implant Alignment Accuracy: A Cadaveric Study.

Improving resection accuracy and eliminating outliers in total knee arthroplasty (TKA) is important to improving patient outcomes regardless of alignment philosophy. Robotic-assisted surgical systems improve resection accuracy and reproducibility compared to conventional instrumentation. Some systems require preoperative imaging while others rely on intraoperative anatomic landmarks. We hypothesized that the alignment accuracy of a novel image-free robotic-assisted surgical system would be equivalent or better than conventional instrumentation with fewer outliers. Forty cadaveric specimens were used in this study. Five orthopedic surgeons performed 8 bilateral TKAs each, using the VELYS Robotic-Assisted System (DePuy Synthes) and conventional instrumentation on contralateral knees. Pre-resection and postresection computed tomography scans, along with optical scans of the implant positions were performed to quantify resection accuracies relative to the alignment targets recorded intraoperatively. The robotic-assisted cohort demonstrated smaller resection errors compared to conventional instrumentation in femoral coronal alignment (0.63° ± 0.50° vs 1.39° ± 0.95°, P < .001), femoral sagittal alignment (1.21° ± 0.90° vs 3.27° ± 2.51°, P < .001), and tibial coronal alignment (0.93° ± 0.72° vs 1.65° ± 1.29°, P= .001). All other resection angle accuracies were equivalent. Similar improvements were found in the femoral implant coronal alignment (0.89° ± 0.82° vs 1.42° ± 1.15°, P= .011), femoral implant sagittal alignment (1.51° ± 1.08° vs 2.49° ± 2.10°, P= .006), and tibial implant coronal alignment (1.31° ± 0.84° vs 2.03° ± 1.44°, P= .004). The robotic-assisted cohort had fewer outliers (errors >3°) for all angular resection alignments. This invitro study demonstrated that image-free robotic-assisted TKA can improve alignment accuracy compared to conventional instrumentation and reduce the incidence of outliers.

Application of aided three-dimension CT navigation system in craniocervical junction malformation disease surgery

To investigate the related problems of three-dimension CT navigation system applied to craniocervical junction malformation diseases surgery. The clinical data of 61 patients with craniocervical junction malformation disease who underwent surgical treatment from July 2015 to March 2018 was retrospectively analyzed. There were 39 males and 22 females aged from 25 to 73 years old with a mean of (46.20±12.09) years. According to the different ways of screw placements, these patients were divided into navigation group (30 cases) and non navigation group (31 cases). The screws insertion in the navigation group were guided under three-dimension CT computer-aided navigation system, while the screws insertion were guided by C-arm fluoroscopy and intraoperative anatomical landmarks in non-navigation group. All surgeries were performed by the same group of surgeons. All cases were scanned by CT after operation to assess the accuracy of the screw insertion. A total of 122 screws were inserted in the study, including 60 screws in navigation group and 62 screws in non-navigation group. The screw positions in navigation group were all satisfactory, and there were no screw-related complications. The position of 3 screws (4.83%) in non-navigation group was not satisfactory, and there was no obvious neurological symptoms after operation. The operation time of navigation group was from 87.5 to 112.5 min with a mean of (99.6± 12.0) min;and non-navigation group was from 87.5 to 107.5 min, with a mean of (97.5±10.5) min. There was no statistically significant difference in the operation time between two groups (P>0.05). The screw insertion time in navigation group was from 1.50 to 4.20 min, with a mean of (2.51±1.02) min;and non navigation group was from 1.80 to 5.10 min, with a mean of (3.25±1.05) min. The screw insertion time in navigation group was shorter than that in non-navigation group (P<0.05). The intraoperative blood loss in navigation group was from 122 to 153 ml, with a mean of (137.57±9.48) ml, which in non-navigation group wasfrom 121 to 158 ml, with a mean of (138.75±8.56) ml, there was no statistically significant difference between two groups (P>0.05). The three-dimensional CT computer-aided navigation system has the characteristics of clear imaging and accurate positioning, which can help improve the accuracy and safety of the screw insertion in craniocervical junction malformation disease surgery.

Orbital Bony Reconstruction With Presized and Precontoured Porous Polyethylene-Titanium Implants.

