Operative Nuances of Capsular Dissection Techniques and Capsule Morphology in Pituitary Adenomas: Past 1-Year Case Experiences of a Tertiary Center.

BACKGROUND AND OBJECTIVES: The widespread use of endoscope and increased surgical experiences in pituitary adenomas (PAs) has raised the expectations for higher resection and cure rates. The subject that will meet this expectation in all types of adenomas is the capsule and its dissection. The purpose of this study was to go beyond the commonly mentioned pseudocapsule definition for small-sized adenomas in previous studies and to describe the capsule structure in different morphologies present in pituitary adenomas of all sizes. This includes detailing the nuances of capsular dissection (CD) and presenting postoperative surgical outcomes through the experiences of a high-volume tertiary center. METHODS: In our center, 534 patients underwent endoscopic trans-sphenoidal surgery because of pituitary adenoma in 2022 by the same surgeon. The data of the patients were examined retrospectively. The surgical techniques applied were grouped as adenoma resection only, capsular resection after internal debulking, and direct extracapsular resection. RESULTS: CD was performed in 275 (51.5%) patients. The gross total resection (GTR) rate in nonsecretory adenomas with and without CD was 90.7% (97/107) and 90.7% (97/107), respectively. The remission rate in secretory adenomas with and without CD was 81.0% (136/168) and 44.0% (67/152), respectively. When the patients were examined in 2 groups as those who underwent CD and those who did not, the application of CD had a positive predictive value in terms of GTR/remission (P: .036). Capsule thickness was not found to be statistically significant depending on tumor subtype, size, and aggressiveness, but capsule thickness was statistically significant in terms of total capsular resection (P: .045). CONCLUSION: The morphology of the capsule, tumor size/subtype/consistency, and patient-specific factors are crucial for the selection of the surgical technique to be applied. It is possible to increase the GTR/remission rates in adenomas of all sizes by capsule dissection. Moreover, performing CD does not contribute significantly to the development of potential complications in such cases.

Clinical and therapeutic outcomes of pediatric pituitary adenomas: a single pituitary center experience.

PURPOSE: Pediatric pituitary adenomas (PPA) are rare. Although PPAs are mostly benign, they can be challenging to manage. Most studies evaluating PPA are based on surgical series. We aimed to present the clinical features, hormonal status and treatment outcomes of children with PPA managed in a joint neuroendocrine setting. METHODS: In this single-center study, demographic, clinical and endocrinological data of patients under 19 years old who were followed up with the diagnosis of PPA between 2002-2022 were retrospectively reviewed. A total of 21 studies published in the past 20 years were also systematically reviewed. RESULTS: There were 79 patients (52 girls, 27 boys) with a median age of 15.8 years. Median follow-up time was 30 months. The most common adenoma subtype was non-functioning adenoma (NFA) (35.5%), followed by prolactinoma (29.1%), corticotropinoma (21.5%), and somatotropinoma (13.9%), respectively. The frequency of micro and macroadenomas was almost equal while 38% of all adenomas were invasive. Headache, visual impairment and menstrual irregularity were the most common complaints, while the most common hormonal deficiency at diagnosis was central hypothyroidism (31.6%), followed by hypogonadotropic hypogonadism (22.7%), growth hormone deficiency (15.2%) and central adrenal insufficiency (11.4%), respectively. Fifty patients (63.2%) underwent endoscopic endonasal transsphenoidal surgery (EETS). Following the surgery, impaired endocrine functions recovered at a rate of 62% while permanent central diabetes insipidus was observed in 6%, and new onset hypopituitarism developed in 4%. CONCLUSION: NFA was more common in this cohort than in previous reports, which is one of the largest PPA series in the literature. Hormonal disorders, which were common at the time of diagnosis, were largely resolved with appropriate endocrinological and surgical approaches, while the rate of pituitary hormonal deficiencies after EETS was relatively low. Therefore, we recommend that children with PPA be managed in the setting of a high-volume pituitary center to provide long-term low morbidity.

