Dura Incision Research Articles

Surgery for Pineal Region Tumors: Concept and Technical Aspects of Occipital Transtentorial Approach

This article describes the concept and technical aspects of the occipital transtentorial approach(OTA)for tumor extraction in the pineal region, based on the author's experience and literature review. Awareness of the successful completion of each surgical step is essential. Preoperative preparation and imaging evaluations, with particular attention to the veins and venous sinuses, are especially important. It is also helpful to perform a complete dura incision and inversion up to the edge of confluence, superior sagittal sinus, and transverse sinus. Subsequently, it is necessary to understand the usefulness of adequate dissection in the vicinity of the corpus callosum and internal occipital vein(IOV)so that the occipital lobe can be moved without difficulty. Furthermore, development of the IOV with adequate tentoriotomy facilitates contralateral work. Finally, complete understanding of each step during the bilateral, ambient cistern and cerebellomesencephalic fissure dissection process, where the cerebellar vermis can be moved without difficulty, is necessary for a safe OTA to pineal region tumor extraction.

Evaluation of Inferior Intercavernous Sinus in Patients With Pituitary Microadenoma by Contrast-Enhanced SPACE Imaging.

Inferior intercavernous sinus (iICS) is a venous channel below the pituitary gland. Inferior intercavernous sinus injury is predisposed to cause venous bleeding during dura incision in transsphenoidal surgery for pituitary adenomas. Therefore, this study aimed to perform a radiological assessment of iICS before transsphenoidal surgery for pituitary microadenoma. A retrospective evaluation was performed on 156 patients who underwent magnetic resonance imaging examinations in our hospital before endoscopic transsphenoidal surgery for pituitary microadenoma. Both sagittal reformatted and coronal contrast-enhanced (CE) sampling perfection with application optimized contrast using different flip angle evolutions (SPACE) images were interpreted for the presence, shape, and size of the iICS. In CE SPACE, the iICS was identified in 72 patients (46.15%) with pituitary microadenoma. The iICS was appeared as a filiform-shaped hyperintense structure below the pituitary gland on coronal CE SPACE planes and a crescent-shaped hyperintense structure on sagittal CE SPACE planes. The mean ± SD width, depth, and height of iICS were 11.15 ± 3.47 mm, 5.29 ± 1.24 mm, and 1.41 ± 0.19 mm, respectively. Contrast-enhanced SPACE may serve as a promising technique in evaluating iICS and individualized preoperative planning before transsphenoidal surgery for pituitary microadenoma.

A Modified Dura Puncture Procedure to Reduce Brain Shift in Deep Brain Stimulation Surgery: One Institution's Experience.

ObjectiveThe therapeutic effect of deep brain stimulation (DBS) surgery mainly depends on the accuracy of electrode placement and the reduction in brain shift. Among the standard procedures, cerebrospinal fluid (CSF) loss or pneumocephalus caused by dura incision (DI) is thought to be the main reason for brain shift and inaccuracy of electrode placement. In the current study, we described a modified dura puncture (DP) procedure to reduce brain shift and compare it with the general procedure of DBS surgery in terms of electrode placement accuracy.Materials and MethodsWe retrospectively analyzed a series of 132 patients who underwent DBS surgery in Wuhan Union Hospital from December 2015 to April 2021. According to the different surgery procedures, patients were classified into two cohorts: the DI group (DI cohort) had 49 patients who receive the general procedure, and the DP group (DP cohort) had 83 patients who receive the modified procedure. Postoperative pneumocephalus volume (PPV) and CSF loss volume, electrode fusion error (EFE), and trajectory number were calculated. Meanwhile, intraoperative electrophysiological signal length (IESL), electrode implantation duration, and other parameters were analyzed.ResultsIn the current study, we introduced an improved electrode implantation procedure for DBS surgery named the DP procedure. Compared with the general DI cohort (n = 49), the modified DP cohort (n = 83) had a shorter electrode implantation duration (p < 0.0001), smaller PPV, lower CSF leakage volume (p < 0.0001), and smaller EFE (p < 0.0001). There was no significant difference in IESL (p > 0.05) or adverse events (perioperative cerebral haematoma, skin erosion, epilepsy, p > 0.05) between the two cohorts.ConclusionThe DP procedure is a modified procedure that can reduce brain shift and ensure implantation accuracy during DBS surgery without adverse events.

