Discovery and quantification of a widespread methane ebullition event in a coastal inlet (Baltic Sea) using a novel sonar strategy

How much of the greenhouse gas methane is transported from the seafloor to the atmosphere is unclear. Here, we present data describing an extensive ebullition event that occurred in Eckernförde Bay, a shallow gas-hosting coastal inlet in the Baltic Sea, in the fall of 2014. A weak storm induced hydrostatic pressure fluctuations that in turn stimulated gas ebullition from the seabed. In a finely tuned sonar survey of the bay, we obtained a hydroacoustic dataset with exceptionally high sensitivity for bubble detection. This allowed us to identify 2849 bubble seeps rising within 28 h from the seafloor across the 90 km² study site. Based on our calculations, the estimated bubble-driven episodic methane flux from the seafloor across the bay is 1,900 μMol m⁻² d⁻¹. Our study demonstrates that storm-associated fluctuations of hydrostatic pressure induce bulk gas-driven ebullitions. Given the extensive occurrence of shallow gas-hosting sediments in coastal seas, similar ebullition events probably take place in many parts of the Western Baltic Sea. However, these are likely to be missed during field investigations, due to the lack of high-quality data acquisition during storms, such that atmospheric inputs of marine-derived methane will be highly underestimated.

Pharmacokinetics and Pharmacodynamics of Melagatran, a Novel Synthetic LMW Thrombin Inhibitor, in Patients with Acute DVT

Forty-eight patients with acute proximal deep vein thrombosis (DVT) were randomised to intravenous infusions for 4 to 6 days with melagatran, a novel synthetic low molecular weight thrombin inhibitor, or unfractionated heparin adjusted by the activated partial thromboplastin time (APTT). The aim of the study was to investigate the pharmacokinetics, pharmacodynamics and the safety of melagatran therapy at three different doses. Steady-state plasma concentrations were rapidly achieved and maintained throughout the infusion period. The mean plasma concentrations in the low, medium and high dose groups were 0.17, 0.31 and 0.53 μmol/l, respectively. The prolongation of APTT was stable during the melagatran infusions and correlated to the plasma concentration. Phlebographically verified regression of thrombus size measured as decrease in Marder score was seen after 4 to 6 days in 8 of 12 patients, 6 of 12 patients and 5 of 11 patients in the low, medium and high dose groups of melagatran and in 5 of the heparin-treated patients. In the low dose group with melagatran, thrombus extension was seen in one patient. At the dose levels studied, melagatran was well tolerated with no clinically significant bleeding problems, suggesting that melagatran could safely be given to patients suffering from DVT.

Value of high-resolution MR in patients scheduled for cochlear implantation

Objective: To determine sensitivity and specificity of high-resolution MR imaging and of high-resolution axial CT (HRCT) and to compare the two modalities in predicting the surgical and functional success of cochlear implantation.

Material and Methods: The presurgical MR images (2D T2W TSE, 3D T2*W CISS, plain and contrast-enhanced 3D T1W MP-RAGE) and axial HRCT findings of 26 patients were evaluated with regard to the predictive value concerning the success of cochlear implantation.

Results: We found a high correlation between MR and HRCT and the success of cochlear implantation. In all 26 patients, the MR-based predictions concerning the success of cochlear implantation were correct. In 10 patients, MR gave additional information to HRCT. In all patients, MR gave sufficient information about the status of the inner ear, inner auditory canal and cochlear nerve to aid the surgeon during the operation.

Conclusion: A high-resolution MR protocol consisting of coronal 2D T2W TSE, 3D T2*W axial CISS, plain and contrast-enhanced sagittal T1W 3D MP-RAGE is recommended for the evaluation of candidates scheduled for cochlear implantation. It provides information which cannot be obtained by HRCT.

