A Novel Approach to Support Quality Assurance (QA) of Intensity Modulated Neutron Therapy (IMNT)

PURPOSE/OBJECTIVE(S)

Neutron therapy is a form of high linear energy transfer (LET) radiation treatment shown to be beneficial for the treatment of locally advanced head and neck cancers (HNC) resistant to low LET x-ray and proton therapy treatments. The Clinical Neutron Therapy System (CNTS) at our institution has been in clinical operation for over 35 years, and over 3,400 patients have been treated using 3D conformal neutron radiation therapy. In October of 2022, the clinical commissioning of IMNT was completed and the first-ever patient was treated. A novel patient specific quality assurance (PSQA) program has been developed to support IMNT. We present an analysis of our early experiences and PSQA findings for the first 16+ patients treated with IMNT.

MATERIALS/METHODS

Our pre-treatment IMNT PSQA program includes (1) ionization chamber measurements, (2) a log-file analysis of treatment delivery, and (3) a γ-analysis of the expected and measured doses (fluences) from a novel positron emission portal imaging system based on 12C(n,2n)11C reactions. Patient setup is confirmed on a daily basis with kV portal imaging. We use a modulation factor (MF), defined as the total number of monitor units (MU)/prescribed dose (cGy) per fraction, to identify and help anticipate IMNT plans that may fail our PSQA program.

RESULTS

We have found that IMNT treatments for large, irregularly shaped treatment volumes (e.g., chest wall or head and neck cancers that require treatment of nodes in the lower neck) are more likely to fail PSQA when the MF exceeds 3 MU/cGy. For smaller, more spherical treatment volumes (e.g., base of tongue cancers), plans with a MF up to 3.5 MU/cGy pass our PSQA criteria. Re-optimized plans subsequently passed PSQA with insignificant or no change in tumor coverage and organ-at-risk (OAR) dose. Re-optimized plans also reduced the total number of MU and number of segments, which has the added benefit of decreasing the overall treatment time and patient time on the table. About 10% of early IMNT patients have required plan re-optimization.

CONCLUSION

Our pre-treatment clinical PSQA program and workflow provides useful information to guide IMNT treatment planning and delivery, and helps ensure the safe and accurate delivery of IMNT. Our early experiences suggest IMNT plans with smaller MF values are more likely to pass PSQA than plans with larger values of the MF.

Efficacy of Single-Fraction Postoperative Radiotherapy in Resected, Early-Stage Merkel Cell Carcinoma with High-Risk Features

PURPOSE/OBJECTIVE(S)

Merkel cell carcinoma (MCC) is an aggressive skin cancer with a high recurrence risk. Postoperative radiotherapy (PORT) improves the local recurrence rate (LRR) in early-stage MCC with risk factors per NCCN guidelines: primary tumor size > 1cm, head/neck (HN) location, immunosuppression, lymphovascular invasion (LVI), and positive/narrow surgical margins. Conventionally fractionated PORT (C-PORT, ∼50 Gy in 25 fractions) is often recommended for localized MCC with these risk factors; however, some institutions elect observation. Prior studies suggest LRR of ∼20% for stage I/II MCC with high-risk features managed with surgery alone. C-PORT significantly decreases LRR but may cause significant morbidity and financial toxicity. We have previously reported that single fraction (SF)-PORT with 8 Gy achieves high rates of in-field control both in the metastatic and adjuvant settings with minimal morbidity. Here, we present updated long-term outcomes of SF-PORT, offered as an alternative to C-PORT with the hypothesis that it improves LRR relative to observation while minimizing toxicity, for resected stage I/II MCC.

MATERIALS/METHODS

A retrospective, single-institution analysis was completed for stage I/II MCC patients receiving SF-PORT following surgical management. The primary objective was estimating the LRR, defined as recurrence within 2 cm of the primary tumor. Patients with resected, stage I/II MCC with at least one high-risk feature were offered C-PORT as standard of care or SF-PORT as an alternative.