Intradural disc herniation: A case report and literature review

Background: Intradural disc herniation (IDH) is rare and is thought to be caused by posterior longitudinal ligament and posterior adhesions. MRI findings are inadequate for definitive diagnosis. We reported a patient with an L4-5 IDH and reviewed the literature.&#x0D; Case Description: A 71-year-old male patient presented with acute exacerbation of right lower extremity radiculopathy. MRI with/without contrast suggested IDH and spinal cord compression at the L4-5 spine level. While elective surgery was planned for the patient who did not have motor deficits at the time of admission, he underwent emergency surgery due to sudden urinary incontinence. At surgery, the disc herniation was appropriately resected, the dura was closed.&#x0D; Conclusion: Although MRI is helpful in the diagnosis of IDH, the definitive diagnosis is made intraoperatively. In surgery, both the extradural and intradural disc components should be removed and as small laminectomy and dura incision as possible.

Evaluation of augmented-reality based navigation for brain tumor surgery

To date, several researchers have introduced augmented reality navigation (ARN) into neurological surgery. While its application in brain tumor surgery seems promising, reports on its utility have been limited, thus warranting further evaluation. To clarify the stages and approaches in which ARN is useful and assess the effect of presurgical discussion with surgeons, we assessed usefulness using a hand-held ARN system we had developed, which displays three-dimensional (3D) virtual structures overlaid on a real-time image of the surgical field via a tablet PC monitor. The system was tested in 20 patients undergoing various procedures, with the first 10 consecutive cases being unselected and the following 10 cases being selected, for whom 3D models were prepared per the surgeons’ request. Thereafter, the surgeons ranked its usefulness during each stage of surgery. Consequently, case selection and presurgical discussions with surgeons considerably improved the usefulness, with the “useful” gradings improving from 50% to 88% across all surgical stages. Accordingly, usefulness improved from 50% to 90%, 67% to 100%, and 40% to 80% during the skin incision and craniotomy, dura incision, and intradural procedure stages, respectively. ARN was useful for superficial tumor resection, but less so for deep-seated tumor resection, except when using the transcortical and interhemispheric approaches. In conclusion, a tablet-type ARN can be useful during skin incisions, craniotomy and dura incisions, superficial tumor resections, and transcortical and interhemispheric approaches for deep-seated tumors. Case selection and presurgical discussions with surgeons were essential for the efficacy of ARN.

Spinal arachnoid web—a distinct entity of focal arachnopathy with favorable long-term outcome after surgical resection: analysis of a multicenter patient population

BACKGROUND CONTEXTSpinal arachnoid web (SAW) is a rare condition characterized by focal thickening of the arachnoid membrane causing displacement and compression of the spinal cord with progressive symptoms and neurological deficits. Recent reports and clinical experience suggest that SAW is a distinct entity with specific radiological findings and treatment strategies distinguishable from other arachnopathies and potential differential diagnoses. PURPOSETo better define the diagnostic and clinical features, treatment options and outcomes of surgically treated SAW. STUDY DESIGNMulticentric retrospective cohort study. PATIENT SAMPLETwelve cases of SAW surgically treated at three different centers. OUTCOME MEASURESSelf-reported and neurological outcome measurements (pain, sensory-motor deficits, vegetative dysfunctions) were assessed at follow-up timepoints. METHODSRetrospective review of prospectively collected data on all patients surgically treated for SAW from three participating neurosurgical centers between 2014 and 2020. Clinicopathological data, including neurological presentation, radiological and histological findings and outcome data were analyzed. RESULTSTwelve radiologically and surgically confirmed cases of SAW were analyzed. Mean patient age was 54.7 [±12.7], 67% were male. All SAWs were located in the posterior thoracic dural sac. On magnetic resonance imaging (MRI), the “scalpel sign” - a characteristic focal dorsal indentation of the spinal cord resembling a scalpel blade - was identified in all patients. A focal intramedullary syrinx was present in 83%. Preoperative clinical symptoms included signs of myelopathy, pain, weakness and sensory loss, most commonly affecting the trunk/upper back or lower extremities. Laminectomy or laminoplasty with intradural excision of the SAW was the surgical treatment of choice in all cases. Intraoperative ultrasound was valuable to visualize the cerebrospinal fluid (CSF) flow obstruction, confirm the SAW location before dura incision and to control adequacy of resection. After surgery, sensory loss and weakness in particular showed significant improvement. CONCLUSIONSThe present study comprises the largest series of surgically treated SAW, underscoring the unique clinical, radiographic, histopathological, and surgical findings. We want to emphasize SAW being a distinct entity of spinal arachnopathy with a favorable long-term outcome if diagnosed correctly and treated surgically. Intraoperative ultrasound aids visualizing the SAW before dural incision, as well as verifying restored CSF flow after resection.

