The transradial approach for selective carotid and vertebral angiography

PURPOSE

The transradial approach is not so popular in cerebral angiography. The purpose of this study was therefore to present our experience of success rate and safety of this method.

MATERIAL AND METHODS

From December 1998 to June 2001, 526 carotid and vertebral angiographies with DSA were performed via the radial artery. A 1.4-mm catheter was used through a 1.4-mm introducer sheath. We evaluated the procedure as successful if sufficient images for diagnosis were obtained of the bilateral carotid arteries and unilateral vertebral artery. Each patient was reassessed for any complications, occurring until the next morning. The length of time needed for an examination was measured in the last 10 cases.

RESULTS

In all but 5 cases, the procedures were evaluated as successful (99.0%). Unsuccessful cases manifested severe pain at the radial puncture, angiospasm at the radial artery, loop formation at the radial artery, occlusion at the subclavian artery, and an aberrant right subclavian artery. No severe complications including neurological ones were encountered. Minor complications were noted in 17 cases (3.2%): 4 cases of thrombus at the ulnar artery, 1 angiospasm at the radial artery, and 12 cases of small hematoma at the puncture site. The radial approach took 14 min less in the common carotid study and 3 min 30 s less in the internal carotid study than by the femoral approach.

CONCLUSION

The transradial approach enabled selective studies for carotid and vertebral angiography with a high success rate and safety with few complications.

The transradial approach for selective carotid and vertebral angiography

PURPOSE

The transradial approach is not so popular in cerebral angiography. The purpose of this study was therefore to present our experience of success rate and safety of this method.

MATERIAL AND METHODS

From December 1998 to June 2001, 526 carotid and vertebral angiographies with DSA were performed via the radial artery. A 1.4-mm catheter was used through a 1.4-mm introducer sheath. We evaluated the procedure as successful if sufficient images for diagnosis were obtained of the bilateral carotid arteries and unilateral vertebral artery. Each patient was reassessed for any complications, occurring until the next morning. The length of time needed for an examination was measured in the last 10 cases.

RESULTS

In all but 5 cases, the procedures were evaluated as successful (99.0%). Unsuccessful cases manifested severe pain at the radial puncture, angiospasm at the radial artery, loop formation at the radial artery, occlusion at the subclavian artery, and an aberrant right subclavian artery. No severe complications including neurological ones were encountered. Minor complications were noted in 17 cases (3.2%): 4 cases of thrombus at the ulnar artery, 1 angiospasm at the radial artery, and 12 cases of small hematoma at the puncture site. The radial approach took 14 min less in the common carotid study and 3 min 30 s less in the internal carotid study than by the femoral approach.

CONCLUSION

The transradial approach enabled selective studies for carotid and vertebral angiography with a high success rate and safety with few complications.

Oxidized low density lipoprotein (Ox-LDL) as a marker of atherosclerosis in hemodialysis (HD) patients

AIM

To characterize the relationship between oxidative stress and atherosclerosis in HD patients.

METHODS

Seventy-five HD patients were entered into the study. Ox-LDL was measured as a probe for peroxidation and compared to clinical atherosclerotic parameters. Prospective studies were also performed to assess the effects of vitamin E-bonded membrane on oxidative stress.

RESULTS

Elderly patients tended to show elevated Ox-LDL (alpha = 0.060+/-0.021 ng/microg LDL protein/year, r = 0.35, p < 0.05). Levels of Ox-LDL in the patients with positive history for atherosclerotic diseases (3.1+/-0.4 ng/microg LDL protein, n = 36) were higher than those with a negative history (1.6+/-0.2, n = 39, p < 0.01). Further-more, ankle/brachial pressure index was negatively correlated to Ox-LDL (alpha = -0.052+/-0.012/ng/microg LDL protein, r = 0.42, p < 0.01). Application of vitamin E-bonded membrane for 10 months (-38+/-11%, n = 14, p < 0.05), but not synthetic membrane, ameliorated Ox-LDL.

CONCLUSIONS

Our results indicate that Ox-LDL is elevated in aged HD patients. In addition, the present data provide evidence that vitamin E-bonded dialyzers attenuate oxidative stress. Finally, our findings suggest that Ox-LDL correlates to the magnitude of peripheral arterial diseases in HD patients.