Crystal structure analysis and extremely long-living light-induced metastable states in RbY[Fe(CN)5NO]2·10H2O and CsY[Fe(CN)5NO]2·10H2O

Crystal structures of both isostructural com-pounds were solved from single crystal X-ray diffraction data (space group P21/n; Z = 4; Rb-compound: a = 9.812(1) Å, b = 25.793(3) Å, c = 11.777(2) Å, β = 104.68(1)°, R gt(F) = 0.0458, wR ref(F 2) = 0.0918; Cs-compound: a = 9.9058(8) Å, b = 25.919(2) Å, c = 11.883(1) Å,β = 105.542(7)o, Rgt(F) = 0.0450,wRref(F2) = 0.0951. The main structural feature is the nitrosylpentacyanoferrate(II)-complex [Fe(CN)5NO]2–. The iron atoms are coordinated to five cyanide and one nitrosyl ligand. The coordination polyhedron of the Y3+ cation is a distorted tetragonal antiprism built up from three nitrogen atoms of three complexes and five water molecules. Both rubidium and cesium ions are surrounded by seven cyanide groups of five complexes and one water molecule to form a distorted bicapped trigonal prism. One metastable state (SI) can be excited by irradiation with light in the spectral range of 400–500 nm at temperatures below 180 K. The radiationless thermal decay is detected by Differential Scanning Calorimetry by heating above T = 180 K. Evaluating the exothermal heat flow using the Arrhenius law yields an activation energy of EA = 0.64(2) eV and a frequency factor of Z = 20(8)·1012s–1 for the rubidium compound and EA = 0.56(2) eV, Z = 30(8)·1010s–1 for the cesium compound. The contribution of the cations on the decay temperature of the metastable states is discussed on the basis of the atomic distances and coordinations.

Effects of digoxin on electrocardiogram in patients with acute atrial fibrillation--a randomized, placebo-controlled study. Digitalis in Acute Atrial Fibrillation (DAAF) Trial Group

BACKGROUND

Studies of healthy volunteers or patients in sinus rhythm have indicated that treatment with digoxin produces characteristic changes in the electrocardiogram (ECG). No randomized, placebo-controlled studies are available and no study has investigated the effect on ECG in patients with atrial fibrillation.

HYPOTHESIS

In a substudy to a trial comparing the therapeutic effect of intravenously administered digoxin with placebo in patients with acute atrial fibrillation, we investigated these effects as well as the relation between ECG changes and serum concentration of digoxin.

METHODS

In all, 167 patients were included. Standard ECGs recorded at baseline, and at 2, 6, 12, and 16 h after randomization were digitized, and changes in RR-intervals, QRS width, ST-segment amplitude at 60 ms after the J point, T-wave amplitude, and QTc interval were calculated. Furthermore, the correlation between the serum concentration of digoxin at 16 h after inclusion and changes on the ECG was analyzed.

RESULTS

Compared with placebo, digoxin resulted in an increase in RR-interval (p < 0.0001), a decrease in ST-segment and T-wave amplitude (p = 0.009 and p = 0.002, respectively), and in the QTc interval (p = 0.01). These changes were present 2 h after the first dose, but were more pronounced after 16 h. There was no significant correlation between serum concentration of digoxin and ECG changes at 16 h.

CONCLUSION

Compared with placebo, digoxin produces significant changes on ECG in patients with acute atrial fibrillation. The changes are in accordance with previous findings in individuals in sinus rhythm. There was no correlation between serum concentration of digoxin and ECG changes.

Symptoms of depression, prescription of benzodiazepines, and the risk of death in hemodialysis patients in Japan

Many hemodialysis patients in Japan have symptoms of depression, but whether those patients are treated appropriately is unknown. As part of the Dialysis Outcomes and Practice Patterns Study, data on symptoms of depression, physician-diagnosed depression, prescribed medications, and death were collected prospectively in cohorts in Japan (n=1603) and 11 other countries (n=5872). Symptoms of depression were as prevalent in Japan as elsewhere, but in Japan a much smaller percentage of patients had physician-diagnosed depression: only 2% in Japan vs 17% elsewhere. Antidepressants were much less commonly prescribed in Japan: only 1% in Japan vs 17% elsewhere for patients with many and frequent symptoms of depression, and 16% in Japan vs 34% elsewhere for patients with physician-diagnosed depression. In Japan, symptoms of depression were associated with prescription of benzodiazepines (without antidepressants), and patients with physician-diagnosed depression were twice as likely to be given benzodiazepines: 32% in Japan vs 16% elsewhere. Benzodiazepine monotherapy was associated with death (relative risk 1.56, 95% confidence interval (CI), 1.25-1.94), even after adjustments for 13 likely confounders (relative risk 1.27, 95% CI, 1.01-1.59). Hemodialysis patients in Japan with symptoms of depression are given not antidepressants but benzodiazepines, a practice associated with higher mortality.