Complex bony orbital defects are reconstructively challenging due to loss of intraoperative anatomical landmarks and adjacent support. Presized and precontoured porous polyethylene-titanium implants (Medpor Titan 3D Orbital Floor Implant) are designed to reestablish normal orbital floor and medial wall anatomy and are modeled after anatomically averaged orbits. This is the first study to report clinical outcomes with this implant. This retrospective case series reviewed clinical data and outcomes for patients undergoing orbital reconstruction with a presized and precontoured porous polyethylene-titanium orbital implant from January 2016 to June 2018. A total of 34 orbits of 33 patients were identified (mean age: 43 ± 16 years, 70% men). Most bony defects were a result of trauma and included large orbital floor deformities (100%), medial wall defects (74%), disrupted inferomedial struts (68%), and broken posterior ledges (82%). Symptomatic diplopia (73%) and enophthalmos (89%, mean: 3.7 ± 2.1 mm) were common preoperatively. Many cases were revisions (44%). Mean follow up was 7.8 ± 6.7 months. All patients had improved globe positioning, enophthalmos, and hypoglobus. Seven patients had persistent postoperative diplopia: 6 responded to prism therapy and 1 required strabismus surgery. One patient required retrobulbar hematoma drainage and 1 patient required implant explantation due to chronic infection. Commercially available presized and precon toured porous polyethylene-titanium implants are useful for complex orbital bony defects and can achieve functional improve ments in diplopia, enophthalmos, and extraocular motility with a low incidence of postoperative complications or revisional surgery.

Brainstem navigation with Intraoperative anatomical landmarks registration: Technical note

Background. Cranial navigation in brainstem surgery can be especially challenging due to registration method limitation and complex anatomic orientation. Surface anatomical landmarks are not available and fiducial registration usually needs image acquisition at the day of surgery. Intraoperative registration is often used during spinal navigation with safe and reliable accuracy. We present our technique of navigation for brainstem lesions surgeries using intraoperative anatomical landmarks for registration. Methods. From March 2008 to November 2018, 38 patients underwent suboccipital midline approaches for removal of brainstem and/or fourth ventricle lesions with frameless navigation. We performed CT scan and MRI sequence with gadolinium enhancement for each patient a day before the operation. The CT/MRI image fusion and surgical planning was performed in Brainlab® workstation. Navigation registration was performed after skin incision and external skull base anatomical landmarks exposure. Results. The anatomical landmarks used for registration was based on bone structures visible on CT images. The accuracy flaw was insignificant for brainstem navigation, especially for the roof and lateral limits of the fourth ventricle. The image-guided system was very useful for tumor localization and removal in all cases. Conclusions. Intraoperative anatomical landmarks registration is a fast and safe method for brainstem navigation. The brainstem is a fixed encephalic structure and the shifting is insignificant. Anatomical landmarks (inion, foramen magnum, nucal lines, C1 posterior arc) and a careful surgical planning are necessary in order to avoid accuracy lost.

Relationship of Intraoperative Anatomical Landmarks, the Scapular Plane and the Perpendicular Plane with Glenoid for Central Guide Insertion during Shoulder Arthroplasty.

BackgroundThis study was undertaken to evaluate the positional relationship between planes of the glenoid component (the scapular plane and the perpendicular plane to the glenoid) and its surrounding structures.MethodsComputed tomography (CT) images of both shoulders of 100 patients were evaluated using the 3-dimensional CT reconstruction program (Aquarius®; TeraRecon). We determined the most lateral scapular bony structure of the scapular plane and measured the shortest distance between the anterolateral corner of the acromion and the scapular plane. The distance between the scapular plane and the midpoint of the line connecting the posterolateral corner of acromion and the anterior tip of the coracoid process (fulcrum axis) was also evaluated. The perpendicular plane was then adjusted to the glenoid and the same values were re-assessed.ResultsThe acromion was the most lateral scapular structure of scapular plane and perpendicular plane to the glenoid. The average distance from the anterolateral corner of the acromion to the scapular plane was 10.44 ± 5.11 mm, and to the plane perpendicular to the glenoid was 9.55 ± 5.13 mm. The midpoint of fulcrum axis was positioned towards the acromion and was measured at 3.90 ± 3.21 mm from the scapular plane and at 3.84 ± 3.17 mm from the perpendicular plane to the glenoid.ConclusionsOur data indicates that the relationship between the perpendicular plane to the glenoid plane and its surrounding structures is reliable and can be used as guidelines during glenoid component insertion (level of evidence: Level IV, case series, treatment study).