Palmaz stent deployment for subclavian and brachiocephalic arterial occlusive disease. Factors predictive of restenosis

SUMMARY

Palmaz stent deployment is a useful method for subclavian and brachiocephalic arterial occlusive disease. We evaluated restenosis or intimal thickening after Palmaz stent deployment for nine lesions of subclavian or brachiocephalic arterial occlusive disease focusing on stent diameter, atheroma thickness near the stent, and degree of coverage for the lesion. Follow up DSA and IVUS at 5-14 months (mean 9) after therapy showed no significant changes in the size or shape of the stent itself There were two lesions of thin in-stent intimal hyperplasia and five lesions of thick hyperplasia. There was no close relationship between intimal hyperplasia and stent diameter or atheroma size (relative thickness). There was some relationship between the degree of coverage of the lesion by the stent and degree of intimal hyperplasia, but to determine statistical significance, accumulation of a greater number of cases is necessary.

[Efficacy of bispectral index for anesthetic management of combined off-pump coronary artery bypass grafting and abdominal aortic aneurysm replacement]

A 57-year-old female patient underwent combined off-pump coronary artery bypass grafting and abdominal aortic aneurysm replacement. Anesthesia was maintained with propofol, fentanyl, and thoracic epidural anesthesia. Propofol doses were adjusted to maintain bispectral index (BIS) between 40-60. Despite the remarkable hemodynamic changes, BIS remained stable at about 50 during the surgery. The average dose of propofol was 3.3 mg.kg-1.hr-1. The patient awoke an hour after the surgery and was extubated 1.5 hours thereafter. This case report suggests that BIS is a useful index to determine the depth of anesthesia during surgeries which induce marked hemodynamic changes.

[Effects of volume and concentration of lidocaine on epidural anesthesia]

We studied 40 patients scheduled for gynecological surgery to evaluate the effects of volume and concentration of lidocaine on epidural anesthesia. We injected lidocaine 300 mg as 1% (30 ml) or 2% (15 ml) through epidural catheter at L 1/2. There was no significant difference in the spread of sensory blockade (cold and pain) and the Bromage scale between the two lidocaine solutions. This result suggests that volume and concentration of lidocaine do not affect the effects of epidural anesthesia.

Analysis of the enhancement of backscattering by nonspherical particles with flat surfaces

We examine backscattering by analyzing large nonspherical particles with flat surfaces for which where the size is much larger than the wavelength, using ray optics and diffraction theory. We show that the backscattering cross section for rectangles can be 1 order of magnitude larger than that for spheres with same geometrical cross sections, depending on the orientation of the particles. Then we show that there is a difficulty in estimating the backscattering cross section for hexagonal columns with the available solutions but that it is possible to estimate the integration of the differential scattering cross section over small solid angles in backward directions. The integral values for hexagonal columns are found to be more than 1 order of magnitude larger than that for spheres with the same volume. As an application, the use of power from hexagonal columns for lidar observations is analyzed. Unlike for spherical particles with their dependence on Z(-2) (where Z is the distance between the particle and the detector), for nonspherical particles such dependence varies with the particles' nonsphericity, such as shape and orientation: Z(0) for a hexagonal plate randomly oriented in the horizontal plane; Z(-1) for a hexagonal column randomly oriented in the horizontal plane.

[The effect of lidocaine on the bispectral index during anesthesia induction with propofol]

We investigated the effect of premixing lidocaine with propofol on a bispectral index (BIS) during propofol infusion. We studied 40 adult patients given mixture of 1% propofol 20 ml with 2 ml of normal saline (control group) or 2% lidocaine (lidocaine group) infused at 2 ml.kg-1.hr-1 for 10 minutes. Heart rate, mean arterial pressure, and BIS were measured every minute. The addition of lidocaine to propofol reduced the incidence of injection pain from 85% to 10% but did not change the induction time. Propofol significantly decreased mean arterial pressure and BIS but there was no difference between the groups. In conclusion, premixing lidocaine with propofol reduces injection pain without affecting the hypnotic effect.

