Surfing the COVID-19 Tsunami with Teleophthalmology: the Advent of New Models of Eye Care.

Purpose of Review: In this article, we reviewed the impact resulting from the COVID-19 pandemic on the traditional model of care in ophthalmology. Recent Findings: Though virtual eye care has been present for more than 20 years, the COVID-19 pandemic has established a precedent to seriously consider its role in the evolving paradigm of vision and eye care. New hybrid models of care have enhanced or replaced traditional synchronous and asynchronous visits. The increased use of smart phoneography and mobile applications enhanced the remote examination of patients. Use of e-learning became a mainstream tool to continue accessing education and training. Summary: Teleophthalmology has demonstrated its value for screening, examining, diagnosing, monitoring treatment, and increasing access to education. However, much of the progress made following the COVID-19 pandemic is at risk of being lost as society pushes to reestablish normalcy. Further studies during the new norm are required to prove a more permanent role for virtual eye care.

Chaos in wavy-stratified fluid-fluid flow.

We perform a nonlinear analysis of a fluid-fluid wavy-stratified flow using a simplified two-fluid model (TFM), i.e., the fixed-flux model (FFM), which is an adaptation of the shallow water theory for the two-layer problem. Linear analysis using the perturbation method illustrates the short-wave physics leading to the Kelvin-Helmholtz instability (KHI). The interface dynamics are chaotic, and analysis beyond the onset of instability is required to understand the nonlinear evolution of waves. The two-equation FFM solver based on a higher-order spatiotemporal finite difference scheme is used in the current simulations. The solution methodology is verified, and the results are compared with the measurements from a laboratory-scale experiment. The finite-time Lyapunov exponent (FTLE) based on simulations is comparable and slightly higher than the autocorrelation function decay rate, consistent with previous findings. Furthermore, the FTLE is observed to be a strong function of the angle of inclination, while the root mean square of the interface height exhibits a square-root dependence. It is demonstrated that this simple 1-D FFM captures the essential chaotic features of the interface dynamics. This study also adds to a growing body of work indicating that a TFM with appropriate short wavelength physics is well-behaved and chaotic beyond the KHI.

Stereotactic disconnection of hypothalamic hamartoma to control seizure and behavior disturbance: case report and literature review.

An 18-year-old boy with refractory epilepsy and aggressiveness associated to a hypothalamic hamartoma was submitted to a stereotactically guided lesion by thermocoagulation. The target was based on magnetic resonance (MR) images merged with computed tomography scan images taken on the day of surgery while patient was on a stereotactic frame. In order to reveal structures not discernible in MR images, the Schaltenbrand digital brain atlas was merged onto the patient's images. Target and trajectory of the depth electrode were chosen based on three-dimensional imaging reconstructions. A surgical plan was devised to disconnect the hypothalamic hamartoma from the hypothalamus, medial forebrain bundle, fasciculus princeps, and dorsal longitudinal fasciculus. Our target was placed at the inferior portion of the posterolateral component of the hamartoma, bordering the normal hypothalamus. The patient evolved with marked lessening of aggressiveness. Seizure frequency was reduced from several seizures per day to less than one tonic-clonic seizure during sleep per month and only two episodes suggestive of partial complex seizures during daytime. These results have remained consistent over a 24-month postoperative follow-up. Functional neuroanatomy of hypothalamic connections involved in seizure propagation and aggressive behavior was reviewed.

Gray matter overlying anterior basal temporal sulci as an intraoperative landmark for locating the temporal horn in amygdalohippocampectomies.