Ultrasound Doppler examination in the surgical treatment of pituitary adenomas with cavernous sinus extension

Objective: To determine the effectiveness of intraoperative Doppler ultrasound in the surgical treatment of pituitary adenomas with invasive parasellar growth into the cavernous sinus Knosp 3 and Knosp 4. Material and Methods. During 2009–2017, 71 patients with pituitary adenomas (PA) with extension into the cavernous sinus Knosp 3 and Knosp 4 were retrospectively reviewed. According to the size PA were divided into pituitary macroadenomas, (from 10 to 40 mm) in 45 (63.4%) patients, and giant PA (over 40 mm) – in 26 (36.6%) patients. Cavernous sinus invasion Knosp 3 and 4 was identified in 47 (66.2%) and 24 (33.8%) patients respectively. Non-secreting PA - 43 (60.5%) patients and hormone-secreting PA - 28 patients (39.4%). Endoscopic endonasal trassphenoidal (EET) approach was used in all cases. Laterally expanded EET (LEEET) approach was used in 29 cases. Intraoperative Doppler ultrasound (IDUS) was used in 36 (51%) cases. Results. Intraoperative Doppler ultrasound was used in cases of Knosp 3 extension in 23 (32.4%) cases and in Knosp 4 - in 13 (18.3%) cases. Gross total resection, including extension into the cavernous sinus using IDUS was achieved in 22 (62.7%) patients. In cases where IDUS was not used, gross total resection was achieved in 19 (52.7%) cases. In cases where the IDUS was not used, recurrence rate was 7.3%, with IDUS - 5%. Biochemical remission was achieved in 22 (78.6%) cases. Liquorrhea nasalis after surgery was observed in 6 (8.4%) cases, meningoencephalitis - in 1 (1.4%) case, oculomotor palsy -3 (4.2%) cases. Conclusions. Intraoperative Doppler ultrasound is an informative method that provides safe resection of pituitary adenomas with cavernous sinus extension with a low level of possible postoperative complications. Parasellar extension of Pituitary adenomas into the cavernous sinus Knosp 4 significantly reduces the possibility of gross total resection. However, the use of intraoperative ultrasound makes it possible to determine safe boundaries for manipulation both medially and laterally from the internal carotid artery, increasing the level of radicality and the duration of clinical remission. Intraoperative Doppler ultrasound during endoscopic endonasal transsphenoidal surgery of pituitary adenomas with parasellar extension allows to identify the internal carotid artery in the tumor stroma with the existing changed skull base anatomy. Dura incision under intraoperative Doppler ultrasound reduces the risk of internal carotid artery injury.

A Case of Chronic Invasive Actinomycosis in the Nasal Cavity

A 57-year-old male patient with nasal congestion and nasal congestion, which occurred 1 month prior to the hospital visited. PNS CT and MRI was performed and revealed right orbital cellulitis, sinusitis and brain abcess. Surgical drainage was determined by rhinology, ophthalmology and neurosurgery. The right sphenoid sinus was identified as an open mucosal mucosa, and blackish mucosa was found on the right sphenoid sinus. Eucleation was performed. Infected orbital tissue removal and orbital abscess drainage were performed. Neurosurgery performed dura incision, drainage and removal of a large amount of abscess pattern, and duroplasty with artificial dura. Actinomyces odontolyti was identified by pus culture, and postoperative antibiotic treatment and dressing were performed, but infection aggravation persisted, resulting in deterioration of general condition, multiple organ damage, and cerebral infarction.