Surgical outcomes and follow-up results of 53 pediatric craniopharyngioma cases: a single-center study.

OBJECTIVE: Craniopharyngiomas are locally invasive neoplasms, and they cause potential lifelong morbidity because of their tendency for local recurrence. Despite advancements in endoscopic techniques, gross-total resection (GTR) of tumors with invasion or adhesion to important surrounding anatomical structures is extremely difficult. The authors present a single-center study that evaluated the impact of the endoscopic endonasal approach (EEA) on the surgical outcomes of pediatric craniopharyngiomas, the factors affecting the resection rate, and recurrence. METHODS: A total of 44 pediatric patients (age ≤ 18 years) who were treated via the EEA for craniopharyngioma from August 1997 to June 2022, as well as their 53 operations, were included in this study. The preoperative radiological configuration and surgical data of these cases were assessed. Also, preoperative and postoperative clinical (endocrinologic, neurological, and ophthalmological), hypothalamic, physical and social development, and neurocognitive assessment data were described. RESULTS: In total, 37 cases (69.8%) had no history of operation beforehand. The most common symptoms at presentation were endocrine disturbances (98.1%), headache without vomiting (84.3%), and visual disturbance (51%). Cases were classified as infrasellar (1.9%), sellar (32.1%), sellar-suprasellar (52.8%), and suprasellar (13.2%) localization. GTR was achieved in 34/53 cases (64.1%). The rate of GTR was higher in infrasellar and sellar tumors compared with sellar-suprasellar and suprasellar tumors (p = 0.003), and preoperative hypothalamic involvement was associated with lower likelihood of GTR (p = 0.024). Moreover, with experience, the rate of GTR increased (p = 0.037). Postoperative complications, other than endocrine impairment, occurred in 10/53 cases (18.9%). The mean duration of follow-up was 53.57 months. At follow-up, 21/53 (39.6%) cases presented with tumor recurrence. The 5-year progression-free survival (PFS) rate was 48.5%. There was a statistically significant difference between the GTR and other-than-GTR groups in terms of PFS (p < 0.001). According to univariate analysis, smaller tumor (p = 0.017), infrasellar and sellar localization (p = 0.031), and GTR (p < 0.001) were significantly associated with decreased rate of recurrence. Also, there was a statistically significant association between the recurrence rate and adhesion strength of the tumor (p < 0.001). CONCLUSIONS: This retrospective cohort study revealed surgical indications for EEA, as well as factors affecting the resection rate, recurrence, and quality of life during the follow-up period of the included cases. The authors believe that GTR should be the goal for craniopharyngioma treatment, but the authors' treatment approach was to provide a balance between radical surgery with maximum safety and adjuvant treatment for long-term disease control.

Retinal vascular and structural recovery analysis by optical coherence tomography angiography after endoscopic decompression in sellar/parasellar tumors.