RESULTS

Forty-six patients (median age: 74.5; range 50-96 years) received SF-PORT to the primary tumor site at a median 44 days after wide local excision (85%), shave/excisional biopsy (13%), or Mohs (2%). Fifty-four percent of patients had 1 high-risk feature, 35% had 2, and 11% had 3 or more. HN (74%) was the most common primary site, 26% of tumors were > 1cm, 26% were LVI+, and 15% of patients were immunosuppressed (pathological margin status was often not available). There were no local recurrences (LRR = 0%) at a median follow-up time of 2.3 years. In-field locoregional control was 96% (44/46 patients) with 2 in-field, regional recurrences observed in draining nodal basins of HN primary lesions. There were 2 out-of-field regional nodal recurrences (1 patient with IMS; neither received elective nodal SFRT). Of 9 patients who received elective nodal SF-PORT, 8 did not have a successful sentinel lymph node biopsy. No MCC-specific deaths were observed. The most common side effect was in-field, grade 1 erythema (13%); no side effects > grade 1 (CTCAE v5) were noted.

CONCLUSION

SF-PORT is associated with a very low LRR which has proven durable with long-term follow-up. The LRR for SF-PORT appears lower than historical controls treated with surgery alone for patients with resected, stage I/II MCC with high-risk features.

Proton Radiation Therapy for Stage IIA/IIB Testicular Seminoma

PURPOSE/OBJECTIVE(S)

Testicular seminoma affects young men and is associated with very favorable prognosis. The evolution in treatment paradigm has focused on minimizing acute and especially late toxicities. Following orchiectomy, while surveillance is favored in Stage I patients, radiotherapy (RT) is a standard treatment option for de novo or relapsed stage IIA or select non-bulky stage IIB disease. Despite low doses, standard RT fields to paraaortic and pelvic lymphatics using x-rays exposes a large volume of uninvolved normal tissue/viscera to excess dose. This young patient population is especially vulnerable to risks of late RT toxicities including secondary malignancy. Proton beam therapy (PBT) has dosimetric advantage over x-ray-based RT due to lack of exit dose, and comparative dosimetric/modeling studies show significant sparing of uninvolved abdominal/pelvic organs. However, there is scant reported clinical data at this time for PBT. We review our early institutional outcomes with PBT for testicular seminoma.

MATERIALS/METHODS

Single institution retrospective review from a tertiary care center of patients treated with PBT from 2013-2022 for testicular seminoma. Recurrence free (RFS) and overall survival (OS) were calculated from the completion of PBT. Toxicities were graded (Gr) using CTCAE v5.0.

RESULTS

Four patients underwent PBT, median age 39 (range 36-47). All were Stage I at diagnosis (pT1b n = 3; pT2 n = 1) and were treated for recurrent stage II disease (IIA n = 3; IIB n = 1) at a median of 34 months from orchiectomy (range 3 - 74 months). Nodal extent included 2 with multiple paraaortic nodes, 1 with solitary paraaortic node and 1 with solitary pelvic node. PBT was delivered with pencil-beam scanning, treating paraaortic + ipsilateral pelvic fields (20 Gy in 10 fractions), then sequential boost to involved nodes (10 -16 Gy in 5-8 fractions). Typically, PA or posterior oblique fields were used to minimize dose to out-of-field abdominal/pelvic viscera. Treatment was well tolerated with minimal acute toxicities: fatigue Gr 1 (n = 3), nausea Gr 1 (n = 3). No Gr 2 or higher acute toxicities or significant late toxicities were observed. At median follow up of 30 months (range 3 - 54), no recurrences were observed, and RFS and OS were 100%. Two patients are without evidence of disease > 4 years post-treatment.

CONCLUSION

In this case series, PBT for retroperitoneal and pelvic metastases in Stage IIA/IIB testicular seminoma was associated with oncologic efficacy with minimal toxicity. PBT reduces unnecessary dose to abdominal/pelvic organs compared to x-ray techniques, which is advantageous in young patients who have anticipated long-term survival. This is one of the few series reporting clinical outcomes of PBT in the management of seminoma. Randomized comparisons with x-ray approaches are impractical given the relatively low volume of patients receiving RT in modern seminoma management, so it is essential to report and track longitudinal outcomes across institutions to validate this approach.