Degenerative diseases of the lumbar spine. Comparison of the multiecho data image combination sequence with magnetization transfer saturation pulse versus lumbar myelography/postmyelographic computed tomography

PURPOSE

To compare a T2* weighted 2D spoiled gradient echo multiecho sequence (MEDIC) with magnetization transfer saturation pulse versus lumbar myelography and postmyelographic computed tomography (pCT).

MATERIAL AND METHODS

84 disk levels in 27 patients were examined. The vertebral bodies, intervertebral disks, neural foramina, cauda equina, ligamentum flavum, and narrowing of the spinal canal were investigated using an evaluation scale. In addition, the pCT and the MEDIC sequence were evaluated for assessing the narrowing of the neural foramina in a phantom study using a cadaver preparation of the lumbar spine.

RESULTS

A total of 28 disk herniations, 11 cases of osteophytes narrowing the spinal canal or the neural foramina, and 7 spinal canal stenoses were detected. The pCT was significantly better in visualizing the cauda equina. The MEDIC sequence was significantly superior in visualizing the extension of the ligamentum flavum. No statistical differences between either image modality were found concerning assessment of the narrowing of the neural foramina and the spinal canal, nor regarding evaluation of the vertebral disk and the vertebral body. Measurements of the phantom study showed that the MEDIC sequence did not overestimate narrowing of the neural foramina.

CONCLUSIONS

The T2* MEDIC sequence has proved to be as accurate as pCT in evaluating osteophytes and narrowing of the neural foramina. In doubtful standard magnetic resonance imaging findings, this means that an additional axial T2* MEDIC sequence may be of value in reaching the same accuracy as pCT.

Degenerative diseases of the cervical spine: comparison of a multiecho data image combination sequence with a magnetisation transfer saturation pulse and cervical myelography and CT

Assessing degenerative disease in the cervical spine remains a challenge. There is much controversy about imaging the cervical spine using MRI. Our aim in this prospective study was to compare a T2*-weighted 2D spoiled gradient-echo multiecho sequence (MEDIC) with a magnetisation transfer saturation pulse with cervical myelography and postmyelographic CT. Using an assessment scale we looked at the vertebral bodies, intervertebral discs, neural foramina, anterior and posterior nerve roots, grey matter, ligamentaflava, oedema in the spinal cord and stenosis of the spinal canal. We also evaluated postmyelography CT and the MEDIC sequence for assessing narrowing of the neural foramina in a cadaver cervical spine. We examined 67 disc levels in 18 patients, showing 18 disc prolapses and 21 osteophytes narrowing the spinal canal or the neural foramina. All MRI studies showed these abnormalities findings equally well. Postmyelography CT was significantly better for showing the bony structures and the anterior and posterior nerve roots. The MEDIC sequence provided excellent demonstration of soft-tissue structures such as the intervertebral disc and ligamentum flavum. No statistical differences between the imaging modalities were found in the assessment of narrowing of the neural foramina or the extent of spinal stenosis. The cadaver measurements showed no overestimation of abnormalities using the MEDIC sequence.

Clinical features and contemporary management of patients with low and preserved ejection fraction heart failure: baseline characteristics of patients in the Candesartan in Heart failure-Assessment of Reduction in Mortality and morbidity (CHARM) programme

AIMS

To describe the clinical characteristics and contemporary treatment of a broad spectrum of patients with chronic heart failure (CHF) randomised in the Candesartan in Heart failure-Assessment of Reduction in Mortality and morbidity (CHARM) programme, consisting of three component studies comparing placebo to candesartan.

METHODS AND RESULTS

CHARM Alternative, CHARM Added and CHARM Preserved enrolled 2028 low left ventricular ejection fraction (LVEF) ACE inhibitor intolerant patients, 2548 low LVEF ACE inhibitor treated patients and 3025 preserved LVEF patients, respectively. Patients in CHARM Preserved were more often female. The proportion of women in CHARM Preserved was 40% compared to 32% in CHARM Alternative and 21% in CHARM Added. Patients in CHARM Preserved were also more often hypertensive than in the other two trials (64% vs. 50% and 48%, respectively). Symptoms and signs (with the exception of a third heart sound) were similar in all three patient groups. Beta-blockers were used in over half of patients in all three groups. Digoxin and spironolactone were used less frequently and calcium antagonists more frequently in CHARM Preserved. Spironolactone was used most frequently in CHARM Alternative, i.e. in ACE inhibitor intolerant patients.