OBJECTIVE: Use of the gray matter overlying the anterior portions of the occipitotemporal and rhinal sulci as an intraoperative landmark for locating the temporal horn during amygdalohippocampectomies approached by the superior or lateral surface of the temporal lobe. METHODS: The presence of occipitotemporal and rhinal sulci was analyzed in the magnetic resonance imaging scans of 165 patients who subsequently underwent mesial temporal resections, focusing on coronal slices up to 4 cm from the temporal pole. These sulci were used during surgery to locate the temporal horn in 150 surgeries. Five adult cadaveric heads whose vessels were perfused with colored silicone were used for photography. RESULTS: These sulci are the principal sulci of the anterior basal temporal lobe. They were present in 154 out of 165 and 165 out of 165 patients, respectively. When approaching mesial temporal structures from the superior or lateral surface of the temporal lobe, dissection is initially performed through the white matter toward the floor of the middle fossa until the gray matter overlying an anterior basal sulcus is encountered. Dissection continues medially and superiorly from the top of the gray matter until the temporal horn is entered. CONCLUSION: Gray matter overlying these sulci leads toward the anterior portion of the floor of the temporal horn and constitutes a landmark for locating the temporal horn. However, only the rhinal sulcus was always present. When both are present, the gray matter overlying the occipitotemporal sulcus is a reliable landmark. These landmarks are most suitable for mesial temporal resections without significant displacement of the temporal horn.

Thymus hyperplasia after resolution of hypercortisolism in ACTH-dependent Cushing's syndrome: the importance of thymic vein catheterization.

Thymic hyperplasia has been described after the resolution of hypercortisolism from several etiologies, causing great diagnostic dilemmas. We describe a case where the catheterization of the thymic vein was essential for the differential diagnosis of a thymic enlargement in an adrenalectomized patient with ACTH-dependent Cushing's syndrome. The patient was a 48-year-old female with clinical and laboratorial data suggesting Cushing's disease. She underwent a transsphenoidal surgery with no tumor visualization and no remission of the syndrome. Histopathological studies disclosed a normal pituitary. She underwent a bilateral adrenalectomy and 8 months later a chest CT showed an increase of left thymic lobe, which was previously non-existent. After a negative (111)In-pentetreotide scintigraphy, the patient underwent simultaneous and bilateral catheterism of the petrosus sinuses and catheterization of the thymic and inominate veins and no ACTH gradient was shown among the sites of collection. She did not undergo thoracotomy and a follow-up was established. During the evolution, there was a spontaneous regression of the thymic lesion 38 months after the diagnosis. The ACTH gradient during the catheterization of thymic vein was essential for the differential diagnosis of the thymic enlargement tumor after hypercortisolism resolution in ACTH-dependent Cushing's syndrome, especially in this case, where the ACTH source was occult, thus avoiding an invasive surgical procedure for a benign entity with spontaneous resolution.

Postoperative fever after hemispherectomy: the role of non-infectious factors.

Postoperative fever is a usual source of concern among caregivers and patients' family given that it may reflect a wide range of complications. The objective of this paper was to outline the expected postoperative temperature variation after hemispherectomies, and to establish factors that affect this curve. From 1987 to 2003, 30 patients were hemispherectomized in our institution. Among them, 24 patients without clinical diagnosis of infection were selected for this study. Postoperative axillary temperature from each patient was recorded over 10 days. Data was initially analyzed for all 24 patients and, later, for subgroups by (1) surgical technique (functional hemispherectomy, anatomical hemispherectomy, and hemispherotomy) and (2) hemispheric volume of the causative pathology (groups with large, moderately atrophic, and severely atrophic hemispheres). There was a trend of temperature elevation (p=0.06) over the first 4 days in all patients where 14 subjects recorded values over 38.5 degrees C, and 3 over 39.0 degrees C. Temperature curves from subgroups undergoing different techniques presented no statistical differences. However, the group including causative pathologies with larger hemispheres had a higher temperature curve when compared to patients with severely atrophic hemispheres (p<0.05). Our findings support the view that fever is an predictable event after hemispherectomies and causative pathologies with larger hemispheres present higher postoperative temperatures.

Cerebral hemodynamic changes gauged by transcranial Doppler ultrasonography in patients with posttraumatic brain swelling treated by surgical decompression.