We assessed the potential retinal microcirculation alterations for postoperative visual recovery in sellar/paraseller tumor patients with Optical Coherence Tomography Angiography (OCT-A). Two hundred ten eyes with sellar/parasellar tumor for which preoperative and postoperative (3 months) MRI Scans, Visual Acuity Test, Optical Coherence Tomography (OCT), OCT-A and, Visual Field Test data were available, besides 92 healthy eyes were evaluated. In the preoperative phase, significant reductions were observed in retinal vascular densities in various regions, including the Superficial Retinal Capillary Plexus (SRCP) (whole: p < 0.001, fovea: p = 0.025, parafovea: p < 0.001), Deep Retinal Capillary Plexus (DRCP) (whole: p < 0.001, fovea: p = 0.003, parafovea: p < 0.001), Peripapillary Vascular Density (PVD) (whole: p = 0.045, peripapillary: p < 0.001, nasal: p < 0.001, inferior: p < 0.001, temporal: p < 0.001), and Retinal Nerve Fiber Layer (RNFL) (nasal: p = 0.024, inferior: p < 0.001, temporal: p < 0.001, superior: p < 0.001) compared to the healthy control group. After surgery, the postoperative data of patients without chiasmal distortion were compared to their preoperative data. In the postoperative evaluation, significant increases were observed in vascular densities in patients without chiasmal distortion in the SRCP (whole: p < 0.001, parafovea: p = 0.045), DRCP (whole: p = 0.007, fovea: p = 0.006, parafovea: p = 0.040), PVD (peripapillary: p = 0.010, inferior: p < 0.001, temporal: p < 0.001, superior: p < 0.001), and RNFL (nasal: p = 0.011, inferior: p = 0.034, temporal: p = 0.046, superior: p = 0.011). Furthermore, significant associations were observed in the ROC analysis between the postoperative Visual Field Mean Deviation (VFMD) and SRCP (whole AUC = 0.793, p < 0.001, cut-off = 51.45, parafovea AUC = 0.820, p < 0.001, cut-off = 53.95), DRCP (whole AUC = 0.818, p < 0.001, cut-off = 55.95, parafovea AUC = 0.820, p < 0.001, cut-off = 59.05), PVD (temporal AUC = 0.692, p < 0.001, cut-off = 55.10), and RNFL (whole AUC = 0.690, p = 0.001, cut-off = 119.5, inferior AUC = 0.712, p < 0.001, cut-off = 144.75). These findings indicate a potential role of pre and post-operative OCT-A measurements in the assessment of surgical timing and postoperative visual recovery in patients with or without optic chiasm distortion.

Outcomes of Endoscopic Transsphenoidal Approach for More Aggressive Pediatric Pituitary Adenomas: Early- and Late-Term Results from a Single Center Experience.

OBJECTIVE: Pediatric pituitary adenomas are rare lesions and account for approximately 3% of all supratentorial tumors in children. There is a paucity of reports on endoscopic transsphenoidal surgery in children. The aim of this study was to assess the early/late outcomes of endoscopic pediatric pituitary adenoma surgery at a high-volume tertiary center, as well as to characterize the factors associated with aggressive growth, including the histopathological features. METHODS: Between August 1997 and June 2022, a total of 3256 patients underwent endoscopic transsphenoidal surgery for pituitary adenoma at the Department of Neurosurgery and Pituitary Research Center of the Kocaeli University School of Medicine. Of these, 70 (2.1%) pediatric patients (25 males, 45 females) (age ≤18 years) with a pathological diagnosis of pituitary adenoma were retrospectively reviewed. RESULTS: The mean age of patients was 15.5 ± 2.3 years. Among the hormone-secreting adenomas, 19 (34.5%) were adrenocorticotrophic hormone secreting, 13 (23.6%) were growth hormone secreting, 19 (34.5%) were prolactin secreting, and 4 (7.2%) were both growth hormone-prolactin secreting. Gross total resection was achieved in 93.3% of nonfunctional tumors. The early/late surgical remission rates for hormone-secreting adenomas were 61.5%/46.1% (mean follow-up: 63.7 ± 49.3 months) for acromegaly, 78.9%/68.4% (47.8 ± 51.0 months) for Cushing disease, 57.8%/31.5% (72.2 ± 59.5 months) for prolactinoma, and 25%/25% (35.2 ± 31.4 months) for growth hormone-prolactin-secreting adenomas. Five sparsely granulated corticotroph tumors, 5 sparsely granulated somatotroph tumors, and 11 densely granulated lactotroph tumors were classified as aggressive histopathological subtypes. CONCLUSIONS: The unique characteristics of the pediatric population and the aggressiveness of the disease in this population pose considerable therapeutic challenges. To increase treatment success, current adjuvant therapies that are appropriate for the morphological and biological characteristics of the tumor are required in addition to surgical treatment.

Investigation of Demyelination and Remyelination Processes of the Compressed Optic Chiasm: An Experimental Model.