Detection of early venous filling in gliomas on MRI: preliminary study by 2D time-resolved dynamic contrast-enhanced MR angiography with echo-sharing technique

We evaluated the detection of early venous filling of gliomas by 2D time resolved dynamic contrast enhanced MR digital subtraction angiography (MR-DSA) with echo-sharing technique and compared the results with those of conventional contrast digital subtraction angiography (C-DSA). C-DSA and MR-DSA examinations were performed in eight patients with malignant gliomas and compared with regard to the visualization of early filling veins; time intensity curves of arteries, early filling veins and normal veins were made, and rise time and time to peak were evaluated. MR-DSA visualized 12 out of 17 early filling veins depicted on C-DSA. The failure of five veins to be depicted may be due to the overlapping of other structures, such as other vessels and tumor stain. On time intensity curves, the mean difference in rise time was 0.9 sec between the artery and early filling vein, and the mean difference of time to peak was 1.6 sec. C-DSA has been the modality of choice in demonstrating early venous filling, a useful finding in the differential diagnosis of gliomas. However the high temporal resolution of MR-DSA with echo-sharing technique provides sufficient visualization of early venous filling of gliomas. Additional information for precise differential diagnosis may be obtained by adding MR-DSA to the imaging protocol for gliomas.

Effects of ethanol on L-arginine transport in rat Ito cells in relation to nitric oxide production

BACKGROUND

Nitric oxide (NO) is a potent mediator of hepatic sinusoidal hemodynamics that is synthesized in the hepatic stellate cells (Ito cells, fat-storing cells) and affects these cells. NO production may depend on the induction of inducible nitric oxide synthase and on transport of extracellular L-arginine. The precise mechanism that controls NO production in stellate cells was characterized recently.

METHODS

Kinetic analysis of L-arginine transport and reverse transcription-polymerase chain reaction for cationic amino acid transporter (CAT) were carried out by using stellate cells prepared from the male Wistar rat. The effect of ethanol on L-arginine transport and NO production of stellate cells was assessed in the presence of tumor necrosis factor (TNF)-alpha and interferon (IFN)-gamma.

RESULTS

The L-arginine transport system functioning in the hepatic stellate cells was system y+, possibly mediated by CAT-1 and CAT-2B (Km approximately 50 microM). IFN-gamma in combination with TNF-alpha induced NO production with an enhancement in CAT-2B mRNA expression and L-arginine transport, whereas L-arginine transport and NO production were suppressed by coincubated ethanol.

CONCLUSIONS

In hepatic stellate cells, ethanol has suppressive effects on NO production and extracellular L-arginine transport in the presence of TNF-alpha and IFN-gamma. The estimated Km of L-arginine transporter in hepatic stellate cells is very similar to the physiological L-arginine concentration in portal vein. Our findings may support the merit of further studies on the modulation of NO production via access to portal blood L-arginine concentration to control disturbed hepatic sinusoidal blood flow in patients with alcoholic liver disease.

Developmental regulation of transmitter release at the calyx of Held in rat auditory brainstem

1. Postnatal development of synaptic efficacy was studied at a single glutamatergic synapse formed by the calyx of Held in the rat brainstem. Throughout postnatal development from day 7 (P7) to day 14 (P14), both the excitatory postsynaptic currents (EPSCs) evoked at a basal frequency (0.05 Hz) and spontaneous miniature EPSCs (mEPSCs) remained similar in their mean amplitudes, but became faster in their decay times. 2. During repetitive stimulation at 1-100 Hz, EPSCs underwent a depression. The magnitude of the depression significantly decreased from P7 to P14, whereas the time course of recovery from depression (after 10 Hz stimulation) remained similar throughout development. 3. The size of the readily releasable pool (RRP) of synaptic vesicles (N) and the release probability (p) were estimated from the cumulative amplitude histogram of EPSCs during high frequency stimulation. From P7 to P14, N increased 2-fold, whereas p decreased to a similar extent. 4. The open channel blocker MK-801 caused an activity-dependent attenuation of NMDA receptor-mediated EPSCs. The blocking rate became slower from P7 to P14, further supporting the developmental decrease in p. 5. Given that the mean amplitudes of mEPSCs (q) and evoked EPSCs (Npq) remain constant throughout the developmental period, these results suggest that a developmental increase in N compensates for a concomitant decrease in p. We conclude that the developmental decrease in the release probability will establish a stable synapse at which only a small fraction of releasable synaptic vesicles is depleted during high frequency transmission.

Development of "Standards for the Evaluation of Hospital Infection Control Policies and Procedures, the Second Version"

The Japan Society for Quality in Health Care (JSQua) created "Standards for the Evaluation of Hospital Infection Control Policies and Procedures, the First Version" in 1998 and carried out third-party surveys. Through the experience of those surveys, we revised the standards and created a second version in 1999. The surveyors felt that in using the second version of the standards it would be easier to evaluate the quality of hospital care and that these standards would be more widely applied.