OBJECT: The use of decompressive craniectomy has experienced a revival in the previous decade, although its actual benefit on patients' neurological outcome remains the subject of debate. A better understanding of the intracranial pressure dynamics, as well as of the metabolic and hemodynamic brain processes, may be useful in assessing the effect of this surgery on the pathophysiology of the swollen brain. The aim of this study was to use transcranial Doppler (TCD) ultrasonography to examine the hemodynamic changes in the brain after decompressive craniectomy in patients with head injury, in addition to examining the relationship between such hemodynamic changes and the patient's neurological outcome. METHODS: Nineteen patients presenting with traumatic brain swelling and cerebral herniation syndrome who had undergone decompressive craniectomy with dural expansion were studied prospectively. The TCD ultrasonography measurements were performed bilaterally in both the middle cerebral artery (MCA) and in the distal portion of the cervical internal carotid artery (ICA) immediately prior to and after surgical decompression. After surgery, the mean blood flow velocity (BFV) rose to 175 +/- 209% of preoperative values in the MCA of the operated side, while rising to 132 +/- 183% in the contralateral side; the difference between the mean BFV increase in in the MCA of both the decompressed and the opposite side reached statistical significance (p < 0.05). The mean BFV of the extracranial ICA increased to 91 +/- 119% in the surgical side and 45 +/- 60% in the opposite side. Conversely, the MCA pulsatility index (PI) values decreased, on average, to 33 +/- 36% of the preoperative value in the operated side and to 30 +/- 34% on the opposite side; the MCA PI value reductions were significantly greater in the decompressed side when compared with the contralateral side (p < 0.05). The PI of the extracranial ICA reduced, on average, to 37 +/- 23% of the initial values in the operated side and to 24 +/- 34%, contralaterally. No correlation was verified between the neurological outcome and cerebral hemodynamic changes seen on TCD ultrasonography. CONCLUSIONS: Decompressive craniectomy results in a significant elevation of cerebral BFV in most patients with traumatic brain swelling and transtentorial herniation syndrome. The increase in cerebral BFV may also occur in the side opposite the decompressed hemisphere; the cerebral BFV increase is significantly greater in the operated hemisphere than contralaterally. Concomitantly, PI values decrease significantly postoperatively, mainly in the decompressed cerebral hemisphere, indicating reduction in cerebrovascular resistance.

Hemispherectomy: a schematic review of the current techniques.

Anatomical hemispherectomy has been used for the treatment of seizures since 1938. However, it was almost abandoned in the 1960s after reports of postoperative fatalities caused by hydrocephalus, hemosiderosis, and trivial head traumas. Despite serious complications, the remarkable improvement of patients encouraged authors to carry out modifications on anatomical hemispherectomy in order to lessen its morbidity while preserving its efficacy. The effort to improve the technique generated several original procedures. This paper reviews current techniques of hemispherectomy and proposes a classification scheme based on their surgical characteristics. Techniques of hemispherectomy were sorted into two major groups: (1) those that remove completely the cortex from the hemisphere and (2) those that associate partial cortical removal and disconnection. Group 1 was subdivided into two subgroups based on the integrity of the ventricular cavity and group 2 was subdivided into three subgroups depending on the amount and location of the corticectomy. Grouping similar techniques may allow a better understanding of the distinctive features of each one and creates the possibility of comparing data from different authors.

The value of cranial computed tomography in high-risk, mildly head-injured patients.