AIM: To demonstrated demyelination and remyelination of the optic nerve histologically by electron microscopy in an experimental model similar to the compression of pituitary adenomas on the optic chiasm. MATERIAL AND METHODS: The rats were fixed to a stereotaxic device under deep anesthesia, and a balloon catheter was placed under the optic chiasm through a burr hole which was in front of the bregma in accordance with the brain atlas of rats. The animals were divided into five groups (n=8): control, mild compression demyelination, severe compression demyelination, mild compression remyelination, severe compression remyelination. The fine structures of the tissues obtained were evaluated using electron microscopy. RESULTS: We found a significant difference in the severity of degeneration when comparing group 1 with group 5 (p < 0.001); there was no degeneration in group 1 rats and severe degeneration in all of the group 5 rats. Oligodendrocytes were found in all rats in group 1 and none of the rats in no group 2. The nuclei were preserved in the group 1 rats but damaged in all of the group 5 rats. There were no lymphocytes or erythrocytes in group 1 and all positives in group 5. CONCLUSION: This technique, which induced degeneration without causing damage to the optic nerve with toxic or chemical agents, revealed Wallerian degeneration similar to tumoral compression. After compression relief, the optic nerve remyelination process can be better understood, particularly for sellar lesions. In our opinion, this model may guide future experiments to identify protocols to induce and accelerate remyelination.

Endoscopic Endonasal Approach Limitations and Evolutions for Tuberculum Sellae Meningiomas: Data from Single-Center Experience of Sixty Patients.

AIM: To determine the limits, to show the effect of tumor consistency on resection rates and to present the sinonasal morbidity rate in patients with tuberculum sellae meningiomas who underwent endoscopic endonasal approach. MATERIAL AND METHODS: We reviewed the medical data, radiological images, and surgical videos of the patients with pathologically confirmed meningiomas originating from the tuberculum sellae and they were operated via endoscopic endonasal approach between August 1997 and December 2020. We used our endoscopic classification based on infrachiasmatic corridor. In this classification, tumors were divided into those within the infrachiasmatic corridor and proximity of the optic nerve, internal carotid artery, and anterior artery complex and those outside the infrachiasmatic corridor. RESULTS: Gross total resection was achieved in 45/60 (75%) patients. We found that tumor consistency was statistically significant on resection rates. Simultaneously, tumor median diameters on the anteroposterior (≤21.15 mm), transverse (≤19.75 mm), and superoinferior (≤15 mm) axes were statistically significant on resection rates. CONCLUSION: In summary, the most important factor in selecting the surgical technique is the tumor size. Infrachiasmatic corridor boundaries are the limitations of endoscopic approach. These limitations can change based on surgeon's experience. Also, tumor consistency is a factor that affecting degree of tumor resection rates.

Endoscopic Transnasal Approach for Microprolactinomas with Experience of 105 Cases in a Single Center: Paradigmal Shift for Conventional Medical Therapy.

OBJECTIVE: The classically recommended first-line therapy for microprolactinomas is medical therapy. In the presence of drug resistance and intolerance after the use of dopamine agonists or when the patients prefer surgery instead of medication, surgical treatment is considered as second-line treatment. The high hormonal remission and low complication rates after surgery for microprolactinomas suggest that the surgical outcome of endoscopic surgeries may be better than medical therapy in well-selected patients. This study reports a large series of patients with microprolactinoma treated by endoscopic transnasal approach and evaluates the efficiency of surgical treatment. METHODS: Our study is a retrospective cohort analysis of patients with microprolactinoma operated on by an endoscopic transnasal approach between August 1997 and February 2022 by an experienced pituitary surgeon in a single tertiary center. Inclusion criteria for microprolactinoma were based on increased prolactin levels, microadenoma (<10 mm in diameter) on pituitary magnetic resonance imaging, and histopathologically verified lactotroph adenoma. RESULTS: The mean follow-up was 74.90 months (range, 6-207). The postoperative day 1 remission rate was 85.7% and the long-term remission rate was 74.3%. The long-term remission rates of the patients in the preference group were significantly higher than those of the patients in the resistant or intolerance group (P = 0.002). Patients who used dopamine agonists for more than 3 years had a lower remission rate compared with patients who used dopamine agonists for a shorter period or who did not use it (P = 0.01). The surgical complication rate was 4.76%. CONCLUSIONS: According to our findings, endoscopic transnasal surgery performed by an experienced neurosurgeon in well-selected patients with microprolactinoma can be offered with cure rates superior to medical therapy and may be an alternative first-line treatment option to dopamine agonists.