Effects of ethanol on L-arginine transport in rat Ito cells in relation to nitric oxide production

BACKGROUND

Nitric oxide (NO) is a potent mediator of hepatic sinusoidal hemodynamics that is synthesized in the hepatic stellate cells (Ito cells, fat-storing cells) and affects these cells. NO production may depend on the induction of inducible nitric oxide synthase and on transport of extracellular L-arginine. The precise mechanism that controls NO production in stellate cells was characterized recently.

METHODS

Kinetic analysis of L-arginine transport and reverse transcription-polymerase chain reaction for cationic amino acid transporter (CAT) were carried out by using stellate cells prepared from the male Wistar rat. The effect of ethanol on L-arginine transport and NO production of stellate cells was assessed in the presence of tumor necrosis factor (TNF)-alpha and interferon (IFN)-gamma.

RESULTS

The L-arginine transport system functioning in the hepatic stellate cells was system y+, possibly mediated by CAT-1 and CAT-2B (Km approximately 50 microM). IFN-gamma in combination with TNF-alpha induced NO production with an enhancement in CAT-2B mRNA expression and L-arginine transport, whereas L-arginine transport and NO production were suppressed by coincubated ethanol.

CONCLUSIONS

In hepatic stellate cells, ethanol has suppressive effects on NO production and extracellular L-arginine transport in the presence of TNF-alpha and IFN-gamma. The estimated Km of L-arginine transporter in hepatic stellate cells is very similar to the physiological L-arginine concentration in portal vein. Our findings may support the merit of further studies on the modulation of NO production via access to portal blood L-arginine concentration to control disturbed hepatic sinusoidal blood flow in patients with alcoholic liver disease.

Long-term audiological feature in Pendred syndrome caused by PDS mutation

Pendred syndrome is an autosomal recessive disorder characterized by profound deafness in childhood and goiter. We report a case of Pendred syndrome in a 27-year-old woman who had a diffuse goiter and progressive sensorineural hearing loss with fluctuation and a missense mutation (His723Arg) in the PDS gene identified in a homozygous state. Audiological findings were observed clinically over a 20-year period. Progressive hearing loss with fluctuation occurred before age 12 years. An enlarged vestibular aqueduct with enlargement of the endolymphatic duct and sac was confirmed with 3-dimensional magnetic resonance imaging hydrography.

Polyamine cytotoxicity in the presence of bovine serum amine oxidase

The toxicity of extracellular spermine, determined in the presence of fetal calf serum, was studied using three cell lines: FM3A, L1210, and NIH3T3 cells. Amine oxidase in fetal calf serum produces aminodialdehyde generating acrolein spontaneously, H(2)O(2), and ammonia from spermine. Spermine toxicity was prevented by aldehyde dehydrogenase, but not by catalase. Similar concentrations of spermine and acrolein were needed to produce toxicity. Other aldehydes (formaldehyde, acetaldehyde, and propionaldehyde) and hydrogen peroxide were less toxic than acrolein. Spermidine and 3-aminopropanal, which produces acrolein, also exhibited severe cytotoxicity. The degree of cytotoxicity of spermine, spermidine, and 3-aminopropanal was nearly parallel with the amount of acrolein produced from each compound. Thus, it was deduced that acrolein is a major toxic compound produced from polyamines (spermine and spermidine) by amine oxidase.

Role of nitric oxide in focal microcirculation disorder of guinea pig cochlea

This study was designed to evaluate the role of endogenous nitric oxide (NO) in focal microcirculation disorder of the guinea pig cochlea. Focal microcirculation disorder was induced by a photochemical reaction at the lateral wall of the second cochlear turn. Saline or N omega-nitro-L-arginine methyl ester (L-NAME) was administered before the onset of photochemical reaction. Cochlear blood flow (CBF) was measured at the focal lesion (ischemic core), 1 mm from the lesion in the apical and basal direction (ischemic border zone) by using a novel non-contact laser blood flowmeter. NO synthase activities were measured by radioenzymeassay. In the saline pretreatment group, CBF was significantly decreased to 58.8+/-4.4% of the baseline at the ischemic core 30 min after the onset of photochemical reaction (P<0.01), while CBF showed no significant change at the ischemic border zone. In the L-NAME pretreatment group, CBF was significantly decreased not only at the focal lesion (48.3+/-6.5%, P<0.01), but also at the ischemic border zone (apical, 49.3+/-2.3%, P<0.05; basal, 58.7+/-7.1%, P<0.05, respectively). NO synthase III activity of cochlea was increased significantly (P<0.01) 15 min after microcirculation disorder. These findings suggest that formation of endogenous NO plays a key role in the maintenance of CBF in acute focal cochlear microcirculation disorder.