Clinicopathologic Features of Prostate Cancer with Mesorectal Lymph Node Involvement on PSMA or Fluciclovine PET/CT

PURPOSE/OBJECTIVE(S)

Advanced PET imaging has shown more prevalent mesorectal lymph node (LN) involvement in prostate cancer than previously appreciated. The clinical features predicting risk for mesorectal involvement are not well established and the prognostic impact is unclear. This may have implications on management including radiotherapy field design. This study aims to identify clinical and pathologic characteristics associated with mesorectal involvement identified on PSMA or fluciclovine PET/CT.

MATERIALS/METHODS

We conducted a single institution retrospective review of prostate cancer patients with F-18 fluciclovine, F-18 piflufolastat, or Ga-68 gozetotide PET between January 2020 and 2023 demonstrating tracer-avid mesorectal LN in the setting of newly diagnosed disease (ND) or biochemical failure after curative-intent therapy (BF). Clinical characteristics, pathologic findings, and early clinical outcomes were reviewed.

RESULTS

We identified 16 ND and 34 BF patients with uptake in at least one mesorectal LN on PET. For ND patients, clinical features at initial diagnosis were median PSA of 35.2 (range 9.6-659), median grade group 5, and 87% with clinical or radiographic T3/T4 disease. Radiographic PET staging among ND patients (excluding mesorectal LNs) were 19% N0M0, 25% N1M0, 56% as N1M1. For BF patients, clinical features at initial diagnosis were median PSA 9.2 (range 4.1-90) and median grade group 4. Primary treatment was prostatectomy in most (91%), with a high rate of high-risk features: 68% pT3-4, 28% pN1, and 32% had persistent detectable postop PSA. Radiographic PET staging among BF patients (excluding mesorectal LNs) were 29% N0M0, 38% N1M0, 12% N0M1, and 21% as N1M1. High-risk histologic features (cribriform, intraductal, ductal, or neuroendocrine) were identified in 88% of ND and 48% BF patients. Of these patients, 86% had cribriform pattern. Median PSA prior to PET for ND and BF patients was 37.0 (range 8.5-659) and 1.9 (0.2-11.1). Median interval from initial therapy to PET for BF patients was 4.4yr (range 0.2-19.7). Median follow-up post-PET was 8.7mo (range 3.4-29) for ND and 8.8mo (range 0-76) for BF patients. Of patients with M0 PET staging, none of the 7 ND patients developed DMs, and 1 of 23 BF patients developed DM after 4 yrs.

CONCLUSION

In this analysis of prostate cancer patients with mesorectal involvement, we found a high incidence of high grade, T3-4 disease, and cribriform pattern, especially in ND patients. For BF patients, there was a high incidence of pT3-4 and pN1 disease at time of initial treatment. Overall, most patients had concurrent regional nodal disease on PET. Longer follow up of clinical outcomes and comparison to high-risk patients without mesorectal LN involvement is needed to understand the prognostic significance and predictors of mesorectal LN spread. Additional studies are needed to identify patients at highest risk in whom elective coverage of mesorectal lymphatics with elective pelvic nodal RT may be warranted.

Gastrointestinal Toxicity Following Proton and Photon Radiation for Prostate Cancer in Patients with Inflammatory Bowel Disease

PURPOSE/OBJECTIVE(S)

Inflammatory bowel disease (IBD) has been considered a relative contraindication for radiation for prostate cancer (PC) due to concern for gastrointestinal (GI) toxicity. Modern radiation planning techniques such as intensity modulated radiation therapy (IMRT) have resulted in a significant decrease in GI toxicity in the general PC population. Several published case series have suggested overall excellent outcomes using IMRT in PC patients with IBD. Proton therapy (PT) with improved dosimetric sparing of bowel and rectum may offer additional benefit, but to our knowledge, there is no published data assessing outcomes after PT in PC patients with IBD. We report our institutional experience treating PC patients with IBD with both PT and IMRT.

MATERIALS/METHODS

We identified patients with an IBD diagnosis treated for PC at our institution from 2012-2022 with either IMRT or PT. Baseline clinical characteristics were captured, along with radiation parameters, including dose, fractionation, inclusion of pelvic nodes, and use of a rectal spacer. IBD specifics captured included type of IBD, use of IBD medication, and pre radiation colonoscopy findings when available. Early and late GI toxicities were captured via retrospective chart review and graded per the Common Terminology Criteria for Adverse Events (CTCAE) version 5.