Endoscopic Transorbital Approach to the Cavernous Sinus Lateral Compartment (Anatomical Cadaver Study).

AIM: To determine whether the endoscopic transorbital (ETO) approach could be an alternative and a safer route to access the cavernous sinus (CS) lateral compartment. MATERIAL AND METHODS: ETO technique was studied on 3 cadavers and 6 CSes of these cadavers. Endoscopic dissection was visualized with a 0-degree angle endoscope and recorded with fiberoptic cable, light source and camera system and digital video recording system. RESULTS: Superior orbital fissure (SOF), optic canal (OC), anterior ethmoidal artery (AEA) and posterior ethmoidal artery (PEA) foramens were visualized with periorbital dissection. Anterior wall of CS was reached after drilling the optic strut (OS). When the wall was opened, CS lateral and anteroinferior compartments were visualized. Internal carotid artery (ICA) were visualized from proximal ring to the last 2 cm of paraclival carotid artery. Cranial nerves (CNs) within the CS and the course of the interclinoid ligament were revealed. CONCLUSION: The transorbital endoscopic method is an alternative approach to other techniques for accessing the lateral and anteroinferior compartments of CS. The advantages, disadvantages and limitations of the technique have been determined.

Operative nuances and surgical limits of the endoscopic approach to clival chordomas and chondrosarcomas: A single-center experience of 72 patients.

OBJECTIVE: Gross total resection (GTR) is the mainstay therapy for chordomas and chondrosarcomas to have the best prognosis. The aims of this study were to specify the limits of EEA, emphasize the need for additional combined approaches for tumors beyond these limitations for high resection rates, discuss the prognostic factors and operative nuances that affect GTR, and present the causes and characteristics of early and late recurrences. METHODS: We retrospectively analyzed the endoscopic endonasal surgeries in the Pituitary Research Center and Neurosurgery Department of the Kocaeli University Faculty of Medicine, Turkey between January 2004 and December 2019. We retrospectively reviewed the medical data, radiological images, and surgical videos of patients, and 72 patients with chordoma and chondrosarcoma were included in the study. RESULTS: Based on pathology reports, 72 patients (seven pediatric) were identified, to whom 91 endoscopic operations were performed. We determined the surgical limitations for each clival segment as superior, middle, and inferior. Then, we divided these into three subgroups according to whether the tumor shows dural invasion (extradural chordoma, large extradural - minimal intradural component, and minimal extradural - large intradural component). The tumors of 19 (26.4%), 25 (26.4%), and nine (12.5%) patients originated from the superior, middle, and inferior clivus, respectively. Nineteen (26.4%) patients had panclival involvement. GTR was performed in 47 (65.3%) the patients. The GTR rate in patients with panclival tumors was 47.3% (9/19). The experience, lateralization, dural involvement, and origin of the clivus affecting GTR were analyzed. Extradural - intradural extensions were verified as negative predictor factors for GTR, whereas tumors located in the superior (OR: 16.710, p=0.030) and middle (OR: 11.154, p=0.023) segments were positive predictive factors for GTR. CONCLUSION: An increasing experience in endoscopic surgery significantly increases the GTR rates by widening the surgical limitations. Due to dense bone infiltration and adhesion to critical neurovascular structures, recurrence rates are high despite performing GTR. Although surgery and adjuvant treatments improve the 5-year survival of patients, the mortality rates remain high. Therefore, surgery of these tumors should be performed by experienced centers. In addition to surgical and adjuvant therapies, targeted molecular and translational biological therapies are also needed for chordomas and chondrosarcomas in the future.

