The application of augmented reality–based navigation for accurate target acquisition of deep brain sites: advances in neurosurgical guidance

OBJECTIVE The objective of this study is to quantify the navigational accuracy of an advanced augmented reality (AR)–based guidance system for neurological surgery, biopsy, and/or other minimally invasive neurological surgical procedures. METHODS Five burr holes were drilled through a plastic cranium, and 5 optical fiducials (AprilTags) printed with CT-visible ink were placed on the frontal, temporal, and parietal bones of a human skull model. Three 0.5-mm-diameter targets were mounted in the interior of the skull on nylon posts near the level of the tentorium cerebelli and the pituitary fossa. The skull was filled with ballistic gelatin to simulate brain tissue. A CT scan was taken and virtual needle tracts were annotated on the preoperative 3D workstation for the combination of 3 targets and 5 access holes (15 target tracts). The resulting annotated study was uploaded to and launched by VisAR software operating on the HoloLens 2 holographic visor by viewing an encrypted, printed QR code assigned to the study by the preoperative workstation. The DICOM images were converted to 3D holograms and registered to the skull by alignment of the holographic fiducials with the AprilTags attached to the skull. Five volunteers, familiar with the VisAR, used the software/visor combination to navigate an 18-gauge needle/trocar through the series of burr holes to the target, resulting in 70 data points (15 for 4 users and 10 for 1 user). After each attempt the needle was left in the skull, supported by the ballistic gelatin, and a high-resolution CT was taken. Radial error and angle of error were determined using vector coordinates. Summary statistics were calculated individually and collectively. RESULTS The combined angle of error of was 2.30° ± 1.28°. The mean radial error for users was 3.62 ± 1.71 mm. The mean target depth was 85.41 mm. CONCLUSIONS The mean radial error and angle of error with the associated variance measures demonstrates that VisAR navigation may have utility for guiding a small needle to neural lesions, or targets within an accuracy of 3.62 mm. These values are sufficiently accurate for the navigation of many neurological procedures such as ventriculostomy.

THE VARIABILITY AND THE RATIO OF THE PITUITARY GLAND AND PITUITARY FOSSA LINEAR PARAMETERS DEPENDING ON THE SKULL BASE ANGLE

Details of the morpho- & topometric variability of the skull elements and soft tissue formations in the area of the sphenoid bone body, as well as their relationship, serve as the basis for the choice of proper surgical accesses to the respective area. The aim of this study was to identify the typical variability of morphometric parameters and the volume ratio between the pituitary gland and the Turkish saddle pituitary fossa in mature age adults. The method of computer craniometry (involving 100 MRI of people of the first and second periods of their mature age, 22–60) was employed to study the typical variability of the pituitary fossa and pituitary gland linear parameters, regardless of gender. The obtained data revealed that the regularity of morphometric variability and the volume ratio of the pituitary gland and the pituitary fossa depend on the skull base bending angle.

Multiple endocrine neoplasia type 1 with a frameshift mutation in its gene accompanied by a giant cervical lipoma and multiple fatty deposits in the pancreas: case report

Background Multiple endocrine neoplasia type 1 (MEN1) is a syndrome characterized by pituitary neoplasia, primary hyperparathyroidism and pancreatic endocrine tumor. Here we show a case of MEN1 with a germline frameshift mutation in its gene accompanied by a giant cervical lipoma and multiple fatty deposits in the pancreas. Case presentation A 28-year-old man noticed the decreased visual acuity of both eyes and visited our institution. Since he was diagnosed as visual disturbance and brain computer tomography (CT) showed a mass in the pituitary fossa, he was hospitalized in our institution. Endoscopic trans-sphenoidal hypophysectomy and total parathyroidectomy with auto-transplantation were performed, and a giant cervical lipoma was resected. Furthermore, in genetic search, we found a germline frameshift mutation in MEN1 gene leading to the appearance of a new stop codon. Conclusions We should bear in m ind that giant skin lipoma and multiple abnormal fatty deposits in the pancreas could be complicated with MEN1.

