The German trial on Aciclovir and Corticosteroids in Herpes-simplex-virus-Encephalitis (GACHE): a multicenter, randomized, double-blind, placebo-controlled trial

Introduction

Comprehensive treatment of Herpes-simplex-virus-encephalitis (HSVE) remains a major clinical challenge. The current therapy gold standard is aciclovir, a drug that inhibits viral replication. Despite antiviral treatment, mortality remains around 20% and a majority of survivors suffer from severe disability. Experimental research and recent retrospective clinical observations suggest a favourable therapy response to adjuvant dexamethasone. Currently there is no randomized clinical trial evidence, however, to support the routine use of adjuvant corticosteroid treatment in HSVE.

Methods

The German trial of Aciclovir and Corticosteroids in Herpes-simplex-virus-Encephalitis (GACHE) studied the effect of adjuvant dexamethasone versus placebo on top of standard aciclovir treatment in adult patients aged 18 up to 85 years with proven HSVE in German academic centers of Neurology in a randomized and double blind fashion. The trial was open from November 2007 to December 2012. The initially planned sample size was 372 patients with the option to increase to up to 450 patients after the second interim analysis. The primary endpoint was a binary functional outcome after 6 months assessed using the modified Rankin scale (mRS 0-2 vs. 3-6). Secondary endpoints included mortality after 6 and 12 months, functional outcome after 6 months measured with the Glasgow outcome scale (GOS), functional outcome after 12 months measured with mRS and GOS, quality of life as measured with the EuroQol 5D instrument after 6 and 12 months, neuropsychological testing after 6 months, cranial magnetic resonance imaging findings after 6 months, seizures up to day of discharge or at the latest at day 30, and after 6 and 12 months.

Results

The trial was stopped prematurely for slow recruitment after 41 patients had been randomized, 21 of them treated with dexamethasone and 20 with placebo. No difference was observed in the primary endpoint. In the full analysis set (n = 19 in each group), 12 patients in each treatment arm achieved a mRS of 0-2. Similarly, we did not observe significant differences in the secondary endpoints (GOS, mRS, quality of life, neuropsychological testing).

Conclusion

GACHE being prematurely terminated demonstrated challenges encountered performing randomized, placebo-controlled trials in rare life threatening neurological diseases. Based upon our trial results the use of adjuvant steroids in addition to antiviral treatment remains experimental and is at the decision of the individual treating physician. Unfortunately, the small number of study participants does not allow firm conclusions.

Trial registration

EudraCT-Nr. 2005-003201-81.

Setting up a Neuroscience Stroke and Rehabilitation Centre in Brunei Darussalam by a transcontinental on-site and telemedical cooperation

Due to the world-wide aging population, there is a need for specialist neurological knowledge, treatment and care. Stroke treatment is effective in reducing mortality and disability, but it is still not available in many areas of the world. We describe the set-up process of a specialized Neuroscience, Stroke and Rehabilitation Centre in Brunei Darussalam (BNSRC) in cooperation with a German hospital. This study details the setup of a stroke-, neurological intensive care- and neurorehabilitation unit, laboratories and a telemedical network to perform all evidence-based stroke treatments. All neurological on-site services and the telemedical network were successfully established within a short time. After setup, 1386 inpatients and 1803 outpatients with stroke and stroke mimics were treated. All evidence-based stroke treatments including thrombolysis and hemicraniectomy could be performed. It is possible to establish evidence-based modern stroke treatment within a short time period by a transcontinental on-site and telemedical cooperation.

Intraoperative computed tomography and automated registration for image-guided cranial surgery

OBJECTIVES

Two key problems for the use of navigation systems in image-guided surgery are accurate patient-to-image registration and the fact that with ongoing surgery the patient's anatomy is altered while the image data remains unchanged. A system for intraoperative CT imaging and fully automated registration of this image addresses both problems. It had been evaluated successfully in phantom studies. In this clinical study, we assessed the impact of the system on intraoperative workflow and registration accuracy in everyday patient care.

METHODS

In ten patients who underwent image-guided surgery, CT image data were acquired intraoperatively and were automatically registered in the navigation system. Registration accuracy and surgical outcome were assessed clinically. In six of these patients, a maxillary splint with markers had been inserted to cross-check registration accuracy. The target registration error of these markers was measured.

