Expanded Endoscopic Endonasal Transtuberculum Approach for Resection of Germ Cell Tumor.

We present the case of a 16-year-old with short stature, fatigue, memory impairment, and pituitary gland failure. Imaging and cerebrospinal fluid (CSF) studies supported the diagnosis of a suprasellar nongerminomatous germ cell tumor with no clear radiologic disease in the spine; however, a single atypical cell was present in the CSF. After a period of external drainage via an Ommaya device, he was treated with chemotherapy, followed by craniospinal radiation. Three months post completion of chemoradiotherapy, he had ongoing residual macroscopic enhancing disease anatomically located in the basal third ventricle and intimately related to pituitary stalk and basal thalamoperforators. In order to maximize his chance of progression-free survival, a decision was made to surgically resect the lesion via an expanded endoscopic endonasal approach with planned stalk sacrifice because of the known pituitary gland failure. In Video 1, the technical nuances underpinning the use of an expanded endoscopic endonasal transtuberculum transchiasmatic sulcus approach to resect the adherent lesion in a postradiated field in its entirety are presented. We emphasize the strategies for perforator preservation including thalamoperforators and superior hypophyseal arteries to avoid ischemic injury and visual dysfunction, respectively. Postoperative scans demonstrated gross total resection without any ischemic injury. The patient was discharged without any neurologic deficit, visual dysfunction, or CSF leak.

Surgical resection of giant extrasellar thyrotropinoma: Use of orbitozygomatic and endoscopic endonasal approach.

Background: Thyrotropinomas (TSHoma) are rare pituitary adenomas. Case Description: A 34-year-old female presented with mild bitemporal field defect in third trimester with intact pituitary function. MRI demonstrated an enhancing lesion from the posterior planum to suprasellar, interpeduncular and prepontine cisterns with chiasmal compression and right fetal posterior communicating artery encasement. With no sellar expansion, the differentials included meningioma or craniopharyngioma. She underwent a postpartum expanded endoscopic endonasal transtuberculum transchiasmatic sulcus approach [Video 1]. The lesion was debulked in the chiasmatic cistern to decompress the chiasm with preservation of superior hypophyseal perforators. Pituitary transposition and midclival approach to access the retrosellar component was not undertaken pending formal histology as the lesion encased the perforators and was atypical for the outlined differentials. In addition, the diaphragm was intact. Postoperatively, visual field normalized and the patient developed mild diabetes insipidus. Following the diagnosis of TSHoma (with an abnormal thyroid function test [TFT]) and due to patient preference and slightly increased risk of CSF leak with revisional endoscopic procedure, she underwent an orbitozygomatic craniotomy (pretemporal and transsylvian approach) without tentorial division to resect the disease in the interpeduncular and prepontine cisterns [Video 1]. The anatomical triangles and tumor characteristics facilitated this. A residual cuff was left along the base of the stalk and the floor of the third ventricle to preserve the superior hypophyseal and thalamoperforators. Postoperatively, the patient had normal TFT without any neurological deficit. Conclusion: Operative treatment strategy is presented for a rare large challenging multicompartmental extrasellar TSHoma using endoscopic endonasal and open skull base approaches.

Endoscopic Endonasal Approach for Resection of Suprasellar Hemangioblastoma: Selective Pituitary Sacrifice and Use of Indocyanine Dye: 2-Dimensional Operative Video.

Suprasellar hemangioblastomas are rare lesions occurring sporadically or more commonly with von Hippel Lindau disease (VHLD).1,2 A 27-yr-old female presented with amenorrhea, mildly raised prolactin levels and otherwise normal pituitary function, homonymous hemianopia, and mild cognitive decline. Imaging revealed a large suprasellar lesion arising from the infundibulum, causing compression of optic chiasm with edema in the visual pathways. Lesion appeared hypervascular with prominent feeding vessels from the internal carotid arteries bilaterally. To access these vessels derived from the superior hypophyseal arteries and allow early devascularization, endoscopic endonasal approach was performed.3 Stalk preservation was deemed unlikely. After opening of the suprasellar dura, indocyanine dye allowed early identification of the feeding vessels. They were sequentially sacrificed, allowing early devascularization while preserving the normal blood supply to the optic chiasm from the superior hypophyseal arteries. Pituitary gland and stalk were removed with the latter being completely involved by tumor to provide access to the retroclival region and posterior circulation. After opening of the dura underlying the dorsum sella, inferior pole of the tumor was exposed with blood supply identified from the posterior communicating arteries but not the basilar or posterior cerebral arteries. Devascularized lesion was safely removed from the optic apparatus, hypothalamus, and the third ventricle. Histology was consistent with hemangoblastoma (VHLD negative). Patient's cognitive and visual function normalized with a postoperative magnetic resonance imagingdemonstrating complete resection, no ischemic events on diffusion-weighted imaging, and resolution of the edema in the hypothalamus and visual pathways.1 She was started on desmopressin and replacement therapy for pituitary function. The patient consented to the procedure. Patient provided consent for publication.

Multivariable control of grinding plants: a comparative simulation study.

In this paper five multivariable adaptive and classical control strategies have been studied and implemented in a simulator of the copper grinding plant of CODELCO-Andina. The strategies presented were compared and, according to theory, exhibit good behavior. The extended horizon, pole-placement and model reference multivariable adaptive control strategies were formulated in discrete-time and use a model of the plant whose parameters are updated on line using the recursive least squares method along with UD factorization of the covariance matrix and variable forgetting factor. The direct Nyquist array and sequential loop closing techniques were also studied and simulated. The two-by-two multivariable system chosen to represent the grinding plant has the percentage of solids (density) of the pulp fed to the hydrocyclones (which is highly correlated with the percentage of +65 mesh in the overflow of hydrocyclones) and the sump level as output (controlled) variables. The water flow added to the sump and the speed of the pump are its input (manipulated) variables. All the algorithms tested by simulation exhibited good performance and were able to control the grinding plant in a stable fashion. Adaptive algorithms showed better performance than classical techniques, with the extended horizon and pole-placement algorithms proving to be the best. The fact that adaptive algorithms continuously adjust their parameters renders such controllers superior to those based on fixed parameters.