BACKGROUND: The purpose of this article was to assess if high-risk, mildly head-injured patients with normal CT scan present an outcome similar to the group with "low-risk MHI." METHODS: A total of 379 hospital charts of inpatients with Glasgow Coma Scale scores of 13, 14, and 15 were reviewed. Information regarding age, fGCS, trauma mechanism, cranial CT scan findings, hospital course, and follow-up using the GOS were obtained from all patients. RESULTS: Patients were separated in 3 groups: fGCS 13 (46 patients), fGCS 14 (138 patients), and fGCS 15 (195 patients). The groups with different scores on fGCS did not differ regarding CT scan abnormalities, surgical treatment, or outcome. Patients were also separated in 2 groups based on CT scan findings: 266 patients had CT interpreted as abnormal and 113 had CT interpreted as normal. The 2 groups differed statistically regarding surgical treatment and scores on GOS (P < .05). There was no statistically significant difference between the 2 groups regarding sex, trauma mechanism, fGCS, or age. CONCLUSIONS: Our findings support the idea that a normal cranial CT scan in patients with fGCS scores of 13 or higher ascertain a low-risk MHI outcome and, therefore, such patients must be included in this category of traumatic brain injury. On the other hand, patients with cranial CT scan abnormalities should be included in the group with moderate head injury.

Factors of morbidity in hemispherectomies: surgical technique x pathology.

OBJECTIVE: The objective of this paper is to evaluate factors of surgical morbidity from different techniques of hemispherectomy with emphasis on causative pathology. PATIENTS AND METHODS: Thirty patients underwent hemispherectomy in our institution from 1987 to 2003, two presented with Sturge-Weber Syndrome (SWS), sixteen with Rasmussen's Syndrome (RS), eight with established hemispheric lesions (EHL), and four with cortical development malformations (CDM). Six surgeons operated on three patients using anatomical hemispherectomies (AH), 11 patients using functional hemispherectomy (FH), and 16 patients employing hemispherotomy (HT). Surgical technique and causative pathology were studied independently as factors of morbidity in hemispherectomy. RESULTS: Overall mean surgical time was 11:50+/-3:20 h and increased proportionately in pathologies with larger hemispheres. Blood transfusion was particularly influenced by the approach adopted by our team of anesthesiologists, independently of technique or pathology. Pathology was the most important factor related to hydrocephalus as two out of four patients with CDM needed ventriculoperitoneal shunt whilst none with EHL or SWS. Four patients undergoing HT and one FH presented residual bridges connecting the hemispheres, three were reoperated and are seizure free. Two patients with CDM did not improve their seizures worthwhile with surgery and other two (one with RS and other with CDM) were waiting a second procedure due to incomplete inter-hemispheric disconnection. Five patients presented infection and one died after developing meningoencephalitis. CONCLUSION: Hemispherectomies are procedures where pathology and surgical technique interact narrowly. Therefore, in order to study surgical morbidity or outcome, both pathology and technique have to be analyzed independently.

Dexmedetomidine for awake craniotomy without laryngeal mask.

OBJECTIVE: This paper reports the use of dexmedetomidine in three epileptic patients with cavernous angiomas that underwent awake surgery in order to map their speech areas. METHOD: Loading dose of dexmedetomidine varied from 1 microg/Kg/h to 3 microg/Kg/h over 20 minutes and maintenance dose from 0.4 microg/Kg/h to 0.8 microg/Kg/h. RESULTS: There was no occurrence of hemodynamic instability, convulsions or respiratory depression. Patients tolerated well the procedure. CONCLUSION: Dexmedetomidine was useful for awake craniotomy as it decreased patients level of consciousness but did not produce agitation. Laryngeal mask was not necessary to keep air ventilation.

The early years of hemispherectomy.

Today, hemispherectomy is a well-established procedure for the treatment of some sorts of catastrophic epilepsies. This, however, has not always been the case. The technique was developed to deal with brain tumors; however, the initial results were not remarkable. Moreover, when its morbidity became evident, it was almost abandoned. Had it not been for a shift in its use, with a huge increase in operations on patients with infantile hemiplegia, this surgery would certainly have disappeared. This paper focuses on the facts that surrounded these early years.

Edema and malignancy in meningiomas.