RESULTS

In all cases, registration accuracy was clinically sufficient and the surgical task could be performed successfully. In those cases where a maxillary template with target markers was attached for additional control of the registration accuracy, the target registration error was always better than 2 mm. Automated registration reduced the intraoperative registration time considerably and partially compensated for the time needed to perform the image data acquisition.

CONCLUSIONS

Intraoperative CT imaging and automated registration successfully address the two key problems of image-guided surgery. The method is robust and accurate and proved its usability in everyday patient care.

Neuropathic pain resulting from implant placement: case report and diagnostic conclusions

Temporary or persisting dysesthesia of the nervus alveolaris inferior has often been described as a complication of implant surgery of the lower mandible. In most cases, lesion of the nerve results in anaesthesia of the innervated region, a symptom clearly indicative of correct diagnosis. In our case report, however, a minor perforation of the roof of the mandibular canal during implant placement apparently provoked discrete irritation of the nerve, resulting in persistent neuropathic pain without concomitant hypesthesia or dysesthesia. Because the canal could not be detected in conventional dental radiographs, this uncharacteristic situation made correct diagnosis difficult and led to unnecessary surgical procedures including extraction of adjacent teeth. Medical imaging [computed tomography (CT)] finally revealed the close proximity of the apex of the implant and the bony structure of the mandibular canal. The effect on the nervus alveolaris inferior was also demonstrated using an innovative high-resolution dental magnetic-resonance-imaging technique reflecting vascular reactions of the neurovascular bundle after potentially damaging surgical intervention. After removal of the causative implant, the pain gradually faded over a period of a year.

Loss of anisotropy in trigeminal neuralgia revealed by diffusion tensor imaging

We studied the trigeminal nerve in seven healthy volunteers and six patients with trigeminal neuralgia using the diffusion tensor imaging derived parameter fractional anisotropy (FA). While controls did not show a difference between both sides, there was a reduction of FA in the affected nerve in three of six patients with accompanying nerve-vessel conflict and atrophy. Reversibility of abnormally low FA values was demonstrated in one patient successfully treated with microvascular decompression.

[Injury of craniocervical arteries: imaging findings and therapy]

Direct or indirect injury of craniocervical vessels may be the consequence of an accident, may result from tumor arrosion, or may even occur spontaneously. Many of these vascular lesions can be detected using modern non-invasive vascular imaging techniques such as CT angiography and MR angiography. These traumatic vascular lesions can usually be treated using endovascular techniques. This overview describes neuroradiological findings for traumatic lesions of cervical and cranial vessels as well as endovascular treatment options.

Subarachnoid hemorrhage due to Borrelia burgdorferi-associated vasculitis

We report the case history of a patient who suffered a subarachnoid hemorrhage (SAH) in association with early Lyme neuroborreliosis. After a tick bite, this patient developed erythema chronicum migrans and complained of stinging radicular pain in both legs. A computed tomography (CT) scan was performed because of acute headache and nuchal rigidity, which revealed an occipital SAH. Cerebrospinal fluid analysis provided further evidence of acute neuroborreliosis. Digital substraction angiography showed irregularities in the right posterior cerebral artery, which might be due to vasculitis, but no aneurysms.

Repeated digital substraction angiography after perimesencephalic subarachnoid hemorrhage?

BACKGROUND AND PURPOSE

In patients with perimesencephalic subarachnoid hemorrhage (pSAH) DSA is recommended to exclude aneurysms to due false negative findings in CT-angiography. However, whether a second DSA is indicated during the clinical course to exclude--in addition to aneurysms--fistulas, too, is still under debate. We aimed to evaluate the benefit of repeated DSA in patients with pSAH.

METHODS

The source of data was a prospective database set up at the neurological, neurosurgical and neuroradiological departments in our institution. A total of 69 patients with pSAH were enrolled and analyzed by reviewing the medical records and neuroradiological findings.

RESULTS

68 patients presented with Hunt & Hess Grade I-II and one patient with Hunt & Hess Grade III. Median in-hospital stay was 8 days (3-22). In 2 patients mild vasospasm were diagnosed. DSA was performed in all patients at least once. DSA was repeated in 38 patients (55%) after a median of 7 (3-21) days. None of the repeated DSA did show any additional distinctive features with respect to the first DSA.