Reversible nephrotic syndrome in a patient with amyloid A amyloidosis of the kidney following methicillin-resistant Staphylococcus aureus infection

A common form of methicillin-resistant Staphylococcus aureus (MRSA) associated glomerulonephritis is either an endocapillary proliferative glomerulonephritis or a crescentic glomerulonephritis. This report describes the development of reversible nephrotic syndrome following MRSA infection in a patient with amyloid A amyloidosis. The patient had been diagnosed as having rheumatoid arthritis for 50 years. Suppurative arthritis due to MRSA became complicated 2 years prior to admission to our hospital. In the meantime, a nonnephrotic-range proteinuria developed. Two weeks before admission, nephrotic syndrome developed. The serum creatinine level remained unchanged throughout the course, but common features characteristic of MRSA-associated glomerulonephritis were observed in this patient, such as elevated serum IgG and IgA levels. A renal biopsy specimen showed glomerular amyloid A amyloidosis of a nodular type, infiltrated mononuclear cells in the mesangium, deposition of IgG, IgA, and C3, and swelling of glomerular endothelial cells. There were no crescentic glomeruli. Following surgical eradication of the MRSA focus in the right knee joint, nephrotic syndrome disappeared. Hence, it was highly possible that MRSA infection induced a reversible nephrotic syndrome by causing reversible injuries to glomerular endothelial cells. The description of this case serves to illustrate the range of MRSA infections that may cause various forms of glomerulonephritides.

Eosinophil-induced liver injury: an experimental model using IL-5 transgenic mice

BACKGROUND/AIMS

In certain liver diseases, activated eosinophils are considered to be important effector cells in addition to T-cell-mediated cytotoxicity. No experimental model, however, has been developed for in vivo analysis of the cytotoxic mechanisms.

METHODS

Interleukin-5 (IL-5) transgenic mice (C3H/HeN-TgN(IL-5)Imeg), which exhibit marked eosinophilia without liver injury, were injected once with 25 microg of lipopolysaccharide (LPS) intraperitoneally. The mice were sacrificed weekly and eosinophilic injuries were assessed microscopically. To clarify the role of Kupffer cells and tumor necrosis factor-alpha (TNF-alpha) in the liver injury, gadolinium chloride (GdCl3) and anti-TNF-alpha neutralizing antibody were administrated before the LPS injection.

RESULTS

Two weeks after injection, transgenic mice exhibited marked infiltration of eosinophils and extensive lobular necrosis. Transmigration of eosinophils through vascular endothelium and degranulation of eosinophil cytotoxic granules in inflamed areas were observed. These eosinophilic injuries were transient, but liver-specific. Pre-administration of GdCl3 and anti-TNF-alpha markedly reduced the hepatic inflammation, suggesting that LPS-activated Kupffer cells play a key role in producing the cytotoxicity of eosinophils by releasing TNF-alpha.

CONCLUSIONS

We have established an experimental model of eosinophil-induced liver injury using IL-5 transgenic mice. Since this model is simple and highly reproducible, it will be useful for analysis of in vivo cytotoxic mechanisms of eosinophils.

[Comparative survey of cardiac arrests during anesthesia and surgery in the 1980 s and 1999 s]

A survey of unexpected cardiac arrests, excluding those associated with cardiac surgery, that had occurred during anesthesia and surgery in the period 1980-1999 was conducted. There was no significant difference between the number of such cardiac arrests that occurred in the 1980 s (29/36,159, 0.080%) and the number in the 1990 s (33/37,643, 0.088%). According to the classification by Keenan et al., there were 3 cases (0.0083%) in the 80 s and 4 cases (0.0106%) in the 90 s that occurred due to anesthetic management. Cardiac arrests due to surgery itself significantly decreased from 21 cases in the 80 s to 6 cases in the 90 s, probably due to proper treatment for massive bleeding, a decrease in the number of cases of anaphylactic shock, and the development of novel anesthetics. Conversely, cardiac arrests due to preoperative conditions of the patients significantly increased from 5 cases in the 80 s to 23 cases in the 90 s. This increase seems to be due to an increase in the number of severe and multiple injuries and an increase in complicated major surgery. The increase in number of cases due to preoperative conditions also depends on coronary spasm and cardiac conduction insufficiency. Taking into consideration the improvement in intraoperative monitoring and the development of novel anesthetics in the 90 s, greater efforts should be made by anesthesiologists to reduce the incidence of cardiac arrest due to anesthetic management, and preoperative evaluation of surgical patients needs to be reconsidered.