An endoscopic endonasal approach to craniopharyngioma via the infrachiasmatic corridor: a single center experience of 84 patients.

OBJECT: The infrachiasmatic corridor is the most important surgical access route for craniopharyngiomas and was identified and used in clinical series. The aims of this study were to describe the characteristics that assist dissection and resection rates in endoscopic surgery of solid, cystic, and recurrent cases and their importance in the infrachiasmatic corridor in endoscopic surgery. METHODS: One hundred operations on 84 patients with pathologically identified craniopharyngioma were included in the study. The MRI findings were evaluated, and the location of the lesions was classified as (1) infrasellar; (2) sellar; or (3) suprasellar. In the sagittal plane, we measured the longest diameter of cystic and solid components and the height of chiasm-sella. Images were assessed for the extent of resection and were classified as gross total resection. This was deemed as the absence of residual tumor and subtotal resection, which had residual tumor. RESULTS: The infrasellar location was reported in 7/84 (8.3%) patients, the sellar location in 8/84 (9.5%), and the suprasellar location in 69/84 (82.1%) patients. The narrow and high chiasm-sella were observed in 28/69 (40.5%) and 41/69 patients (59.4%), respectively. The mean distance of the chiasm-sella was 9.46± 3.76. Gross total tumor resection was achieved in 60/84 (71.4%) and subtotal tumor resection was performed in 24/84 (28.6%) patients. The results revealed that suprasellar location (OR: 0.068; p = 0.017) and recurrent cases (OR: 0.011; p<0.001) were negative predictive factors on GTR. Increasing the experience (OR: 42,504; p = 0.001) was a positive predictor factor for GTR. CONCLUSION: An EETS approach that uses the infrachiasmatic corridor is required for skull base lesions extending into the suprasellar area. The infrachiasmatic corridor can determine the limitations of endoscopic craniopharyngioma surgery. This corridor is a surgical safety zone for inferior approaches.

Primary pituitary abscess case series and a review of the literature.

OBJECTIVE: Pituitary abscess is a rare condition, with approximately 300 cases reported in the literature. Primary pituitary abscess, the most common type, occurs in previously healthy normal glands. Secondary pituitary abscess is secondary to pre-existing lesions in the pituitary region, such as pituitary adenoma, Rathke's cleft cysts, or craniopharyngioma and infections. MATERIAL AND METHODS: A total of 2281 patients underwent pituitary surgery via endoscopic transsphenoidal approach in Kocaeli University Pituitary Gland Research Center between 1997 and 2018. Among this cohort 9 patients (4 female and 5 male) were diagnosed with primary pituitary abscess based on both intraoperative findings and postoperative histopathological evidence. RESULTS: Primary pituitary abscess incidence was obtained 0.39% in our center. Mean age of the patients was 50 years old. There was no history of pituitary surgery, radiotherapy and infection diseases in our patients. Visual symptoms were prominent in two patients, hypopituitarism was found in 5 out of the 9 patients. All patients have typical pituitary lesion on pituitary magnetic resonance imaging. Staphylococcus species were the most commonly isolated organisms in the culture. A few weeks of antibiotic therapy were administered after surgery. CONCLUSION: Presentation of fever, headache, diabetes insipidus, hypopituitarism and a sellar cystic mass with an enhanced rim after gadolinium contrast on pituitary magnetic resonance imaging may be suggestive of a pituitary abscess. Transsphenoidal endoscopic surgery, proper antibiotics and appropriate hormone replacement therapy when necessary are the keys of pituitary abscess treatment.