RESULTS

Eighteen patients with IBD were treated with RT for PC at our institution, including 10 with ulcerative colitis, 7 with Crohn's disease, and 1 with IBD NOS. Nine of these patients were treated with PT and 9 with IMRT. Most were treated with conventional fractionation (n = 14) and the rest with moderate hypofractionation. Fourteen received primary RT to an intact prostate, and the rest received salvage RT. In four patients, the pelvic nodes were also treated. Rectal spacers were used for 8 patients. Nine of the patients were on IBD medications, and of the 15 patients with records of pre-RT colonoscopy, only 1 demonstrated inflammatory findings, which were noted in the ileum. Median follow-up was 3.5 years (1-6) Acute grade (Gr)1 GI toxicity was seen in 6(33%) patients with diarrhea and proctitis. No patients developed acute Gr 2 GI toxicity, and 1 patient developed acute Gr 3 diarrhea and proctitis. This patient had asymptomatic Crohn's disease prior to IMRT, not on medication, and was treated to the prostate and pelvic nodes. Late Gr 1 GI toxicity was seen in 4 (22%) patients. Median time to late GI toxicity was 9.5 months. No patients developed late Gr 2 or higher GI toxicity.

CONCLUSION

Modern radiation techniques including IMRT and PT are well tolerated in PC patients with well-controlled IBD. Larger studies with longer follow up would be helpful to further characterize these patients' outcomes. In the meantime, IMRT and PT should be considered as treatment options in patients with well-controlled IBD.

Intensity-Modulated Neutron Therapy (IMNT) for Head and Neck Cancer: Early Toxicity Outcomes

PURPOSE/OBJECTIVE(S)

Locally advanced head & neck cancers (HNC) are challenging to treat due to abutment of critical, dose-limiting structures. Fast neutron radiotherapy (NT) is a high linear energy transfer (LET) modality that provides better local control than photons for radioresistant cancers such as salivary gland tumors, but there have been concerns of toxicity with 3D conformal neutron therapy in the past. Recent technological advances have enabled the planning and delivery of IMNT, which improves target conformality and may reduce toxicity compared to 3D conformal NT. We report the first clinical evaluation of early toxicity outcomes of IMNT for HNC.

MATERIALS/METHODS

Study is a single-institution retrospective review of all HNC patients treated with curative-intent IMNT from 10/2022 to 2/2023, using a hospital-based cyclotron (50.5 MeV 1H+ beam incident on a Be target) equipped with an isocentric gantry and multileaf collimator (MLC). A commercial treatment planning system with custom neutron-specific scattering kernels was used for IMNT planning using 4-6 fields. Patient-specific quality assurance included ionization chamber measurements and a novel 12C(n,2n)11C positron emission portal imaging system. kV portal imaging was used to confirm patient setup prior to each treatment session. All patients were prescribed 18.4 Gy at 1.15 Gy/fraction, delivered 4 days/week, which is equivalent to an x-ray EQD2 of approximately 70 Gy (RBE ∼ 3.8). Clinical observations suggest the RBE for radioresistant HNC may be as large as 8. Patients underwent weekly toxicity assessment, and acute toxicities were graded (G) by CTCAE v5.0.

RESULTS

Ten patients received IMNT, median age 61 (range 34-78). Primary tumor sites were base of tongue (n = 3), sinonasal (n = 3), parotid (n = 2), submandibular (n = 1), larynx (n = 1). Tumor histologies included adenoid cystic carcinoma (n = 7), other salivary gland carcinomas (n = 2) and mucosal melanoma (n = 1). Most had T4 disease (n = 8) and one had N3b disease. Six had surgical resection with high-risk features, and 6 had gross measurable disease prior to IMNT. None had concurrent systemic therapy. Uninvolved salivary glands were spared in most patients. All patients completed treatment. Median follow up was 22 days (0-48). Acute toxicities (n, G 1, 2, 3) included skin (8, 3, 0), dysgeusia (1, 6, 0), xerostomia (3, 5, 0), mucositis (2, 0, 5), nausea (3, 0, 1). One patient had >10% weight loss and brief admission for supportive care and PEG placement; one patient had prophylactic PEG; both regained oral independence during follow-up. There was no Grade 4+ toxicity.