Comparison of intraoperative cortisol levels after preoperative hydrocortisone administration versus placebo in patients without adrenal insufficiency undergoing endoscopic transsphenoidal removal of nonfunctioning pituitary adenomas: a double-blind randomized trial.

In this double-blind randomized trial, the necessity of preoperative steroid administration in patients without adrenal insufficiency (AI) undergoing endoscopic transsphenoidal surgery (ETSS) for pituitary adenoma was evaluated. Forty patients with and without AI, defined as a peak cortisol level > 18 µg/dl on the insulin tolerance test or rapid adrenocorticotropic hormone (ACTH) test, undergoing ETSS for nonfunctioning pituitary adenomas were randomly allocated to treatment with either 100 mg of preoperative hydrocortisone (group HC, n = 20) or normal saline (group C, n = 20). The patients with pituitary apoplexy, the use of a drug within the last 3 months that could affect the hypothalamic-pituitary-adrenal axis, or a previous history of brain or adrenal surgery were excluded. Intraoperative cortisol and ACTH levels were measured after anesthesia induction, dura incision, and tumor removal, and at the end of surgery. Intraoperative hypotension, early postoperative AI, and postoperative 3-month pituitary function were investigated. Intraoperative serum cortisol levels were significantly higher in the HC group than in the C group after anesthesia induction (median 69.0 µg/dl [IQR 62.2-89.6 µg/dl] vs 12.7 µg/dl [IQR 8.4-18.2 µg/dl], median difference 57.5 µg/dl [95% CI 33.0-172.9 µg/dl]), after dura incision (median 53.2 µg/dl [IQR 44.9-63.8 µg/dl] vs 6.4 [IQR 4.8-9.2 µg/dl], median difference 46.6 µg/dl [95% CI 13.3-89.2 µg/dl]), after tumor removal (median 49.5 µg/dl [IQR 43.6-62.4 µg/dl] vs 9.2 µg/dl [IQR 5.75-16.7 µg/dl], median difference 39.4 µg/dl [95% CI 0.3-78.1 µg/dl]), and at the end of surgery (median 46.9 µg/dl [IQR 40.1-63.4 µg/dl] vs 16.9 µg/dl [IQR 12.1-23.2 µg/dl], median difference 32.2 µg/dl [95% CI -42.0 to 228.1 µg/dl]). Serum ACTH levels were significantly lower in group HC than in group C after anesthesia induction (median 3.9 pmol/L [IQR 1.7-5.2 pmol/L] vs 6.9 pmol/L [IQR 3.9-11.9 pmol/L], p = 0.007). No patient showed intraoperative hypotension due to AI. Early postoperative AI was observed in 3 and 5 patients in groups HC and C, respectively. The postoperative 3-month pituitary hormone outcomes including ACTH deficiency were not different between groups. Preoperative steroid administration may be unnecessary in patients without AI undergoing ETSS for nonfunctioning pituitary adenomas. However, a further large-scale study is needed to determine whether preoperative steroid administration has a significant impact on clinically meaningful events such as perioperative AI and postoperative 3-month ACTH deficiency in these patients.Korean Clinical Trial Registry no.: KCT0002426 (https://cris.nih.go.kr/cris/).

Intraoperative point-of-care assessment of an inflammatory biomarker in chronic subdural hematomas: Technical note