CONCLUSIONS

The CHARM Programme provides the largest and most detailed comparison to date of patients low- and preserved-LVEF CHF. It also describes the causes of ACE-inhibitor intolerance in a large cohort of patients and the other treatment which these patients receive.

MRI of the abnormal cervical spinal cord using 2D spoiled gradient echo multiecho sequence (MEDIC) with magnetization transfer saturation pulse. A T2* weighted feasibility study

OBJECTIVES

The aim of this study was to assess the potential of heavily T2* weighted 2D spoiled gradient echo multiecho sequence MEDIC (multi echo data image combination) with magnetization transfer saturation pulse (MTS) for detecting abnormality of the cervical spinal cord.

METHODS

11 patients, 5 women and 6 men aged from 14 to 79 years (mean age 51.18 years), with traumatic, hemolytic-hemorrhagic or neoplastic diseases of the cervical spinal cord were examined with MRI. In cases with suspected myelopathy, the feasibility of the 2D spoiled gradient echo multiecho sequence MEDIC with MTS was evaluated in comparison with the results of spin echo T1W, spin echo T2W, multi echo (TSE in our case) and spin-echo multi-echo technique with magnetization preparation (turbo inversion recovery--TIR--in our case) sequences.

RESULTS

Distortion of the "H" sign was found in all but one case. Hemorrhage was best shown by MEDIC, massive edema was very well visible using MEDIC, TIR and TSE T2W, whereas mild edema was visible with MEDIC only.

CONCLUSIONS

Our preliminary experience in 11 patients shows that MEDIC can be used for the diagnosis of cervical spinal cord pathology.

MR imaging of cranial nerve lesions using six different high-resolution T1- and T2(*)-weighted 3D and 2D sequences

PURPOSE

To find a suitable high-resolution MR protocol for the visualization of lesions of all 12 cranial nerves.

MATERIAL AND METHODS

Thirty-eight pathologically changed cranial nerves (17 patients) were studied with MR imaging at 1.5 T using 3D T2*-weighted CISS, T1-weighted 3D MP-RAGE (without and with i.v. contrast medium), T2-weighted 3D TSE, T2-weighted 2D TSE and T1-weighted fat saturation 2D TSE sequences. Visibility of the 38 lesions of the 12 cranial nerves in each sequence was evaluated by consensus of two radiologists using an evaluation scale from 1 (excellently visible) to 4 (not visible).

RESULTS

The 3D CISS sequence provided the best resolution of the cranial nerves and their lesions when surrounded by CSF. In nerves which were not surrounded by CSF, the 2D T1-weighted contrast-enhanced fat suppression technique was the best sequence.

CONCLUSIONS

A combination of 3D CISS, the 2D T1-weighted fat suppressed sequence and a 3D contrast-enhanced MP-RAGE proved to be the most useful sequence to visualize all lesions of the cranial nerves. For the determination of enhancement, an additional 3D MP-RAGE sequence without contrast medium is required. This sequence is also very sensitive for the detection of hemorrhage.

MR imaging of cranial nerve lesions using six different high-resolution T1- and T2(*)-weighted 3D and 2D sequences

PURPOSE

To find a suitable high-resolution MR protocol for the visualization of lesions of all 12 cranial nerves.

MATERIAL AND METHODS

Thirty-eight pathologically changed cranial nerves (17 patients) were studied with MR imaging at 1.5 T using 3D T2*-weighted CISS, T1-weighted 3D MP-RAGE (without and with i.v. contrast medium), T2-weighted 3D TSE, T2-weighted 2D TSE and T1-weighted fat saturation 2D TSE sequences. Visibility of the 38 lesions of the 12 cranial nerves in each sequence was evaluated by consensus of two radiologists using an evaluation scale from 1 (excellently visible) to 4 (not visible).

RESULTS

The 3D CISS sequence provided the best resolution of the cranial nerves and their lesions when surrounded by CSF. In nerves which were not surrounded by CSF, the 2D T1-weighted contrast-enhanced fat suppression technique was the best sequence.