CONCLUSIONS

In our opinion the procedure of repeating DSA in patients with pSAH is likely to become obsolete. One DSA should be performed prior to discharge--and subsequent to possible vasospasm--to exclude hemorrhage caused by aneurysms of the posterior circulation mimicking a perimesencephalic SAH pattern.

Trigeminusneuralgie: Wie häufig gibt es einen Gefäß-Nerven-Kontakt bei schmerzfreien Probanden?

PURPOSE

To assess prospectively how often contacts are found between the trigeminal nerve and arteries or veins in the perimesencephalic cistern via MRI in normal volunteers.

MATERIALS AND METHODS

48 volunteers without a history of trigeminal neuralgia were examined prospectively (MRI at 1.5 T; T2-CISS sequence, coronal orientation, 0.9 mm slice thickness). Two radiologists decided by consensus whether there was a nerve-vessel contact in the perimesencephalic cistern.

RESULTS

In 27 % of the volunteers, no contact was found between the trigeminal nerve and regional vessels, while in 73 %, such a contact was present. In 61 % of the cases, the offending vessel was an artery, in 39 %, it was a vein. In 2 volunteers, a deformation of the nerve was noted.

CONCLUSION

Contrary to what has been suggested by retrospective studies, the majority of normal volunteers, if studied prospectively, do show a contact between the trigeminal nerve and local vessels. A close proximity between the nerve and regional vessels is thus normal and is not necessarily proof of a pathological nerve-vessel conflict.

Epidurale Rückenmarkstimulation bei Postnukleotomiesyndrom

BACKGROUND

Spinal cord stimulation (SCS) is an effective alternative treatment in patients with chronic neuropathic pain and mainly radicular distribution. The aim of this prospective study was to investigate changes in BOLD signal with fMRI during active SCS and to correlate the results with the clinical pain intensity, measured with a visual analogue scale (VAS).

PATIENTS AND METHODS

Three patients with failed back surgery syndrome were tested during the clinical trial of SCS. A first fMRI was performed with marked pain and a high VAS score. Before the second fMRI a therapeutic stimulation phase with pain reduction was carried out.

RESULTS

With high pain levels SCS activated the cingulate gyrus, thalamus, prefrontal cortex, supplementary motor area and postcentral gyrus. After pain reduction, SCS did not elicit these activations in the second fMRI, using the same stimulation parameters.

CONCLUSIONS

In patients with chronic neuropathic pain and high VAS levels, SCS elicited BOLD activation in the cingulate gyrus, thalamus, prefrontal cortex, and primary and secondary somatosensory area. Pain reduction by SCS resulted in a reduction of functional activity in these areas as revealed by follow-up fMRI.

[Infectious diseases of brain parenchyma in adults: imaging and differential diagnosis aspects]

Infectious diseases of the central nervous system have often to be considered in differential diagnosis, particularly in immunocompromised persons. Neuroimaging, specifically advanced techniques such as diffusion-weighted MRI and perfusion MRI contribute much to the differentiation of various brain infections and to delineation of brain infections from other, for instance, neoplastic diseases. In this review we present the imaging criteria for the most important brain infections in adults and discuss in detail differential diagnostic aspects.

Treatment of trigeminal neuralgia associated with multiple sclerosis: case report

The incidence of trigeminal neuralgia (TN) in patients with multiple sclerosis is higher than in the general population. If pharmacologic therapy fails, invasive procedures in the gasserian ganglion are usually offered. Microvascular decompression is not routinely performed. The authors report a patient with persistent TN after repetitive trigeminal radiofrequency rhizotomy and finally successful microvascular decompression after demonstration of neurovascular compression with high-resolution MRI.

Geometric accuracy of magnetic resonance imaging of the mandibular nerve

OBJECTIVES

Magnetic resonance imaging (MRI) is not routinely used for dental implant planning. A prerequisite for dental implant planning is the accurate imaging of risk structures like the mandibular nerve. The geometric accuracy of the imaging of the mandibular nerve was investigated.

METHODS

Two human cadaver heads were scanned using MRI. Computed tomography (CT) scans of the same heads were used as a benchmark. Using a stereotactic frame, corresponding images of MRI and CT were superimposed and the concordance of the images of the mandibular nerve in MRI with those of the mandibular canal in CT was assessed.

RESULTS

The geometric accuracy of the mandibular nerve in MRI was as good as that of the mandibular canal in CT imaging.