Skull anatomical landmarks combine CT reconstruction via assisted retrosigmoid sinus approach for craniotomy

Objective To investigate the cranial fossa skull anatomical landmarks combining CT reconstruction via assisted retrosigmoid sinus approach for craniotomy. Methods Twenty patients operated via retrosigmoid sinus approach at the Department of Neurosurgery, Nanjing Brain Hospital Affiliated to Nanjing Medical University from December 2014 to May 2014 were enrolled respectively. before operation, 3-D CT reconstruction software was used to reconstruct posterior fossa 3-D skulls of the patients, and a virtualkeyhole was made on the position of the groove of transverse sinusinner of the inner surface of skull and the sigmoid sinus sulcus transitional position within the lower edge, and then with the aid of the anatomical landmarks such as star points and vertices of digastric groove, thekeyhole was located, obtaining the distance and angle information, making paper models according to this information. After model disinfection, it is relative to the intraoperative anatomic landmarks, and thekeyhole was located. Results No venous sinus rupture and hemorrhage occurred in 20 patients. The transverse sinus and sigmoid sinus transitional areas within thekeyhole were exposed clearly in 15 patients; while those were not the same case in 5 patients. They were exposed after the bone was ground or bitten away (4.0±0.3 mm) from the front outer direction. The center distance of star point-keyhole was 6.8-21.6 mm (mean 14.0±3.6 mm). The angle between the connecting line of the star point-center and baseline was 4-50° (mean 24±13°). Conclusions Using posterior cranial fossa skull surface landmarks combine with the location of 3-D CT bone reconstruction is more accurate. The risk of venous sinus injury is low. It may realize individualized localization ofkeyhole . Key words: Imaging, three-dimensional; Skull; Anatomic landmarks; Keyhole; Surgical technique

70. Intraoperative anatomical landmarks for identification of the recurrent laryngeal nerve during thyroidectomy: A meta-analysis

70. Intraoperative anatomical landmarks for identification of the recurrent laryngeal nerve during thyroidectomy: A meta-analysis

Технические аспекты модифицированной тотальной экстраперитонеоскопической герниопластики у больных с паховой грыжей

A number of technical shortcomings has been revealed recently despite huge inguinal hernias treatment progress according to numerous studies in modern herniology. The problem of surgical treatment results improving is considered to be a part of technical aspects issue in which videoendoscopic TEP-repair is extremely important. Aim. Our goal was to improve surgical treatment results of inguinal hernia repairs by modifying totally extraperitoneal hernia repair. Methods and results. 67 patients underwent modified totally extraperitoneal hernia repair. In every patient we used meticulous step by step dissection of the extraperitoneal space which substitutes dangerous and expensive balloon dilation and prevents from excessive extraperitoneal space sack formation and bleeding. Intraoperative anatomic landmarks and hernia defect measurements specify and individualise a mesh size and help to avoid any torsion and migration of the mesh and subsequent rough scar and chronic pain formation. We used inguinal bandage postoperatively for early mesh shift prevention. Conclusion. No hernia recurrence, low complication rate and good life quality in postoperative period after modified TEP-repair proved its high efficacy and superiority.

MP58-03 INTRAOPERATIVE OPTICAL BIOPSY DURING ROBOTIC-ASSISTED RADICAL PROSTATECTOMY USING CONFOCAL LASER ENDOMICROSCOPY: INITIAL FEASIBILITY STUDY