A Novel Intraoperative Ultrasound Probe for Transsphenoidal Surgery: First-in-human study

Background. Ultrasound has been explored as an alternative, less bulky, less time-consuming and less expensive means of intraoperative imaging in pituitary surgery. However, its use has been limited by the size of its probes relative to the transsphenoidal corridor. We developed a novel prototype that is more slender than previously reported forward-viewing probes and, in this report, we assess its feasibility and safety in an initial patient cohort. Method. The probe was integrated into the transsphenoidal approach in patients with pituitary adenoma, following a single-centre prospective proof of concept study design, as defined by the Innovation, Development, Exploration, Assessment and Long-Term Study (IDEAL) guidelines for assessing innovation in surgery (IDEAL stage 1 – Idea phase). Results. The probe was employed in 5 cases, and its ability to be used alongside the standard surgical equipment was demonstrated in each case. No adverse events were encountered. The average surgical time was 20 minutes longer than that of 30 contemporaneous cases operated without intraoperative ultrasound. Conclusion. We demonstrate the safety and feasibility of our novel ultrasound probe during transsphenoidal procedures to the pituitary fossa, and, as a next step, plan to integrate the device into a surgical navigation system (IDEAL Stage 2a – Development phase).

Empty Sella Prevalence: Step By Step

An empty sella (ES), also known as an empty sella turcica (empty pituitary fossa) is defined as an intrasellar herniation of subarachnoid space within the sella which leads to flattening of the pituitary gland towards the posteroinferior wall. Purpose — to analyze studies of ES prevalence in the world. Methods — We carried out a systematic search in both Russian and English databases (E-library, PubMed, GoogleScholar, OxfordPress, ClinicalKeys) using keywords “empty sella”, “empty sella turcica”, “empty pituitary fossa”, “prevalence” and their combinations. The period of search: 2000-2020. It is also worth noting that earlier publications of historical interest were included in the review. Results — We have analyzed 23 studies. They can be roughly devided into two groups: the first group – screening studies of ES, the second group – targeted studies of ES.

Rathke’s Cyst and Adrenal Insufficiency: A Rare Case of Hyponatremia

Background: Hyponatremia is the most common electrolyte abnormality encountered in clinical practice, the diagnosis of which can be challenging. A holistic approach with appropriate investigations is imperative to its diagnosis and management. We report this peculiar case of a patient with hypopituitarism secondary to Rathke’s cyst resulting in secondary Adrenal Insufficiency, thus causing Hyponatremia. Case Details: A 32 year male was admitted to hospital with an intractable headache and deterioration in his general wellbeing. His admission parameters revealed a GCS of 15 with normal observations. He had no evidence of meningism and examination of all other systems was unremarkable. He was not on any regular medications and there was no history of trauma. Bloods revealed a Sodium of 122mmol/l, the rest being normal. Investigations including a CT brain, CXR, paired serum & urine osmolality, urinary sodium, Thyroid functions and a 9am cortisol were conducted. Radiological imaging was unremarkable. Subsequently, he was fluid restricted due to a euvolemic fluid status. Serum osmolality was 246 mmol/kg (275-295 mmol/kg), Urine osmolality 847 mmol/kg, urine sodium 85 mmol/l and a 9 am serum cortisol of 29 nmol/L, in keeping with Adrenal Insufficiency. A further decline in his Sodium to 116 mmol/L resulted in Hyponatremic Encephalopathy. In view of impending Adrenal crisis, IV hydrocortisone was commenced in conjunction with hypertonic Saline. This was followed by strict monitoring with cautious correction. An anterior Pituitary profile, serum testosterone and Prolactin were requested. Serum Testosterone levels were 0.4nmol/L (10.0-36nmol/L), FSH- 2.5 IU/L (1.0-11.0 IU/L) and LH- 1.9 IU/L (1.5-9.3 IU/L). Serum prolactin was 85mU/L (45-375 mU/L), TSH- 0.59 mU/L (0.30-6.00 mU/L), Free T4- 13.0 pmol/L (10.4-24.5 pmol/L), IGF1-135 ug/L (60-197 ug/L). This was suggestive of partial hypopituitarism. An MRI Pituitary revealed appearances in keeping with a Rathke’s cyst occupying the pituitary fossa without compromise of the Optic Chiasma. Once stable, he was safely discharged with follow-up appointments planned with the Endocrine and Neurosurgical teams. Discussion: Rathke cleft cysts are non-neoplastic cysts arising from the embryological remnants of Rathke’s pouch in the pituitary gland. Hormonal and visual manifestations can occur if these cysts enlarge and interfere with the Pituitary production and optic chiasma. A proposed mechanism causing Hyponatremia in the context of Cortisol deficiency is increased hypothalamic secretion of Corticotropin releasing hormone (CRH), a Vasopressin secretagogue. Cortisol feeds back negatively on CRH, which is removed with adrenal insufficiency. Hyponatremia is thus often seen in patients with adrenal insufficiency, caused by an inappropriate increase in vasopressin due to cortisol deficiency and inability to excrete free water.