CONCLUSION

IMNT improves the therapeutic ratio compared to 3D conformal NT and expands indications for NT in patients with radiorefractory tumors. Acute toxicity compares favorably with photons. Longer clinical and toxicity follow-up is anticipated. A prospective trial is planned to evaluate quality of life measures.

[Applying Multiple Strategies to Enhance the Completion Rate of Critical Care in COVID-19 Patients]

BACKGROUND & PROBLEMS

Taiwan entered the community transmission stage of COVID-19 in May 2021, with numbers of locally confirmed cases and critical cases increasing sharply. Medical institutions deployed special units to treat patients. In our hospital, a special COVID-19 intensive care units staffed with nursing personnel across various specialties was established. The rate of COVID-19 critical care completion among nurses in this unit was 79.1%. The reasons for non-completion were found to include limited intensive care standards for COVID-19; inadequate training, teaching aids, and practice manuals; and the overwhelming amount of new COVID-19-related information and updates.

PURPOSE

The aim of this project was to increase the team's COVID-19 critical care completion rate from 79.1% to 93.5%.

RESOLUTIONS

Multiple strategies were implemented, including: (1) providing online education and training, (2) establishing a platform for sharing COVID-19-related updates, (3) creating a QR-code accessible COVID-19 reference database, (4) creating a COVID-19 practice manual, and (5) providing simulation training sessions on wearing personal protective equipment during critical care.

RESULTS

The critical-care completion rate for patients with COVID-19 infection increased significantly in this unit from 79.1% to 98.2%, which exceeded the project goal.

CONCLUSIONS

Implementing a multi-strategy intervention that includes both online and simulation training may be effective in improving the critical care completion rate for patients with COVID-19 infection.

The impact and distinction of 'lipid healthy but obese' and 'lipid abnormal but not obese' phenotypes on lumbar disc degeneration in Chinese

Background

Lipid abnormality and obesity have been proposed to be associated with lumbar disc degeneration, but little is known about the effect of ‘lipid healthy but obese’ (LH-O) and ‘lipid abnormal but not obese’ (LA-NO) phenotypes on lumbar disc degeneration in Chinese. The study aims to determine the impact and distinction of LH-O and LA-NO phenotypes on lumbar disc degeneration in Chinese, and to identify the association of related factors with risk of lumbar disc degeneration.

Methods

A total of 678 individuals were included with lumbar magnetic resonance imaging, serum lipid levels and anthropometric measurements. Obesity was defined on the basis of body mass index or waist to hip ratio (WHR). Pfirrmann score and Weishaupt’s scale were utilized to assess the degree of disc degeneration and facet joint degeneration.

Results

The incidence of the LH-O and LA-NO phenotypes were 11.4% and 18.1%, respectively. LA-NO phenotype demonstrates a high incidence for disc degeneration (P < 0.05), while LH-O phenotype confers a severe disc degeneration grade (P < 0.05). No statistical difference in the percentage of severe facet joint degeneration grade in each group (P > 0.05). Elevated triglycerides and greater WHR may be the risk factors for lumbar disc degeneration in Chinese.

Conclusion

LH-O and LA-NO phenotypes are common with different status of disc degeneration in Chinese. Elevated triglycerides and abdominal obesity appear to play crucial roles in the development of lumbar disc degeneration.

Effects of SCH23390 and raclopride on a run-climb-run behavioral task in rats

The present study was designed to compare the putative differential behavioral consequences of treatment with SCH23390 (a selective dopamine D1 receptor blocker) and raclopride (a selective dopamine D2 receptor blocker) by employing a run-climb-run (RCR) behavioral task of different lengths. Rats were trained to traverse an uncovered floor alleyway (150 cm), climb a vertical rope (70 or 130 cm), and run across an upper board (100 cm) to access water for the reinforcement. At doses of 0.05, 0.10 and 0.15 mg/kg administered intraperitoneally 60 min before the behavioral session, both SCH23390 and raclopride significantly increased the total time to complete the tasks in a dose-related fashion. Microstructural analysis on the RCR behavioral performance revealed that the most apparent impairment induced by either drug was observed as the subject shifted motion from the end of the floor alleyway to the rope when hopping or to initiate climbing. However, the motion shift from climbing to running on the upper board was significantly impaired by raclopride, but not by SCH23390. Surprisingly, neither SCH23390 nor raclopride affected the climbing response itself. Running responses on the floor alleyway board were significantly disrupted by raclopride, whereas those on the upper board were significantly disrupted by SCH23390. Deficits induced by both drugs were more profound for the longer compared to the shorter rope, and were most notably shown at the transition area from running to climbing. These data indicate that both dopamine D1 and D2 receptors are involved in the RCR behavior performance. The results also suggest that the cost of motoric demand for behavioral performance is important for evaluating of the effects of drugs blocking dopamine receptors.