You have accessJournal of UrologyProstate Cancer: Localized VI1 Apr 2014MP58-03 INTRAOPERATIVE OPTICAL BIOPSY DURING ROBOTIC-ASSISTED RADICAL PROSTATECTOMY USING CONFOCAL LASER ENDOMICROSCOPY: INITIAL FEASIBILITY STUDY Aristeo Lopez, Daniel Bui, Jen-Jane Liu, Kathleen Mach, Theodore Harris, Robert Rouse, John Leppert, and Joseph Liao Aristeo LopezAristeo Lopez More articles by this author , Daniel BuiDaniel Bui More articles by this author , Jen-Jane LiuJen-Jane Liu More articles by this author , Kathleen MachKathleen Mach More articles by this author , Theodore HarrisTheodore Harris More articles by this author , Robert RouseRobert Rouse More articles by this author , John LeppertJohn Leppert More articles by this author , and Joseph LiaoJoseph Liao More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2014.02.1819AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Of significant technical challenge to radical prostatectomy is the prostate’s deep pelvic location and close proximity to the urinary sphincter and neurovascular bundles. Advancements in intraoperative image guidance may improve functional and oncologic outcomes of RARP. Confocal laser endomicroscopy (CLE) is an emerging technology that provides dynamic in vivo imaging of tissue with micron-scale resolution with images comparable to standard histology. In this study, we report the initial feasibility of intraoperative optical biopsy using CLE during RARP. METHODS With IRB approval, ten patients scheduled for RARP were recruited. Probe-based CLE was performed with the Cellvizio® system (Mauna Kea Technologies) using either a 0.85-mm or 2.6-mm probe inserted through the standard laparoscopic port. Intravenous fluorescein (10%) was used as the optical contrast agent. Standard robotic instruments were used to grasp and direct the probe for image acquisition. TilePro™ functionality (Intuitive Surgical) was used to integrate 3D-view of the operative field with confocal imaging. RESULTS Intraoperative microscopy was performed in 10 patients. CLE was safely performed in all the patients with no intraoperative complications related to CLE. Intraoperative anatomic landmarks that were imaged and characterized include prostatic capsule, NVB, bladder neck, urinary sphincter, and other periprostatic structures. The NVB was imaged in situ within the lateral prostatic fascia and after the nerve-sparing procedure. Successful nerve sparing is characterized by presence of moving red blood cells within the capillaries and intact linear structures consistent with nerve fibers. CONCLUSIONS We report the initial feasibility and safety of intraoperative optical biopsy during RARP. Image guidance and tissue interrogation using CLE may improve functional and oncologic outcomes related to RARP. © 2014FiguresReferencesRelatedDetails Volume 191Issue 4SApril 2014Page: e659 Advertisement Copyright & Permissions© 2014MetricsAuthor Information Aristeo Lopez More articles by this author Daniel Bui More articles by this author Jen-Jane Liu More articles by this author Kathleen Mach More articles by this author Theodore Harris More articles by this author Robert Rouse More articles by this author John Leppert More articles by this author Joseph Liao More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Intraoperative Anatomic Landmarks for Resection of the Amygdala during Medial Temporal Lobe Surgery

To establish reliable gross landmarks for resecting the amygdala intraoperatively, especially during anteromedial temporal lobectomy and amygdalohippocampectomy for epilepsy surgery. Reliable landmarks would allow its safe and complete resection as well as its potential en bloc removal for detailed electrophysiological and histopathological analyses. Ten adult cadavers (20 sides) were used. Two adjacent anatomic structures were identified: the bifurcation of the middle cerebral artery (MCA point) and the entry point of the anterior choroidal artery (AChoA) at the anterior origin of the choroid plexus into the temporal horn (inferior choroidal point referred to as the AChoA point). Following removal of the brain tissue inferior and anterior to the imaginary line connecting these 2 anatomic landmarks, cross sectional histopathological analysis of the remaining temporal and frontal lobes was performed to verify the presence or absence of any nervous tissue belonging to the amygdala complex. In all 20 sides, the entire amygdala complex was found anterior and inferior to the transection made along the MCA-AChoA line. No apparent injury to the adjacent striatum was discovered. Two easily identifiable points, including the middle cerebral artery bifurcation and the inferior choroidal point, may define a line that reliably disconnects the amygdala complex from the remaining temporal and frontal lobes. These landmarks may assist in resection of the amygdale while preserving important adjacent structures, including the striatum.

Transsphenoidal hypophysectomy for treatment of pituitary-dependent hyperadrenocorticism in 7 cats.

