Large language models: Are artificial intelligence-based chatbots a reliable source of patient information for spinal surgery?

PURPOSE: Large language models (LLM) have recently attracted attention because of their enormous performance. Based on artificial intelligence, LLM enable dialogic communication using quasi-natural language that approximates the quality of human communication. Thus, LLM could play an important role for patients to become informed. To evaluate the validity of an LLM in providing medical information, we used one of the first high-performance LLM (ChatGPT) on the clinical example of acute lumbar disc herniation (LDH). METHODS: Twenty-four spinal surgeons experienced in LDH surgery directed questions to ChatGPT about the clinical picture of LDH from a patient's perspective. They evaluated the quality of ChatGPT responses and its potential use in medical communication. The responses were compared with the information content of a standard informed consent form. RESULTS: ChatGPT provided good results in terms of comprehensibility, specificity, and satisfaction of responses and in terms of medical accuracy and completeness. ChatGPT was not able to provide all the information that was provided in the informed consent form, but did communicate information that was not listed there. In some cases, albeit minor, ChatGPT made medically inaccurate claims, such as listing kyphoplasty and vertebroplasty as surgical options for LDH. CONCLUSION: With the incipient use of artificial intelligence in communication, LLM will certainly become increasingly important to patients. Even if LLM are unlikely to play a role in clinical communication between physicians and patients at the moment, the opportunities-but also the risks-of this novel technology should be alertly monitored.

Assessment of Obesity as Risk Factor of Lumbar Disc Surgery: Retrospective Analysis of 598 Cases and Simulated Surgery on 3D-Printed Models.

(1) Background: Obesity poses known risks in surgery, including a prolonged operation time and postoperative complications. Given the rising obesity rates and frequent lumbar disc surgeries, understanding these risks is crucial. This study aims to assess the impact of obesity on operation duration and postoperative complications in lumbar disc prolapse surgery. (2) Methods: We retrospectively analyzed 598 patients with monosegmental disc herniation, correlating their body mass index (BMI) as a surrogate parameter for obesity with operation time. Excluding complex cases (multi-segmental herniations or recurrent herniations), complication rates and hospital stays were recorded. Simulated surgeries on 3D-printed models of varying obesity levels examined operation times and instrument suitability. (3) Results: Of these patients, 438 patients had a BMI of <30, and 160 patients had a BMI of ≥30. Complication rates showed no significant differences between groups. Linear regression analysis failed to establish a sole dependency of operation time on BMI, with R2 = 0.039 for the normal-weight group (BMI < 30) and R2 = 0.059 for the obese group (BMI ≥ 30). The simulation operations on the 3D-printed models of varying degrees of obesity showed a significant increase in the simulated operation time with higher levels of obesity. A geometrically inadequate set of surgical instruments was assumed to be a significant factor in the simulated increase in operating time. (4) Conclusions: While various factors influence operation time, obesity alone does not significantly increase it. However, simulated surgeries highlighted the impact of obesity, particularly on instrument limitations. Understanding these complexities is vital for optimizing surgical outcomes in obese patients.

[Decompressive craniectomy in traumatic brain injury and malignant brain infarction]. / Indikation und Durchführung der dekompressiven Kraniektomie.

High intracranial pressure (ICP) is the most frequent cause of death and disability after severe traumatic brain injury and malignant cerebral infarction. After failure of general therapeutic maneuvers and first line therapies, "second tier" therapies have to be considered. Decompressive craniectomy is an advanced treatment option for controlling intracranial pressure (ICP). In this review indications and techniques of decompressive craniectomy are described and current literature is discussed. The author concludes that decompressive craniectomy is no routine, but should be considered in individual cases.

Single integrated device for optical CDMA code processing in dual-code environment.

We report on the design, fabrication and performance of a matching integrated optical CDMA encoder-decoder pair based on holographic Bragg reflector technology. Simultaneous encoding/decoding operation of two multiple wavelength-hopping time-spreading codes was successfully demonstrated and shown to support two error-free OCDMA links at OC-24. A double-pass scheme was employed in the devices to enable the use of longer code length.

Diffraction-limited performance of flat-substrate reflective imaging gratings patterned by DUV photolithography.