ObjectiveInflammatory processes have been associated with the development and recurrence of chronic subdural hematomas (cSDH). Elevated levels of presepsin, a truncated N-terminal fragment of soluble CD14, occur in various inflammatory conditions of bacterial and non-bacterial origin. Here we report on our initial experiences with the intraoperative point-of-care (POC) assessment of presepsin in patients treated for cSDH. Patients and methodsThe POC analyser Pathfast® was used in 21 patients treated for cSDH at our institution. Prior to surgery, levels of C-reactive protein (CRP) and white blood cells (WBC) were assessed. After burr hole trephination and dura incision, samples of subdural fluid and whole blood were collected and immediately assessed with the POC analyser. Values of presepin were compared between samples of the subdural compartment and whole blood. ResultsPresepsin levels were assessed within 13 min in all patients and no technical difficulties occurred. Compared to the reported normal range values of presepsin (55–184 pg/mL), mean levels of presepsin in samples of the subdural compartiment was increased more than 5-fold (821 ± 110.1 pg/mL). Furthermore, mean presepsin values in samples of the subdural compartiment were significantly higher than in samples of whole blood (154.8 ± 19.2 pg/mL; p < 0.0001). ConclusionPOC assessment of the inflammatory biomarker presepsin is feasible within minutes during surgical treatment of cSDH. Corresponding to previous studies, presepsin levels were highly elevated in the subdural fluid, indicating processes of inflammation. Whether results of intraoperative POC assessment of inflammatory biomarkers is associated with outcome parameters in patients treated for cSDH has to be addressed in further studies. In our view, there is a role for this promising technique in improving future treatment strategies in respective patients.

Transpalpebral approach in skull base surgery: how I do it.

Keyhole surgery has been actively developing in the last two decades. Modern neuroimaging, preoperative individual planning, and innovative neurosurgical equipment allow us to operate through mini craniotomy with minimization of approach-related complications. Preoperative planning is very critical. After the patient positioning, skin incision, craniotomy, and dura incision are performed. Intradural lesion is reached with standard microneurosurgical technique. A watertight dura closure is important. Transpalpebral approach can be good alternative to traditional, extended fronto-lateral craniotomies with excellent cosmetic and functional outcomes. Adequate selection of patients is important.

Supraorbital approach through eyebrow skin incision for aneurysm clipping: how I do it.

Surgery has been in a huge development where the aim is to achieve same or better results with less complication in a less invasive way; these minimal approaches can be applied in a very safe way to aneurysmal neurosurgery. Images are studied to optimize the patient positioning and the surgical roadmap. After the positioning, the skin incision, craniotomy, and dura incision are performed and intradural lesion is reached. A watertight closure is performed under the microscope. The keyhole approach requires some adaption from the side of the surgeon and can be performed only in cases envisioned to have no increased risk for the patient.

Microscope and Fiberscope-assisted Subarachnoid-Subarachnoid (S-S) Bypass: A Novel Surgical Technique to Reestablish Cerebrospinal Fluid Flow in Treating Dorsal Spinal Arachnoid Webs, Diagnosed by Cine-MRI.

A "dorsal spinal arachnoid web" is the thickened arachnoid band on the surface of the spinal cord which disturbs the cerebrospinal fluid (CSF) flow, known as a rare cause of thoracic myelopathy. The ideal treatment is controversial because of the risk of readhesion after simple resection of the web. A subarachnoid-subarachnoid bypass is a method to reestablish CSF flow through a silicon tube between the cranial and caudal subarachnoid space. This method is reported to be useful for traumatic syringomyelia, adhesive arachnoiditis, etc. We applied this technique for arachnoid webs with the assistance of a microscope and fiberscope. After a dura incision, the thickened arachnoid web can be seen fluttering within the CSF flow inside the arachnoid space, which partitions the subarachnoid space into cranial and caudal parts. After opening the subarachnoid space and resection of the web under a microscope, the fiberscope is inserted toward the cranial and caudal directions to check for the presence of another arachnoid web. If another web is found, it is penetrated using a guiding wire. Then, a silicone tube is inserted into the cranial and caudal normal subarachnoid space. In this paper, we would like to introduce this technique.

Direct Current Coupled Recordings of Cortical Spreading Depression Using Silicone Probes.