Evaluation of microsurgical transsphenoidal hypophysectomy for the treatment of pituitary-dependent hyperadrenocorticism (PDH) in cats. Prospective clinical study. Seven cats with PDH. Urinary cortisol/creatinine ratios, pituitary-adrenocortical function tests, and computed tomography (CT) were performed on 7 cats that presented with a provisional diagnosis of hyperadrenocorticism. All cats underwent microsurgical transsphenoidal hypophysectomy with histologic examination of the excised specimen. Follow-up consisted of clinical evaluation, repeat adrenocortical function testing, and CT. Four cats had concurrent diabetes mellitus. In all cats, the urinary cortisol/creatinine (C/C) ratios were elevated. The dexamethasone screening test showed that 2 cats did not meet the criterion for hyperadrenocorticism. The response of the cats' plasma concentrations of cortisol and adrenocorticotrophic hormone to a high dose of dexamethasone varied from very sensitive to completely dexamethasone resistant. Basal plasma alpha-melanocyte-stimulating hormone concentrations were elevated in 2 cats with a pars intermedia adenoma and in 3 cats with an adenoma that originated from the anterior lobe. Preoperative CT enabled accurate assessment of pituitary size (5 nonenlarged pituitaries with a height <4 mm and 2 enlarged pituitaries with a height >5 mm) and localization relative to intraoperative anatomic landmarks. Two cats died within 4 weeks after surgery of a nonrelated disease. In the remaining 5 cats, the hyperadrenocorticism went into both clinical and biochemical remission. Hyperadrenocorticism recurred in 1 cat after 19 months, but no other therapy was given and the cat died at home 28 months after surgery. CT evaluation of this cat had identified pituitary remnants 6 weeks after surgery. The main postoperative complications were oronasal fistula (1 cat), complete dehiscence of the soft palate (1 cat), and transient reduction of tear production (1 cat). One cat died at 6 months (undefined anemia), and another cat at 8 months (recurrent nose and middle ear infection secondary to soft palate dehiscence) after surgery. In the surviving 2 cats, the remission periods at the time of writing were 46 and 15 months. In the 2 cats with sufficient follow-up time, the concurrent diabetes mellitus disappeared, ie, insulin treatment could be discontinued at 4 weeks and 5 months after hypophysectomy. In all 7 cats, the histologic diagnosis was pituitary adenoma. Microsurgical transsphenoidal hypophysectomy is an effective method of treatment for feline PDH in specialized veterinary institutions having access to advanced pituitary imaging techniques. Concurrent diabetes mellitus is usually reversible after hypophysectomy. Thorough presurgical screening for coexisting diseases is imperative. PDH in cats can be effectively treated by hypophysectomy. The neurosurgeon performing hypophysectomy must master a learning curve and must be familiar with the most frequent complications of the operation to treat them immediately and effectively. Urinary C/C ratios are sensitive indicators for the assessment of remission and recurrence of hyperadrenocorticism.

Are Anatomic Landmarks Reliable in Determination of Fusion Level in Posterolateral Lumbar Fusion?

Determination of the fusion level by direct observation and palpation of anatomic landmarks is compared with the finding obtained from a lateral intraoperative radiograph. To assess the reliability of the use of intraoperative anatomic landmarks in determination of the fusion level. Accurate determination of the level to be fused in noninstrumented posterolateral fusion is crucial. No studies are available in which the value of direct observation and palpation of the anatomic landmarks in determination of the fusion level has been assessed. Eighty patients who underwent posterolateral fusion without instrumentation in the lumbosacral spine were included in this study. During surgery, first, the cephalad transverse process at the desired level to be fused was determined by direct observation and palpation of the anatomic landmarks; second, a metal mark was placed beneath the cephalad transverse process at the level determined by anatomic landmarks. This was followed by a lateral radiograph. The consistency and discrepancy between the use of the anatomic landmarks and lateral radiography in determining the desired fusion level were recorded. The fusion level determined by direct observation and palpation of the anatomic landmarks was accurate in 76 (95%) cases. In the remaining four cases, intraoperative x-rays determined that the selection of the cephalad transverse process for fusion was one level too high in three cases and one level too low in the other case. All errors in determination of the level to be fused occurred in patients who had extensive laminectomy at L4-S1. Determination of fusion level by direct observation and palpation of the anatomic landmarks is not reliable in patients who have had or require decompressive procedures. A lateral radiograph should be routinely obtained for accurate identification of the level to be fused.