We report on the first demonstration of flat substrate imaging gratings fabricated by deep ultraviolet (DUV) photoreduction lithography, which uniquely offers sub-100-nm resolution and spatial coherence over centimeter scales. Reflective focusing gratings, designed according to holographic principle, were fabricated on 300-mm silicon wafers by immersion DUV lithography. Spatial coherence of the fabrication process is evident in measured diffraction-limited imaging function. Flat-substrate gratings, with lines of arbitrary spacing and curvature, offer both dispersion and general spatial wavefront transformation combining the function of multiple optical elements. Fabrication at the sub-100-nm resolution level allows high-line-count, low-order efficient gratings even into the deep ultraviolet region. Nanoreplication of gratings at the wafer level provides a pathway to devices of ultimate low cost.

Demonstration of mode conversion using anti-symmetric waveguide Bragg gratings.

We experimentally demonstrate a novel grating which only produces reflection with mode conversion in a two-mode waveguide. That characteristic can improve the performance of optical devices that currently use tilted Bragg gratings to provide the mode conversion. Tilted Bragg gratings produce also reflections without mode conversion which increases noise and crosstalk of the optical device.

Juvenile psammomatoid ossifying fibroma of the neurocranium. Report of four cases.

Juvenile psammomatoid ossifying fibroma (JPOF) is a benign fibroosseous lesion predominantly arising within the paranasal sinuses in children and young adults. Neurocranial occurrence is exceedingly rare and a location within the neurocranial portion of the temporal bone has not been described. The authors report on one case of sinonasal JPOF secondarily extending into the cranial cavity and three cases primarily affecting the neurocranial bones to increase clinical awareness of this uncommon tumor, which may be easily mistaken for meningioma. Moreover, the absence of activating missense mutations of the GNAS1 gene in two cases strongly argues against a relationship between JPOF and fibrous dysplasia.

Cerebral vascular and metabolic response to sustained systemic inflammation in ovine traumatic brain injury.

Traumatic brain injury (TBI) is frequently accompanied by a systemic inflammatory response secondary to multiple trauma, shock, or infections. This study investigated the impact of sustained systemic inflammation on cerebral hemodynamics and metabolism in ovine traumatic brain injury. Fifteen sheep were investigated for 14 hours. Head injury was induced with a nonpenetrating stunner in anesthetized, ventilated animals. One group (TBI/Endo, n = 6) subsequently received a continuous endotoxin infusion for 12 hours, whereas a second group (TBI, n = 6) received the carrier. Three instrumented animals served as sham controls. Head impact significantly increased intracranial pressure from 9 +/- 4 mm Hg to 21 +/- 15 mm Hg (TBI/Endo) and from 10 +/- 3 mm Hg to 24 +/- 19 mm Hg (TBI) (means +/- SD). Internal carotid blood flow increased and cerebral vascular resistance decreased (P < 0.05) during the hyperdynamic inflammatory response between 10 and 14 hours in the TBI/Endo group, whereas these parameters were at baseline level in the TBI group. Intracranial pressure remained unchanged during this period, but increased during hypercapnia. The CMRO2, PaCO2, and arterial hematocrit values were identical among the groups between 10 and 14 hours. It is concluded that chronic endotoxemia in ovine traumatic brain injury was associated with cerebral vasodilation uncoupled from global brain metabolism. Different mechanisms appear to induce cerebral vasodilation in response to inflammation and hypercapnia.

Bioelectrical behaviour of hypoxic human neocortical tissue under the influence of nimodipine and dimethyl sulfoxide.

Nimodipine and dimethyl sulfoxide (DMSO) have been shown to affect electrophysiological responses in rodent brain tissue in an vitro model of hypoxia. In the present study, the same agents were now examined for their effects on human neocortical brain slices under repeated hypoxic conditions. DMSO (0.4%), with and without addition of nimodipine (40 micromol/l), did not increase the latency of anoxic depolarization (AD). This finding is not in line with our previous observations of DMSO effects, with and without nimodipine, on brain slices of guinea pigs. AD latency was significantly longer in human neocortical brain slices compared with hippocampal slices of rodents even without any pharmacological influence. A possible acute effect of DMSO-nimodipine may therefore be masked by an interspecies difference of hypoxia resistance.