Electrophysiological assessment of infraslow (<0.1 Hz) brain activities such as cortical spreading depression (SD), which occurs in a number of pathologies including migraine, epilepsy, traumatic brain injury (TBI) and brain ischemia requires direct current (DC) coupled recordings of local field potentials (LFPs). Here, we describe how DC-coupled recordings can be performed using high-density iridium electrode arrays (silicone probes). We found that the DC voltage offset of the silicone probe is large and often exceeds the amplifier input range. Introduction of an offset compensation chain at the signal ground efficiently minimized the DC offsets. Silicone probe DC-coupled recordings across layers of the rat visual and barrel cortices revealed that epipial application of KCl, dura incision or pinprick TBI induced SD which preferentially propagated through the supragranular layers and further spread to the granular and infragranular layers attaining maximal amplitudes of ~−30 mV in the infragranular layers. SD at the superficial cortical layers was nearly two-fold longer than at the deep cortical layers. Continuous epipial KCl evoked multiple recurrent SDs which always started in the supragranular layers but often failed to propagate through the deeper cortical layers. Intracortical KCl injection into the infragranular layers evoked SD which also started in the supragranular layers and spread to the granular and infragranular layers, further indicating that the supragranular layers are particularly prone to SD. Thus, DC-coupled recordings with silicone probes after offset compensation can be successfully used to explore the spatial—temporal dynamics of SD and other slow brain activities.

Treatment strategy and efficacy for moyamoya disease of different clinical types and radiographic stages

Objective To assess the therapeutic strategies and efficacy of moyamoya disease of different clinical types and radiographic stages.Methods The clinical types,radiographic stages and treatment strategies of 39 patients with moyamoya disease,who were treated in our medical centers from April 2010 to December 2013,were retrospectively analyzed.The treatment efficacies were analyzed by CT angiography,CT perfusion and DSA.The average follow-up time was(21.3±3.1)months(range:7-44months).Results Thirty-four patients had typeⅠ-Ⅴ moyamoya disease,including 6treated by encephoduro-myo-synangiosis(EDMS)and 28 by STA-MCA anastomosis combined with EDMS,with 4receiving a second surgery on the other hemisphere 6months after first surgery.Five patients with typeⅥ moyamoya disease underwent emergency surgery:cerebral hematoma evacuation+decompressive craniectomy+EDMS.Stage Ⅰ and Ⅱ patients were treated by conservative therapies.StageⅢ-Ⅵ patients were treated by EC-IC cerebrovascular reconstruction.The skin incision,bone window,and dura incision were designed individually in order to protect anastomoses formed pre-op in stageⅤ Ⅵ patients.All patients had improved clinical condition during follow-up.CTP imaging showed significantly increased relative cerebral blood flow and relative cerebral blood volume,and decreased time-to-peak after the operation(P0.05),and these changes were intensified with the prolong of follow-up.Conclusion Selection of appropriate treatment strategy according to different clinical types and radiographic stages can achieve better therapeutic efficacy for moyamoya disease patients.

Dura Incision in Petrosal Approach with Preservation of Superior Petrosal Vein: Technical Note

Dura Incision in Petrosal Approach with Preservation of Superior Petrosal Vein: Technical Note

Lumbar intraspinal arachnoid cyst superimposed by hyperacute spinal subdural hematoma: an unusual case

Background context Lumbar intradural arachnoid cyst (AC) concomitant with hyperacute spinal subdural hematoma (SSDH) has never been reported in the literature. Purpose To report a case of lumbar AC superimposed by hyperacute SSDH, which was difficult to diagnose preoperatively using magnetic resonance imaging. Herein, we describe diagrams showing the proposed mechanisms underlying the formation of a symptomatic AC. Study design/setting The study was designed to be a case report and literature review. Methods A 65-year-old man presented with acute onset of low back pain, followed by 5-day history of numbness and weakness in both legs before admission. Magnetic resonance imaging of the lumbosacral spine revealed an intradural extramedullary biconvex lesion at the L3–L4 level; the lesion compressed the cauda equina posteriorly. The lesion mainly appeared as hyperintense on T2-weighted images and hypointense on T1-weighted images. On the basis of these findings, the lesion was preoperatively diagnosed as a symptomatic lumbar subdural AC that compressed the cauda equina. Results The patient underwent laminectomy from L2 to L4. After a dura incision, a partially organized subdural hematoma was noted. Beneath the subdural hematoma was an AC compressing the underlying nerve roots. The patient’s back pain and muscle strength markedly improved after the operation. Conclusions Preoperative diagnosis of concomitant hyperacute SSDH and AC is difficult. In cases of patients who present with intraspinal AC accompanied by an acute onset of clinical presentation, an associated etiology should be considered until proven otherwise.