Results of transsphenoidal hypophysectomy in 52 dogs with pituitary-dependent hyperadrenocorticism.

To evaluate microsurgical transsphenoidal hypophysectomy in dogs with pituitary-dependent hyperadrenocorticism (PDH). Prospective study to evaluate the results (survival and disease-free interval, remission, recurrence) and complications of microsurgical transsphenoidal hypophysectomy by clinical follow-up, computed tomography (CT), and urinary corticoid-to-creatinine (C/C) ratios in dogs with PDH. The effect of surgical experience was investigated by comparing results of hypophysectomy cases 1 through 26 and 27 through 52. 52 dogs with PDH. Preoperative CT enabled accurate assessment of pituitary size (24 nonenlarged and 28 enlarged) and localization relative to intraoperative anatomic landmarks. Treatment failures included procedure-related mortalities (five dogs) and incomplete hypophysectomies (four dogs). The 1-year estimated survival rate was 84% (95% confidence interval [CI], 71% to 92%). The 2-year estimated survival rate was 80% (95% CI, 65% to 90%). In 43 dogs, the hyperadrenocorticism went into remission. Hyperadrenocorticism recurred in five dogs. The 1-year estimated relapse-free fraction was 92% (95% CI, 76% to 97%). The main complications were transient, mild, postoperative hypernatremia; transient reduction or cessation of tear production (25 eyes in 18 dogs); permanent (five dogs) or prolonged (nine dogs) diabetes insipidus; and secondary hypothyroidism. Normal tear production had resumed in all but one case after a median period of 10 weeks. In the second case series (27 through 52), the hospitalization period was shorter, the number of dry eyes fewer, the survival fraction greater, and the postoperative mortality lower than in the first series. In 15 dogs in which remission was obtained, postoperative CT images suggested the presence of small pituitary remnants; in 1 of these, hyperadrenocorticism recurred. In 46 dogs, the histological diagnosis was pituitary adenoma. Microsurgical transsphenoidal hypophysectomy in dogs with PDH is an effective method of treatment in specialized veterinary institutions having access to advanced pituitary imaging techniques. Postoperative CT findings do not correlate well with remission or subsequent recurrence of hyperadrenocorticism. The neurosurgeon performing hypophysectomies must master a learning curve and must be familiar with the most frequent complications of the operation to recognize them as early as possible and to treat them immediately and effectively. Urinary C/C ratios are sensitive indicators for the assessment of remission and recurrence of hyperadrenocorticism.

Microsurgical Anatomy for Lateral Approaches to the Foramen Magnum with Special Reference to Transcondylar Fossa (Supracondylar Transjugular Tubercle) Approach

Microsurgical anatomy for lateral approaches to the foramen magnum, especially for transcondylar fossa (supracondylar transjugular tubercle) approach, was studied using cadavers. The transcondylar fossa approach is an approach in which extradural removal of the posterior portion of the jugular tubercle through the condylar fossa is added to the far lateral approach. Some differences between this approach and the transcondylar approach are demonstrated. The atlanto-occipital joint and the jugular tubercle are obstacles for the lateral approaches. The condylar fossa forming the external occipital surface of the jugular tubercle is located supero-posterior to the occipital condyle. The fossa is limited laterally by the sigmoid sulcus and the jugular foramen. The posterior condylar canal communicating anteriorly with the distal end of the sigmoid sulcus, the jugular foramen, or the hypoglossal canal opens at the bottom of the fossa. The condyle is situated inferior to the posterior condylar and hypoglossal canals, and the jugular tubercle is located superior to them. In the transcondylar fossa approach the posterior part of the jugular tubercle is extradurally removed, but the condyle and the atlanto-occipital joint are untouched. On the other band, in the transcondylar approach the medial parts of the condyle and the lateral mass of Cl are removed. The latter approach offers better visualization of the inferior part of the foramen magnum. The essential difference of the two approaches is in the direction of looking and the extent of resection of the atlanto-occipital joint. Both approaches offer excellent view of the ventral dural space in the lower clivus and the foramen magnum, but the level of exposure differs somewhat between them. In the lateral approaches to the foramen magnum, the condylar fossa, the posterior condylar canal, and the posterior condylar emissary vein all play an important role as intraoperative anatomical landmarks.