PURPOSE: In recent years there have been many attempts to define a subset of aggressive malignant meningiomas based on histopathology and imaging technologies. The purpose of this study was to evaluate the level of peritumoral edema and its volume using the imaging technologies, computer tomography and magnetic resonance imaging, and correlate these results with the histological WHO classification. Reported causes of tumoral edema and its relationships to the histological characteristics were also reviewed. METHODS: The cases of 55 patients with meningiomas who underwent surgery at the Hospital das Clinicas (Fac Med Univ Sao Paulo) between September 1993 and September 1997 were reviewed. The level of edema according to the classification of Ide et al. (1995) was compared to the histological WHO classification. RESULTS: Classification of the degree of edema was: level 0 edema--28 cases ; level I edema--19 cases; level II edema--8 cases. Histological classification was: benign meningioma--43 cases; atypical meningiomas--11 cases; malignant meningioma--1 case. There was a significant (P=.0089) correlation between the degree of tumoral edema and the histological characteristics. CONCLUSIONS: These results suggest that the degree of edema as revealed by computer tomography and magnetic resonance imaging can be an important clinical predictive factor for the histological grade of the meningioma.

Angioleiomyoma of the cavernous sinus: case report.

OBJECTIVE AND IMPORTANCE: Angioleiomyomas (ALMs) are relatively rare, benign, vascular soft tissue tumors that occur most frequently in the extremities of middle-aged individuals. To date, only two cases of intracranial ALMs have been described, both with little emphasis on the clinical, surgical, and radiological aspects. Neither of these reported cases of ALM involved the cavernous sinus. Furthermore, there is no previous intracranial ALM magnetic resonance imaging scan described in the literature. This report presents the first case of cavernous sinus ALM, emphasizing the clinical, radiological, and surgical aspects. CLINICAL PRESENTATION: A 52-year-old man had a 2-year history of horizontal diplopia and frontal headache. Facial numbness and impaired visual acuity in the previous 6 months were also reported. Physical examination revealed paralysis of right Cranial Nerves III, IV, and VI. A decrease in optical acuity was also noted. Computed tomographic and magnetic resonance imaging scans demonstrated a mass lesion located in the right cavernous sinus, which enhanced homogeneously with administration of intravenous contrast medium. INTERVENTION: A total resection was performed via a right frontotemporal craniotomy and a pretemporal approach with peeling of the middle fossa. The postoperative course was uneventful. Histological examination identified the ALM, with no recurrence noted during follow-up. CONCLUSION: It is unknown why intracranial ALMs have not been reported more frequently in the literature. Although ALMs are a rare occurrence, misinterpretation of this lesion may also have contributed to the lack of reported cases. Before surgery, ALMs can be distinguished from meningiomas and schwannomas but not from hemangiomas. The prognosis of intracranial ALM is good, as suggested in this case as well as the two previously reported cases.

Reflections on a stereotactic and functional journey: the blessing and inspiration of working among giants.

The author reports some of his early personal neurosurgical experiences spent among some of the great figures in neurosurgery and among some of the founders and pioneers of functional neurosurgery, stereotaxy, and clinical neurophysiology during the mid-1960s. This historical vignette represents recognition of the legacy of those many creative pioneers in this field of study, primarily in the areas of development of functional and stereotactic methods, epilepsy surgery, human neurophysiology, pain, movement disorders, neuroendocrine surgery, and psychiatric illnesses.

Anatomical landmarks for hemispherotomy and their clinical application.