CONCLUSIONS

MRI of the mandibular nerve is sufficiently accurate for the use of this imaging method in dental implant planning.

[Temporomandibular joint: MRI diagnostics]

MRI of the temporomandibular joint (TMJ) requires 1.5 T. The radiologist must be familiar with the anatomy and pathology of the TMJ. This review gives a description of MRI protocols for the TMJ, and MRI anatomy and pathology of the TMJ (open and closed mouth) by means of MR images and drawings. Diagnosing of the TMJ related diseases depends on standardized clinical and MR examinations. Therefore close interdisciplinary cooperation between dentist and radiologist is necessary.

Hemorrhagic acoustic schwannoma: radiological and histopathological findings

A 49-year-old man on anticoagulation treatment with phenprocoumon presented with acute right sided 7th and 8th cranial nerve palsy, acute hearing loss, headache, vertigo, and vomiting. CT and MRI revealed a cerebellopontine angle tumor 15mm in diameter and acute intratumoral hematoma. A cellular schwannoma composed predominantly of Antoni A tissue with dilated thin-walled vessels, surrounded by old hemorrhage with hemosiderin-laden macrophages was found histologically.

Beeinflusst die individuelle Anpassung standardisierter Sprachparadigmen für die klinische funktionelle Magnetresonanztomographie (fMRT) die Lokalisation der sprachdominanten Hemisphäre, des Broca- und des Wernicke-Sprachzentrums?

PURPOSE

Functional magnetic resonance imaging (fMRI) localizes Broca's area (B) and Wernicke's area (W) and the hemisphere dominant for language. In clinical fMRI, adapting the stimulation paradigms to each patient's individual cognitive capacity is crucial for diagnostic success. To interpret clinical fMRI findings correctly, we studied the effect of varying frequency and number of stimuli on functional localization, determination of language dominance and BOLD signals.

MATERIALS AND METHODS

Ten volunteers (VP) were investigated at 1.5 Tesla during visually triggered sentence generation using a standardized block design. In four different measurements, the stimuli were presented to each VP with frequencies of 1/1 s, (1/2) s, (1/3) s and (1/6) s.

RESULTS

The functional localizations and the correlations of the measured BOLD signals to the applied hemodynamic reference function (r) were almost independent from frequency and number of the stimuli in both hemispheres, whereas the relative BOLD signal changes (DeltaS) in B and W increased with the stimulation rate, which also changed the lateralization indices. The strongest BOLD activations were achieved with the highest stimulation rate or with the maximum language production task, respectively.

CONCLUSION

The adaptation of language paradigms necessary in clinical fMRI does not alter the functional localizations but changes the BOLD signals and language lateralization which should not be attributed to the underlying brain pathology.

The effect of quality of temporomandibular joint MR images on interrater agreement

OBJECTIVES

Effects of calibration on interrater agreement in evaluating magnetic resonance (MR) images of the temporomandibular joint (TMJ) have already been examined. The objectives of the present study were to assess to what extent the quality of MR images of the TMJ influences interrater agreement and to evaluate interrater agreement with respect to image quality assessment.

METHODS

Two non-calibrated medical radiologists and two general dentists evaluated sagittal images of 100 TMJs for both a rating of the image quality and the performance of five diagnostic tasks. The agreement between these raters with respect to the diagnoses was evaluated. Additionally, two additional raters, calibrated during a 5 h training including the evaluation of 70 MR images, also evaluated the diagnostic aspects and the image quality, on the basis of objective criteria. The agreement between the subjective diagnoses of the non-calibrated raters and the objective diagnoses of the calibrated raters was evaluated. Afterwards, the subjective and the objective quality assessments were compared using kappa statistics.

RESULTS

When good quality images were evaluated, higher kappa values were obtained for all diagnostic categories by the non-calibrated raters (mean Deltak for making diagnoses >0.1). This finding was confirmed by the value obtained for the agreement between the non-calibrated and the calibrated raters. The non-calibrated raters were in good agreement (k=0.67, standard error +/-0.09) with the calibrated raters for assessment of image quality.

CONCLUSION

The present study shows that it is possible even without calibration to obtain a better interrater agreement when higher quality MR images of the TMJ are evaluated.

Quantitative analysis of MRI signal intensity as a tool for evaluating tooth pulp vitality

OBJECTIVES

To assess whether it is possible to measure tooth vitality using magnetic resonance imaging (MRI).