Changes of Endothelin and Calcitonin Gene-related Peptide Concentrations in Plasma During Propofol Anesthesia

We had previously reported that plasma concentrations of endothelin (ET) decreased significantly in the operating room during desflurane anesthesia. The purpose of the present study was to explore whether changes in plasma ET and calcitonin gene-related peptide (CGRP) concentrations were altered during propofol anesthesia in patients undergoing clipping of an intracranial aneurysm. Forty-five patients scheduled for selective craniotomy and aneurysm clipping were anesthetized with propofol. A catheter was inserted into the radial artery for blood sampling before anesthesia. Serial plasma concentrations of ET and CGRP were determined before induction, after dura incision, after clipping of the aneurysm, and 30 minutes after clipping. ET concentrations in the plasma increased significantly after clipping of the aneurysm compared with concentrations after dura incision. However, no significant changes in ET levels were found after anesthesia. Plasma concentrations of CGRP decreased significantly during anesthesia. This evidence suggests that direct stimulation of the intracalvarium blood vessel before aneurysm clipping may increase ET; however, propofol did not decrease ET, in contrast with our previously reported findings for desflurane anesthesia. Considering the well-recognized vasodilatory effect of CGRP, it is possible that a decrease in the plasma concentration of CGRP plays a role in the pathogenesis of cerebral vasospasm, which is often seen postoperatively.

Tissue-compatible and adhesive polyion complex hydrogels composed of amphiphilic phospholipid polymers

To investigate the tissue adhesive function of a hydrogel composed of biocompatible amphiphilic polymers, polymers with various architectures were prepared from 2-methacryloyloxyethyl phosphorylcholine (MPC), electrolyte monomers and hydrophobic n-butyl methacrylate (BMA). A polyion complex (PIC) hydrogel was formed within a few minutes after aqueous solutions containing the cationic and anionic MPC polymers were mixed. Provided the electrical charge of the cationic and anionic MPC polymers was approximately balanced, the PIC hydrogel existed stably in a large amount of aqueous medium. The results of the fluorescence study of the MPC polymers suggested that dissociation was suppressed and that the electrostatic interaction was enhanced in the block and graft polymers compared to the random polymers. This is due to the strategically designed architectures and the hydrophobic BMA units. Based on the results of the cytotoxicity test, the cytotoxicity of the MPC polymers was lower than that of glutaraldehyde, a cross-linker contained in aldehydetype tissue adhesives. The cationic MPC polymers demonstrated higher cytotoxicity compared to the anionic ones, which demonstrated no significant cytotoxicity at examined concentrations. The tissue adhesion of the PIC hydrogels was evaluated with a dura incision model. The results indicated that the tissue adhesion strength of the PIC hydrogel was lower than that of a commercially available fibrin glue. However, the tissue adhesion strength increased with an increase in the polymer concentration and could be controlled by the water content of the hydrogel. Although further investigation of the biocompatibility of the PIC hydrogels and control of the water content is crucial, it can be concluded that the PIC hydrogels formed by the amphiphilic MPC polymers can be promising tissue adhesives which demonstrate properties according to the architectures and chemical structures.

Changes of endothelin and calcitonin gene-related peptide during desflurane anesthesia in patients undergoing intracranial aneurysm clipping.

The purpose of this study was to explore whether the changes of plasma concentrations of endothelin (ET) and calcitonin gene-related peptide (CGRP) were possibly involved during desflurane anesthesia in patients undergoing intracranial aneurysm clipping. Forty-five consecutive patients scheduled for selective craniotomy and aneurysm clipping were anesthetized with desflurane in oxygen. Radial arterial catheter was inserted for blood sampling before anesthesia. Serial plasma concentrations of ET and CGRP were measured with radioimmunoassay prior to induction, after dura incision, after clipping of the aneurysm, and 30 minutes after clipping the aneurysm, respectively. Plasma concentrations of ET decreased significantly during the anesthesia and surgery compared with the baseline. An observed decrease in mean CGRP during anesthesia and surgery was not statistically significant. Considering the well-recognized vasoconstrictive effect of ET, it is possible that a decrease in its plasma concentration plays a role in the prevention of the acute cerebral vasospasm during desflurane anesthesia in patients undergoing intracranial aneurysm clipping.