OBJECT: The authors introduce the surgical concept of the central core of a hemisphere, from which anatomical structures are disconnected during most current hemispherotomy techniques. They also propose key anatomical landmarks for hemispherotomies that can be used to disconnect the hemisphere from its lateral surface around the insula, through the lateral ventricle toward the midline. METHODS: This anatomical study was performed in five adult cadaveric heads following perfusion of the cerebral arteries and veins with colored latex. Anatomical landmarks were used in five hemispheric deafferentations. The central core of a hemisphere consists of extreme, external, and internal capsules; claustrum; lentiform and caudate nuclei; and thalamus. Externally, this core is covered by the insula and surrounded by the fornix, choroid plexus, and lateral ventricle. During most hemispherotomies, the surgeon reaches the lateral ventricle through the frontoparietal opercula or temporal lobe; removes the mesial temporal structures; and disconnects the frontal lobe ahead, the parietal and occipital lobes behind, and the intraventricular fibers of the corpus callosum above the central core. After a temporal lobectomy, the landmarks include the choroid plexus and posterior/ascending portion of the tentorium to disconnect the parietal and occipital lobes, the callosal sulcus or distal anterior cerebral artery (ACA) to sever the intraventricular fibers of the corpus callosum, and the head of the caudate nucleus and ACA to detach the frontal lobe. CONCLUSIONS: These landmarks can be used in any hemispherotomy during which a cerebral hemisphere is disconnected from its lateral surface. Furthermore, they can be used to perform any resection around the central core of the hemisphere and the tentorial incisura.

Clinical presentation, treatment and outcome of patients with cerebral metastases: the University of São Paulo series.

INTRODUCTION: Secondary neoplasias are the most common tumors affecting the central nervous system and several clinical aspects of this disease are still controversial. METHOD: Forty-seven consecutive patients with the diagnosis of cerebral metastases (CM) were retrospectively studied at the Clinical Hospital of Sao Paulo University Medical School. Mean age was 53.9 years and 25 patients were female. RESULTS: The most frequent primary sites were breast, lung and skin. Symptoms were related to increased intracranial pressure (ICP) in 48.9%, focal neurological events in 27.7% and both in 17.0%. Single brain metastases were found in 57.4% of those cases, the frontal lobe being most frequently affected. Surgical treatment was performed in 68.1%, radiotherapy in 40.4% and chemotherapy in 17.0%. CONCLUSION: After statistical analysis, there was a trend towards prolonged survival of female patients, patients with ICP symptoms and the surgical group. Data from different centers are essential to establish the best management of CM.

Transcranial doppler sonography in two patients who underwent decompressive craniectomy for traumatic brain swelling: report of two cases.

The role of decompressive craniectomy in the treatment of severe posttraumatic cerebral swelling remains quite a controversial issue. To the best of our knowledge, there is no study demonstrating the effect of decompressive craniectomy on cerebral blood flow (CBF) velocity by means of transcranial Doppler sonography (TCD). We present two patients who developed traumatic brain swelling and uncontrollable intracranial hypertension with coma and signs of transtentorial herniation. One patient underwent bifrontal, while the second, unilateral, frontotemporoparietal decompressive craniectomy with dural expansion. In both patients, TCD examinations were performed immediately before and after surgery to study the cerebral hemodynamic changes related to the operations. Pre and postoperative TCD examinations demonstrated a significant increase in blood flow velocity in the intracranial arteries in both subjects. In conclusion, our cases suggest that decompressive craniectomy with dural expansion may result in elevation of CBF velocity in patients with massive brain swelling. The increase in CBF velocity appears to occur not only in the decompressed hemisphere, but also on the opposite side.

Epidural hematomas of the posterior cranial fossa.

OBJECT: The authors present their experience in the management of posterior fossa epidural hematoma (PFEDH), which involved an aggressive diagnostic approach with the extensive use of head computerized tomography (CT) scanning. METHODS: The authors treated 43 cases of PFEDH in one of the largest health centers in Brazil. Diagnosis was established in all patients with the aid of CT scanning because the clinical manifestations were frequently nonspecific. Cases were stratified by clinical course, Glasgow Coma Scale score, and their radiological status. Based on clinical and radiological parameters the patients underwent surgical or conservative management. CONCLUSIONS: Compared with outcomes reported in the available literature, good outcome was found in this series. This is primarily due to the broad use of CT scanning for diagnostic and observational purposes, which, in the authors' opinion, led to early diagnosis and prompt treatment.