CONCLUSIONS

A combination of 3D CISS, the 2D T1-weighted fat suppressed sequence and a 3D contrast-enhanced MP-RAGE proved to be the most useful sequence to visualize all lesions of the cranial nerves. For the determination of enhancement, an additional 3D MP-RAGE sequence without contrast medium is required. This sequence is also very sensitive for the detection of hemorrhage.

Value of high-resolution MR in patients scheduled for cochlear implantation

OBJECTIVE

To determine sensitivity and specificity of high-resolution MR imaging and of high-resolution axial CT (HRCT) and to compare the two modalities in predicting the surgical and functional success of cochlear implantation.

MATERIAL AND METHODS

The presurgical MR images (2D T2W TSE, 3D T2*W CISS, plain and contrast-enhanced 3D T1W MP-RAGE) and axial HRCT findings of 26 patients were evaluated with regard to the predictive value concerning the success of cochlear implantation.

RESULTS

We found a high correlation between MR and HRCT and the success of cochlear implantation. In all 26 patients, the MR-based predictions concerning the success of cochlear implantation were correct. In 10 patients, MR gave additional information to HRCT. In all patients, MR gave sufficient information about the status of the inner ear, inner auditory canal and cochlear nerve to aid the surgeon during the operation.

CONCLUSION

A high-resolution MR protocol consisting of coronal 2D T2W TSE, 3D T2*W axial CISS, plain and contrast-enhanced sagittal T1W 3D MP-RAGE is recommended for the evaluation of candidates scheduled for cochlear implantation. It provides information which cannot be obtained by HRCT.

[Indirect MR Arthrography of the wrist in the diagnosis of TFCC-Lesions]

PURPOSE

The objective of this prospective study was to assess the value of the indirect MR arthrography (MR-AR) of the wrist in the detection of lesions of the TFCC.

MATERIAL AND METHODS

Indirect MR-AR was performed in 45 patients (23 f/22 m) with unclear ulnar wrist pain. After i. v. injection of 0.1 mmol/kg Gd-DTPA and after a motion-phase of the wrist (15 minutes) MRI was performed in a coronal plane. We used a STIR-, a fatsaturated (fs) T1-SE and a 3D-DESS sequence. The images were evaluated by two radiologists using a consensus score. The lesions were assigned to the system of Palmer and correlated with arthroscopy.

RESULTS

Indirect MR-AR showed in 35 of 45 patients a lesion of the TFCC, but arthroscopy only revealed a defect in 32 cases. This means three false positive but no false negative assessments by MRI. Using this MRI protocol sensitivity and specificity in the detection of TFCC lesions were calculated as 100 % and 77 %. The accuracy was 93 %. Small degenerative changes of the fibres were most common (Palmer type II A). In trauma patients the ligaments usually showed tears near the insertion at the ulna (Palmer type I B). The sensitivity and specificity was 88 % and 95 % for evaluation of the scapho-lunate (SL) ligament, the accuracy was 93 %. Arthroscopy and MRI did not diagnose any rupture of the lunate-triquetral (LT) ligament.

CONCLUSION

Indirect MR-AR is a non-invasive method with a high sensitivity in the evaluation of the TFCC and associated injuries. Therefore, it is an excellent screening procedure to assess the indication for therapeutic arthroscopy.

Comparison of two-dimensional gradient echo, turbo spin echo and two-dimensional turbo gradient spin echo sequences in MRI of the cervical spinal cord anatomy

The aim of this study was to assess the detectability and distinguishability of the cervical spinal cord, the anterior and posterior spinal roots and of the internal anatomy of the cord (distinction of grey and white matter). For this purpose 20 healthy volunteers were examined using a 1.5 T MR unit with 20 mT/m gradient strength and a dedicated circular polarized neck array coil. Three T2* weighted (w). 2D gradient echo sequences, two T2 w. 2D turbo spin echo (TSE) sequences and one T2 w. 2D turbo gradient spin echo (TGSE) sequence were compared. The multiecho 2D fast low angle shot (FLASH) sequence with magnetization transfer saturation pulse (me FLASH+MTS) yielded the best results for liquor/compact bone, liquor/spinal cord and grey/white matter contrast, as found with regions of interest (ROI) analysis. The single echo 2D FLASH sequence was significantly poorer than the two me FLASH+/-MTS sequences. Two-dimensional TGSE as well as 2D TSE with a 256 matrix and with a 512 matrix yielded the poorest results. In the visual analysis the contrast between liquor and compact bone, liquor and cord as well as liquor and roots was best with me FLASH+MTS, whereas grey/white matter distinction was best using me FLASH-MTS. In conclusion, we would therefore recommend the inclusion of an axial T2* w. multiecho 2D spoiled gradient echo sequence with magnetization transfer saturation pulse and gradient motion rephasing in a MR imaging protocol of the cervical spine.