Change in Character of Headache in a Young Female Patient With Prolactin Secreting Pituitary Adenoma Complicated With Mild Hemorrhage

Background: Prolactin (PRL) secreting tumors are the most common functional neoplasms of the pituitary and are commonly subdivided into microprolactinomas (<10 mm) and macroprolactinomas (≥10 mm) according to their baseline diameter. The diagnosis of macroadenomas is usually straightforward and these large tumors may be associated with mass effects such as severe headache, nerve palsies or visual changes. Hyperprolactinemia can be due to other causes like pregnancy, drugs, hypothyroidism, and pituitary stalk effect should be considered in the differential. Clinical Case: A 30 year female having symptoms of prolactinoma showing amenorrhea of 3 years, galactorrhea, decrease libido who presented to the clinic for headache recently associated with anxiety. Headache initially frequently with 2-3 times in a week, moderate intensity lasting few hours, on one side of head and sometimes on the forehead, associated with blurry vision. Patient was on oral contraception taking on and off, but not on any medication currently. Initial work up consistent with hyperprolactinemia: elevated prolactin level 737.6 ng/ml (n 3.0-30 ng/ml), however other pituitary hormones are within normal limit, ACTH 32 pg/ml (n 6-50 pg/ml),FSH 3.2 mid/ml, LH 0.3miu/ml, total testosterone 13 ng/dl (n 2-35 ng/dl),TSH 1.6 mid/l (N 0.35-3.7 mid/l), FT4 0.92 ng/dl (N 0.76-1.46 ng/dl), human growth hormone <0.1ng/ml (N <=7.1 ng/dl), random cortisol 14.6 ug/dl (N 4.3-22.4 ug/dl). Pregnancy test is also negative. MRI Brain with and without contrast revealed a mass within the pituitary fossa producing smooth depression of the floor and suprasellar extension just the right of midline producing mild impingement on the undersurface of the optic chiasm, craniocaudal dimension of the tumor approximately 1.85 cm by 1.8 cm mediolateral by 1.4 cm anteroposterior without encasement or diminution of carotid arteries flow. Within the sella there is a spherical collection of T1 high signal displaying a fluid level strongly concerning for hemorrhage within the pre-existing tumor. There is no prior CT Head or MRI Brain available. Ophthalmology evaluation showed normal dilated retinal exam and no visual field defects. Medical treatment with Cabergoline 0.25 mg PO twice weekly was given on the visit, however patient did not start it yet and repeat prolactin level with 629 ng/ml. Patient endorsed that headache is better with less frequent about once in two weeks but still with absence of menstruation. Conclusion: This is the case of prolactin secreting pituitary macroadenoma with the change in character of headache due to hemorrhage in the tumor, having gradual improvement of headache which may be due to spontaneous resolving of hemorrhage from the pre-existing pituitary mass. It is very important to inform the patient with pituitary tumor go to ED if there is change in headache or vision.​

Case Report: A Case of Pituitary Adenoma Producing Growth Hormone and Thyroid-Stimulating Hormone Simultaneously