Effects of methohexital on bioelectrical reactions in guinea pig hippocampal slices during hypoxia.

The barbiturate methohexital (42 and 140 micromol/l) was tested for an acute effect on anoxic depolarization (AD) and evoked potentials (EP) in hippocampal slices of guinea pigs exposed to repeated hypoxic conditions (n = 78). The dosages of methohexital resemble the range of plasma levels measured in patients with an intraoperative burst suppression electroencephalogram. Direct current potential and EP were recorded in the CA1 region. Hypoxia was terminated either when AD had reached its peak, or 2 min after maximum AD. Excluding the actions of methohexital on cerebral blood flow, reperfusion phase and the delayed mechanisms of cellular protection, a dose-dependent direct effect on EP even after repeated hypoxic conditions could be observed.

Different actions of gamma-hydroxybutyrate: a critical outlook.

Gamma-hydroxybutyrate acid (GHB) is a naturally occurring analog of GABA in the mammalian brain and can be therapeutically used for basic sedation in intensive care units. Although its application is discussed controversially, GHB is suspected to protect neuronal tissue against ischemic damage. GHB was tested for an acute effect on electrophysiologic parameters of guinea pig hippocampal tissues exposed to ischemic conditions. With application of 0.5 mM GHB, an acute protective effect was observed. The aim of the present paper is to discuss our experimental results as well as pathophysiological mechanisms of GHB and its clinical applicability.

Electrophysiology in ischemic neocortical brain slices: species differences vs. influences of anaesthesia and preparation.

Ischemia models are indispensable for the evaluation of measures to be clinically applied to brain trauma or stroke patients. Slice models provide good control over experimental parameters and allow for comparative examinations of human and animal brain tissue. Experimental tissue, however, may be altered by anaesthesia, preparatory technique, and, in the case of human tissue, by underlying diseases. These influences on tissue behaviour under ischemia were examined electrophysiologically. Native rat tissue slices were prepared either immediately after decapitation (n = 13), during short ether/barbiturate narcosis (n = 18), or after two hours of inhalation anaesthesia (n = 12) imitating clinical narcosis. Tissue from rats in which generalized amygdala-kindled seizures had been triggered by electric stimulation (n = 10) was prepared according to the decapitation protocol, while human tissue (n = 10) was obtained during epilepsy or tumour surgery. Electrophysiological data (latency and amplitude of anoxic depolarization, recovery of evoked potentials) were recorded during ischemia simulation. Neither details of preparation or anaesthesia nor a history of epileptic fits were associated with significant changes of electrophysiological reactions under ischemia. Human tissue showed a significantly higher ability to uphold transmembrane ion gradients under ischemia. The ability of brain tissue to withstand ischemia is obviously species dependent. For the transfer of experimental results into clinical use it is important that interspecies differences alone can bring about a significant change of tissue behaviour.

Optical add-drop multiplexers based on the antisymmetric waveguide Bragg grating.

A novel optical add-drop multiplexer (OADM) based on a null coupler with an antisymmetric grating was designed and experimentally demonstrated. The antisymmetric grating exclusively produces a reflection with mode conversion in a two-mode waveguide. This improves the performance compared with previous demonstrations that used tilted Bragg gratings. Our design minimizes noise and cross talk produced by reflection without mode conversion. In addition, operational bandwidth and, versatility are improved while the compactness and simplicity of the null coupler OADM are maintained.

Cerebral response to norepinephrine compared with fluid resuscitation in ovine traumatic brain injury and systemic inflammation.