Visualization of the IXth to XIIth cranial nerves using 3-dimensional constructive interference in steady state, 3-dimensional magnetization-prepared rapid gradient echo and T2-weighted 2-dimensional turbo spin echo magnetic resonance imaging sequences

OBJECTIVE

The purpose of this study was to evaluate the visibility of the IXth to XIIth cranial nerves using different magnetic resonance sequences. Thirty healthy volunteers underwent magnetic resonance imaging at 1.5 T using 3-dimensional constructive interference in steady state (CISS) sequence (TR = 17 ms, TE = 8.08 ms, alpha = 70 degrees), 3-dimensional magnetization-prepared rapid gradient echo (MP-RAGE) sequence (TR = 11.08 ms, TE = 4.3 ms, alpha = 15 degrees), and T2-weighted (w) 2-dimensional turbo spin echo (TSE) sequence (TR = 4000 ms, TE = 102 ms, alpha = 180 degrees, slice thickness = 2 mm). Visibility of the IXth to XIIth cranial nerves in each sequence was evaluated by consensus of 2 radiologists using an evaluation scale from 1 (excellently visible) to 5 (not visible). A correlation with anatomic specimens was made. The 3-dimensional CISS sequence provides best resolution of the IXth to XIIth cranial nerves and their relation to surrounding structures. Additional information is given by the 3-dimensional MP-RAGE when nerves are surrounded by soft tissues. Using the T2w 2-dimensional TSE sequence, even whole nerves cannot be visualized due to intersection gap and partial volume effects. However, even in 3-dimensional high-resolution sequences, segments of nerves are not always visualized. A combination of 3-dimensional CISS and 3-dimensional MP-RAGE proved to be useful to visualize the IXth to XIIth cranial nerves, whereas the 2-dimensional technique failed. Further investigations using 3-dimensional MP-RAGE with contrast medium should be performed in the case of abnormality.

[Metastasis in the frontal skull base from hepatocellular carcinoma]

Metastatic tumours involving the nose and the paranasal sinuses are rare. Especially metastatic spread to the sphenoid sinus is an extremely rare occurrence. The most common metastatic tumour is the renal cell carcinoma. Only four cases of hepatocellular carcinoma presenting a sphenoid sinus metastasis could be found in a search of the literature. We report on the case of a 59-year-old male who suffered from a sphenoid sinus mass. A biopsy showed the tumour to be a metastatic hepatocellular carcinoma. The suspected primary tumour was then found in the left liver lobe. The early diagnosis of paranasal sinus malignancies is difficult because of the varied and nonspecific symptoms and signs. In cases of late diagnosis, the treatment is usually palliative with a poor prognosis. The importance of endoscopic examination and CT or MRI scan for early detection must be emphasized.

Comparison of 2-D turbo spin echo and 3-D gradient echo sequences for the detection of the trigeminal nerve and branches anatomy

The aim of this study was to assess the detectability of the trigeminal nerve and its branches using T1 weighted (w.) 3-D magnetization prepared rapid gradient echo (MP-RAGE), T2* w. 3D CISS and T2 w. 2-D turbo spin echo MR sequences. Thirty healthy volunteers were examined for this purpose using a 1.5 Tesla MR unit. The detectability of the trigeminal nerve and Gasser's Ganglion, i.e. structures that are surrounded by liquor was best using 3-D CISS. In the case of the ophthalmic, maxillary and mandibular nerves, the T1 w. 3-D MPRAGE was significantly better than T2* w. CISS and T2 w. 2-D turbo spin echo. The latter yielded the poorest results. We conclude that both high resolution T2* w. and T1 w. 3-D sequences are necessary in order to detect the liquor-surrounded trigeminal nerve and its soft tissue-surrounded branches. We would therefore recommend the inclusion of constructive interference in steady state (CISS) and MP-RAGE in a MR imaging protocol of the trigeminal nerve and its branches.