BackgroundPituitary adenoma producing growth hormone (GH) or thyroid-stimulating hormone (TSH) is characterized by various specific symptoms and/or findings. However, the frequency of pituitary adenoma producing both hormones is relatively low. In this report, we show a case of pituitary adenoma producing both GH and TSH simultaneously.Case presentationA 27-year-old woman was diagnosed as acromegaly based on various symptoms and clinical findings. For further examination and treatment, she was hospitalized in our institution. It was likely that this subject had pituitary adenoma producing both GH and TSH. In brain magnetic resonance imaging, there was a giant tumor around pituitary fossa. After the diagnosis of GH- and TSH-producing pituitary adenoma, pituitary tumor resection and cyber knife therapy were performed. In addition, we started additional treatment with somatostatin analog and GH receptor antagonist. After then, GH and insulin-like growth factor (IGF-1) levels were suppressed. After the operation, since thyroid function was not sufficiently suppressed, we started anti-thyroid drug thiamazole. After then, thyroid function was normalized and we stopped thiamazole. In GH and TSH staining, many GH-positive and TSH-positive cells were observed. These findings further confirmed our diagnosis that the pituitary adenoma in this subject produced both GH and TSH simultaneously.ConclusionsWe should bear in mind the possibility of pituitary adenoma producing both GH and TSH at the same time.

An Original Method for Removing and Fixing the Pituitary Gland of Sexually Mature Rats for Creating High-Quality Permanent Histological Preparations

The issue of high-quality creating histological preparations is an urgent issue of histology and pathological anatomy, experimental medicine and biology. The pituitary gland belongs to the smallest in mass and size of the endocrine glands in both humans and animals, it is an endocrine gland and occupies one of the central places in the endocrine regulation of the body's vital activity. The study of the features of the removal of the pituitary gland from Turkish saddle of the sphenoid bone of the skull of rats remains an important aspect of modern morphology. The purpose of the work was to develop an original technique for improving the first (removal) and second (material fixation) stages of creating histological preparations of the rat pituitary gland for morphological, morphometric, and immunohistochemical medico-biological experimental studies. Material and methods. The development of the methodology was carried out on 200 white sexually mature rats of different sex weighing 250-300 g at the age of 7-8 months in accordance with the National and European bioethical standards. Results and discussion. Modification of the technique of extracting the pituitary gland of rats includes the introduction of the animal into thiopental anesthesia, decapitation, separation of the skin and muscular integument of the head, resection of the occipital bone of the skull, exposure and removal of the brain, identification of the pituitary gland, followed by removal of the pituitary gland with a single complex (block) together with the pituitary fossa Turkish saddle and fragments of the sphenoid bone adjacent to it. The gland was fixed with a reduced concentration of a 5% solution of buffered neutral formalin. After 15-18 hours from the beginning of fixation, the complex was temporarily removed from the fixator, and the pituitary gland was removed from the pituitary fossa of Turkish saddle using eye scalpel and eye forceps. The organ had a well-fixed and compacted capsule, which prevented unnecessary trauma and fragmentation of the organ during removal. The removed pituitary gland was again immersed in a 5% solution of neutral buffered formalin for 2-3 hours. After the end of the fixation period, the pituitary gland had a well-fixed structure and was subject to the following standard stages of making permanent histological specimens

Sphenoid sinus aspergilloma clinically mimicking as malignancy—a case report

Background Fungal sphenoid sinusitis mimicking as malignant tumor and invading the pituitary fossa is an uncommon entity. This report aims to highlight radiological salient features to help differentiate fungal lesion from malignant tumor in sphenoidal sinus mass lesions. Case presentation We intend to report a case of middle-aged female who presented with gradual progressive diminution of vision since 3 years complicated with acute attack of unilateral headache and numbness. Computed tomography (CT) showed hyperdense lesion involving the sphenoid sinus extending into pituitary fossa and bilateral cavernous sinuses with smooth bony remodeling. Lesion appeared hypointense on T2-weighted and hyperintense on T1-weighted images on magnetic resonance imaging (MRI). Surgical excision of the lesion was done and pathological examination showed fungal hyphae and aspergillus fumigatus species on culture after 2 weeks of incubation. Post-operative CT revealed empty sinuses with surrounding bone remodeling. Conclusion Combination of T1 hyperintensity, T2 hypointensity, and hyperdense sinus is a strong predictor of fungal mass lesion involving sphenoid sinus.