Qualifying ELISA data: combining information

With immunoassay or bioassay data, the assay standards often exhibit considerable inter-assay variability. However, the assay controls, which are used to monitor the assay performance and set acceptance criteria, should have no or less interassay variability. In this paper, we develop a mixed-effect calibration model for the assay controls to set new acceptance criteria and qualify the enzyme-linked immunosorbent assay (ELISA) data, which incorporates the interassay variation of assay standards and the nature of the assay controls, and overcomes the problems caused by traditional fixed-effect calibration model.

Capillary electrophoretic determination of apoptosis of HeLa cells induced by trichosanthin

Apoptosis is a distinct mode of cell death that is responsible for deletion of cells in normal tissues; it also occurs in specific pathologic contexts. The observation of apoptosis is very important in the research of cancer and cancer therapy. The traditional observation method of apoptosis was agarose gel electrophoresis, which is depending on the determination of ladder-liking DNA fragments extracted from apoptotic cells. It is time-consuming and low-sensitive. Recently, the sieving capillary electrophoresis has been used to detect apoptosis too. However, the problem of DNA fragments contamination is still existing. Here, we have developed a capillary electrophoresis method that could detect apoptosis of whole cell directly and do not need to extract DNA fragments from cells. Apoptosis of adherent cell HeLa cell of carcinoma induced by cyclophosphamide was used as the model to establish the method. The effluence of medicine concentration on apoptosis of cells was studied in detail. It was also found that the method could detect the change of cells in the early period of apoptosis. The induction of apoptosis of HeLa cell by trichosanthin was determined with the method, and the result of flow cytometry was also proved that trichosanthin could result in apoptosis of HeLa cells.

A note on concordance correlation coefficient

In this note, we first review some recent developments about measures of agreement, which are often required in medicine and other sciences, with focus on differences between these methods. In the last part, we mention five important concerns when using a newly developed concordance correlation coefficient. Our conclusion is that we need to be especially careful when using existing correlation methods and a new correlation method needs to be developed in the future.

Reoperation for recurrent trigeminal neuralgia after microvascular decompression

BACKGROUND

Microvascular decompression (MVD) is an effective technique for those who have trigeminal neuralgia (TN) but cannot tolerate, or show no response to medicine. Though the initial success rate is high, some patients may develop severe recurrent neuralgia, especially after a longer period of follow-up. The efficacy of reoperation needs to be evaluated. To know the possible risk factors of recurrence after initial MVD is mandatory to the management of recurrent TN.

METHODS

Among the 80 cases of TN treated with MVD, five cases showed severe recurrent symptoms within a follow-up period from 9 months-4 years. The symptoms recurred on the same side of the face, and were unresponsive to medical treatment. Brain computed tomography (CT) and magnetic resonance imaging (MRI) may reveal the etiology of recurrence. Repeat decompression of the trigeminal nerve was the main goal of reoperation, which was done via a suboccipital approach.

RESULTS

Over the past 17 years, 80 MVDs for TN have been performed at Chang Gung Memorial Hospital. There were five cases of serious postoperative recurrence, which could not be relieved by medicine. Recurrence occurred 1 day-12 months after the initial surgery. Three cases were due to vascular compression, while two were caused by the local effect of Teflon felt. Reoperation produced complete remission in four patients, and partial remission in one.

CONCLUSIONS

An increasing number of patients may experience severe recurrent TN after initial MVD during a long period of follow-up. Reoperation is safe and beneficial for these patients, but the results are dependent on the etiology of the recurrence. Further vascular compression of the trigeminal nerve can be relieved by MVD. Otherwise, in cases of severe adhesion caused by Teflon, complete microneural lysis can achieve satisfactory results.