Use of a wrist activity monitor for the measurement of nocturnal scratching in patients with atopic dermatitis

BACKGROUND

The amount of nocturnal scratching can be an indirect correlate of itch in pruritic dermatoses. We have previously used an infrared video camera to measure nocturnal scratching in atopic dermatitis (AD). Although this is a reliable method of measuring nocturnal scratching, it is not suitable for routine monitoring in clinical use.

OBJECTIVES

To find a simplified way of monitoring itch.

METHODS

We tried using a wrist activity monitor (ActiTrac) for the measurement of nocturnal scratching in patients with AD. ActiTrac is a wristwatch-shaped device that contains a piezoceramic sensor to measure and record limb movement over a pre-set time interval. The acceleration signal produced by motion of the hands is stored and downloaded into a personal computer. The average value of acceleration (AVA, 10(-3) g min(-1)) was calculated and compared with total scratching time as a percentage of total recording time (TST%) measured with the use of an infrared video camera in 63 recordings of 21 patients with AD. For 261 recordings in 29 patients with AD, the AVA was measured and correlated with disease severity, and compared with the AVA of five non-itchy controls.

RESULTS

There was a significant correlation between the AVA and TST% (r = 0.91, P < 0.001), and a regression equation of y = 0.44x - 2.5 was obtained. The AVA correlated well with the severity of AD and definitely differed from the results observed in normal controls. The AVA (mean +/- SD) was 44.4 +/- 19.1 for 115 recordings in patients with severe AD, 23.2 +/- 10.9 for 89 recordings in patients with moderate AD, 8.9 +/- 6.0 for 57 recordings in patients with mild AD and 4.1 +/- 1.9 for 25 recordings in five normal controls. The units used here are arbitrary units min-1 with a range of 0--250, which corresponds to 0-75 x 10(-6) g min(-1).

CONCLUSIONS

A wrist activity monitor is able to measure nocturnal scratching. However, further methods of analysis should be sought to select scratching activity exclusively.

Erythropoietin inhibits calcium-induced neurotransmitter release from clonal neuronal cells

Erythropoietin (EPO) and EPO receptor (EPO-R) are expressed in the brain but their neuronal functions are not yet clarified. The effects of EPO on neurosecretion were studied using clonal rat pheochromocytoma PC12 cells. EPO suppressed Ca(2+)-induced dopamine release from PC12 cells in a concentration- and time-dependent manner. Inhibition was also produced by an EPO mimetic peptide 1 (EMP1), a small synthetic peptide agonist of EPO-R, but not by its inactive analogue in which Cys residues were substituted with Ser. Inhibition was abolished by genistein but not by genistin. EPO and EMP1 induced autophosphorylation of Janus kinase 2 (JAK 2), a tyrosine kinase that associates with EPO-R, and dephosphorylation of GAP-43 in a tyrosine kinase-dependent fashion. These results suggest that EPO suppresses neurotransmitter release through activation of EPO-R linked to JAK2.

A new model for investigating hair cell degeneration in the guinea pig following damage of the stria vascularis using a photochemical reaction

We have established a new model for investigating the relationship between cochlear lateral wall damage and sensory cell degeneration in guinea pigs by using a photochemical reaction between the systemic injection of Rose Bengal (RB) and controlled green light irradiation to the cochlea. The photochemical reaction produced a reactive oxygen species, which then damaged the endothelium. This triggered platelet adhesion and aggregation at the site of endothelial injury to produce thrombi and affect microcirculation in the lateral wall at the site of irradiation. Changes were studied under a scanning electron microscope (SEM), and compound action potentials (CAP) were measured. SEM observations after tangential illumination of the cochlear wall revealed degeneration of the stria vascularis (SV). Specific morphological findings at 24 h included delayed degeneration of the outer hair cells concurrent with a significant increase in the CAP. Based on these findings, we suggest that degeneration of the SV was a direct result of the photochemical reaction, but CAP changes and sensory hair cell damage were secondarily caused by SV degeneration.