Extension Pathways of Pituitary Adenomas with Cavernous Sinus Involvement and Its Surgical Approaches.

BACKGROUND: Resection and remission rates are low in pituitary adenomas that invade the cavernous sinus (CS) because of the complexity of the region. In this study, the authors describe the invasion patterns and surgical approaches for these corridors. METHODS: Endoscopic transsphenoidal surgery was performed in 1849 patients between August 1997 and 2017; 381 of these patients were included in the study because of the presence of CS invasion. CS invasion pathways and CS compartments were defined, and these patients were divided into 3 groups according to their invasion corridors. The cases were also categorized according to the Knosp classification. RESULTS: A total of 381 patients were included, 199 of whom were men. The mean follow-up duration was 34 months. In preoperative magnetic resonance imaging measurements, 2 of 381 patients had microadenoma, 350 of 381 had macroadenoma, and 29 of 381 had giant adenoma. When the early postoperative magnetic resonance images were compared with the preoperative images, 91 of 381 (23.9%) patients had subtotal tumor resection, 83 of 381 (21.8%) had near-total tumor resection, and 207 of 381 (54.3%) had gross total tumor resection. Considering the invasion classification with endoscopic confirmation, there were 168 of 381 (44.1%) cases of isolated medial corridor involvement, 74 of 381 (19.4%) cases of isolated lateral corridor involvement, and 139 of 381 (36.5%) cases of total involvement cases. CONCLUSIONS: Medial wall defect has no importance in the invasion. Similarly, seeing the existence of pitholes is not an invasion criterion. Pituitary adenomas invade 4 compartments: the superior, anteroinferior, posterior, and lateral compartments of the CS via 2 corridors. Increased experience, novel approaches, and endoscopic developments have contributed immensely to this field.

Visual Outcome of an Endoscopic Endonasal Transsphenoidal Approach in Pituitary Macroadenomas: Quantitative Assessment with Diffusion Tensor Imaging Early and Long-Term Results.

BACKGROUND: Postoperative visual recovery in patients with pituitary adenoma can be influenced by the duration of symptoms, age, and tumor volume. Diffusion tensor imaging (DTI) allows visualization of white matter structure along with quantitative information. The aims of our study were to predict the visual recovery process in the early and long-term periods and to define the parameters affecting the recovery course. METHODS: A total of 200 patients with pituitary macroadenomas underwent endoscopic transsphenoidal surgery between January 2009 and July 2016. DTI and visual analysis including visual acuity and visual field analyses were performed for these patients at 5 periods, which included 3 years of follow-up. The effects of age, duration of symptoms, and tumor volume on visual recovery were evaluated. RESULTS: Mean tumor volume was calculated as 8871 ± 2758 mm3 and mean symptom duration was 23.41 ± 3.72 weeks. Mean age of the patients was 43.8 ± 8.9 years in the full recovery group and 48.7 ± 15.1 years in the nonrecovery group. Visual field analysis results on a Humphrey visual chart showed a significant linear strong correlation with fractional anisotropy (FA) values and a reverse strong correlation with mean diffusivity (MD) values on DTI magnetic resonance. DTI FA and MD cutoff values for each group were respectively determined as 0.373 and 1386 (×10-6 mm2/second) for the preoperative period, 0.423 and 1383 (×10-6 mm2/second) for the initial period, 0.428 and 1265 (×10-6 mm2/second) for the early period, 0.432 and 1238 (×10-6 mm2/second) for the intermediate period, and 0.437 and 1198 (×10-6 mm2/second) for the late period. CONCLUSIONS: DTI can assess and predict visual recovery after endoscopic transsphenoidal surgery of patients with pituitary macroadenomas causing chiasmal compression. FA values lower than or MD values greater than the cutoff values of the specific period reflect poor prognosis. Tumor volume was found to be the featured parameter that affects visual recovery. The postoperative first year is the most prominent interval evaluating the prognosis of visual recovery.