A canine model of acute hindbrain ischemia and reperfusion

Animal models of brain stem ischemia are needed for pathophysiological study and evaluation of treatment; few such models are available currently. A new canine model of hindbrain ischemia and reperfusion is introduced in this article. Through an anterior cervical approach, the basilar artery was surgically exposed in 18 dogs. The posterior communicating and superior cerebellar arteries were embolized with cyanoacrylate glue to isolate the posterior circulation from the anterior circulation. Reversible hindbrain ischemia was induced in 14 dogs by the temporary clipping of the vertebral and ventral spinal arteries for various periods (10-30 min), then the clips were removed and reperfusion was achieved for 5 hours. In all 14 dogs, the hindbrain ischemia was confirmed by the decreased perfusion pressure in the basilar artery (< 10 mm Hg), the diminished regional cerebral blood flow as measured with a laser Doppler flowmeter at the medulla oblongata (< 10 ml/100 g/min), the flattened brain stem auditory evoked potentials, and the increased leakage of Evans blue dye from tissue. These parameters did not change in the four control dogs. The changes in brain stem auditory evoked potentials were closely related to the length of ischemic interval; after 10 minutes of ischemia, reperfusion fully reversed the changes in brain stem auditory evoked potentials, but 20-minute and 30-minute ischemic intervals partially or totally depleted the brain stem auditory evoked potentials. Delayed postischemic hypoperfusion occurred in all five dogs that underwent the 30-minute ischemic interval. The early physiological changes in this model allowed us to estimate the severity of brain stem ischemia and the resulting damage.(ABSTRACT TRUNCATED AT 250 WORDS)

Postictal neurogenic pulmonary edema during uncal herniation--a case report and literature review

A 13-year-old boy fell off a tree and developed an acute subdural hematoma (SDH) which was treated conservatively because the patient was fully conscious. After a generalized tonic-clonic seizure, he manifested signs of uncal herniation and neurogenic pulmonary edema (NPE). The patient made a good recovery after craniotomy and evacuation of the SDH with intensive pulmonary care. Though rare, uncomplicated postictal NPE in children almost runs a smooth course with favorable outcomes. However, the mortality rate is high in postictal NPE complicating cerebral herniation, and it seems an exception that our patient made a good recovery.

Serial regional blood flow and visual evoked responses in transient cortical blindness

Normal regional blood flow was documented by Single Photon Emission Computed Tomograms 5 and 20 hours before the full recovery of cortical blindness in two patients, lending itself to the possibility of being a prognostic factor. Rubbing of the posterior cerebral arteries against the tentorial edges during trauma instead of traction was believed to cause blindness in one patient and embolization due to hammering bone grafts home during cervical spinal fusion, in the other. Pattern reversal visual evoked responses (PRVERs) were absent during blindness; upon recovery P 100 with full amplitude and normal latency appeared despite the presence of tunnel vision. These are consistent with the fact that the central 8-10 degrees of visual field represented in the posterior occipital poles being the main sources of P 100 in association with the x-cells in the centre of the retina.

Inhibition of some human neutrophil functions by the cyclooxygenase inhibitor ketorolac tromethamine

Ketorolac tromethamine, a new nonsteroidal anti-inflammatory agent of the pyrrolo-pyrrole group, was assayed for inhibitory effects on polymorphonuclear leukocytes (PMN) in a variety of systems. Ketorolac inhibited PMN superoxide anion generation, lysozyme release, myeloperoxidase release, adherence to plastic surfaces, and chemotaxis in response to N-formyl-methionyl-leucyl-phenylalanine (fMLP) in a dose-dependent manner. Ketorolac also inhibited phorbol myristate acetate-stimulated adherence of PMN to bovine pulmonary artery endothelial cells. The drug inhibited lysozyme and myeloperoxidase release by PMN in response to C5a but failed to inhibit C5a stimulation of PMN in any of the other assays. Levels of ketorolac required to inhibit PMN function in most systems were in the range of 0.2 to 1.0 mg/ml, but chemotaxis to fMLP was inhibited by concentrations of ketorolac as low as 1 microgram/ml. Ketorolac, currently the only nonsteroidal anti-inflammatory drug available in a parenteral form may have therapeutic usefulness in a variety of conditions thought to be mediated in part by PMN, including sepsis.