OBJECTIVE: Traumatic brain injury is frequently accompanied by a systemic inflammatory response. Systemic inflammation was associated with cerebral hyperperfusion uncoupled to global oxygen metabolism in ovine head trauma. The present study investigated the cerebral effects of cerebral perfusion pressure (CPP) management performed by either fluid resuscitation or vasopressor treatment of low CPP induced by systemic inflammation. DESIGN: Nonrandomized experimental study. SETTING: University hospital laboratory. SUBJECTS: A total of 12 adult sheep. INTERVENTIONS, MEASUREMENTS, AND MAIN RESULTS: Sheep were anesthetized and ventilated throughout the experimental period (13 hrs). After baseline measurements (hour 0), blunt head trauma was induced by a nonpenetrating stunner. After postinjury measurements (hour 2), all animals received continuous endotoxin infusion. At hour 10, one group (n = 6) was infused with hydroxyethyl starch until CPP reached 60-70 mm Hg. A second group (n = 6) received norepinephrine for CPP elevation. In the norepinephrine group, blood was isovolemically exchanged by hydroxyethyl starch to achieve comparable hematocrit levels. Head trauma increased intracranial pressure and decreased brain tissue oxygen tension. Endotoxemia induced a hyperdynamic cardiovascular response with increased internal carotid blood flow in the presence of systemic hypotension and decreased CPP. Hydroxyethyl starch infusion further increased internal carotid blood flow from (mean +/- sd) 247 +/- 26 (hour 10) to 342 +/- 42 mL/min (hour 13) and intracranial pressure from 20 +/- 4 (hour 10) to a maximum of 25 +/- 3 mm Hg (hour 12) but did not significantly affect brain tissue oxygen tension, sinus venous oxygen saturation and oxygen extraction fraction. Norepinephrine increased internal carotid blood flow from 268 +/- 19 to 342 +/- 58 mL/min and intracranial pressure from 22 +/- 11 to 24 +/- 11 mm Hg (hour 10 vs. hour 13) but significantly increased sinus venous oxygen saturation from 49 +/- 4 (hour 10) to a maximum of 59 +/- 6 mm Hg (hour 12) and decreased oxygen extraction fraction. The increase in brain tissue oxygen tension during norepinephrine treatment was not significant. CONCLUSION: We conclude that despite identical carotid blood flows, only CPP management with norepinephrine reduced the cerebral oxygen deficit in this model.

Low-loss silica-on-silicon two-dimensional Fabry-Perot cavity based on holographic Bragg reflectors.

We report on the demonstration of an integrated slab-waveguide-based concentric Fabry-Perot resonator that employs holographic Bragg reflectors as cavity mirrors. The cavity, produced in a low-loss silica-on-silicon slab waveguide by high-fidelity deep-ultraviolet photolithographic fabrication, exhibits a reflectivity-limited Q factor of approximately 10(5). Increasing the mirror's reflectivity will provide Q values similar to those of silica-based ring resonators, whereas the folded Fabry-Perot resonator design allows access to a substantially larger free spectral range by cavity shortening.

Wavelength division multiplexing based on apodized planar holographic Bragg reflectors.

We report wavelength division multiplexing based on lithographically fabricated slab-waveguide-contained planar holographic Bragg reflectors (HBRs). Partial HBR diffractive contour writing and contour displacement are successfully demonstrated to enable precise bandpass engineering of multiplexer transfer functions and make possible compact-footprint devices based on hologram overlay. Four- and eight-channel multiplexers with channel spacings of approximately 50 and approximately 100 GHz, improved sidelobe suppression, and flattop passbands are demonstrated. When a second-order apodization effect, comprising effective waveguide refractive-index variation with written contour fraction, and the effect of hologram overlap on the hologram reflective amplitude are included in the simulation, excellent agreement between predicted and observed spectral passband profiles is obtained. With demonstrated simulation capability, the ability to fabricate general desired passband profiles becomes tractable.

Effective gray scale in lithographically scribed planar holographic Bragg reflectors.

We demonstrate that holographic Bragg reflector grating structures, which are photolithographically scribed in planar waveguides, support a unique approach to apodization and overlay that uses fixed-depth etching and partial contour writing to achieve continuous reflective amplitude control.

Bandpass engineering of lithographically scribed channel-waveguide Bragg gratings.

We propose and demonstrate a powerful approach to spectral bandpass engineering (apodization) of one-dimensional channel-waveguide Bragg reflectors. Bandpass engineering is accomplished by precise photolithographic control of the length and the longitudinal placement of individual grating lines, which provides unique line-by-line diffractive amplitude and phase control. Channel-waveguide gratings that exhibit complex filtering functions have been fabricated and modeled. When a second-order apodization effect that comprises effective waveguide refractive-index variation with grating-line length is included in the simulation, extraordinary agreement between predicted and observed spectral passband profiles is obtained.