METHODS

Signal intensity measurements were conducted using T(1) and T(2) sequences at the region of interest in 211 teeth (35 patients).

RESULTS

Clinical findings showed that 17.3% of the teeth were avital, whereas 82.7% were found to be vital. Neither the T(2) sequence nor the non-contrast-enhanced T(1) sequence showed significant differences between vital and avital teeth. However, the contrast-enhanced sequence and, in particular, a comparison of signal intensities between the non-contrast-enhanced T(1) sequence and the contrast-enhanced sequence showed a significant difference between vital and avital teeth.

CONCLUSION

Contrast-enhanced MRI enables us to draw conclusions on pulpal perfusion in vivo.

[Benign diseases of the mandible in MRI]

Diseases of the mandible affect the soft tissues aside from the osseous manifestation. This can be shown clearly and in great detail by magnetic resonance imaging (MRI). MRI is the gold standard in the diagnostic evaluation of any internal derangement of the temporomandibular joint. Dental MRI requires high resolution techniques and in some cases also intravenous administration of contrast material. These techniques allow delineation of the neurovascular bundle. In the past few years new indications were formulated, for example, the evaluation of the integrity of the inferior alveolar nerve in trauma and in radicular cysts. New quantitative methods now enable insights into the pathophysiology. The objective of this review is to communicate accepted indications for MRI of the mandible and to present innovative applications.

MR-Volumetrie des N. trigeminus bei Patienten mit einseitigen Gesichtsschmerzen

PURPOSE

To assess whether MRI can detect atrophy of the trigeminal nerve in patients with trigeminal neuralgia.

MATERIALS AND METHODS

A prospective MRI study was conducted in 39 patients (trigeminal neuralgia, trigeminal neuropathy, or atypical facial pain) and 25 volunteers. Using a coronal orientation (T1 Flash 3D; T2 CISS 3D), regions of interest were delineated in the cisternal part of the trigeminal nerve along the border of the nerve to calculate the volume of the nerve. The volume of the nerve was compared side-by-side in each patient (t-test, p < 0.05) and the volume difference compared between patients and volunteers.

RESULTS

The volume of the compromised trigeminal nerve in patients with trigeminal neuralgia was lower than on the contralateral healthy side, with the difference between healthy and compromised side statistically significant (p < 0.05). In all other patients and in all volunteers, no significant difference was found between the volume of the healthy and compromised nerve. The volume difference between the healthy and compromised side in patients with trigeminal neuralgia was significantly higher (p < 0.05) than in all other patients and volunteers.

CONCLUSION

Atrophy of the trigeminal nerve caused by a nerve-vessel conflict can be detected by MRI. Only patients with trigeminal neuralgia show this unilateral atrophy. Therefore, it is possible to demonstrate the result of the nerve-vessel conflict and to determine the consequences of such a conflict.

High-resolution dental magnetic resonance imaging of inferior alveolar nerve responses to the extraction of third molars

The objective of this study was to assess whether signal changes can be detected in the neurovascular bundle of the mandibular canal after the extraction of a third molar. We retrospectively analyzed MRI scans of 30 test subjects with healthy mandibles and 41 patients who had had a wisdom tooth extracted. Signal intensities were measured at particular sites in the neurovascular bundle, which were defined as regions of interest (ROI) in the sagittal T1-weighted images before and after intravenous administration of a paramagnetic contrast agent. On the basis of the signal intensity increases that were measured after contrast agent administration, we compared the signal increases obtained for the patients who had received surgical treatment with the results obtained for the population of test subjects with unremarkable mandibles ( t-test, P<0.05). Compared with the healthy test subjects, patients who had received surgical treatment showed significantly higher signal intensity increases at two measurement sites, i.e., the second molar and the second premolar ( P<0.05). We found no significant differences when the measurements were performed at the first molar ( P=0.06), the third molar ( P=0.47) and in the area of the ascending mandibular ramus ( P=0.79). Compared with a population of healthy test subjects, patients who had their third molars surgically removed show higher signal intensity increases in the neurovascular bundle after intravenous contrast agent administration. The underlying cause may be the higher blood flow in the arteries and veins and the perineural plexus, which may give evidence of the pathophysiological mechanism of nerve damage in the narrow canal as a result of osteotomy.

Quantitative Analyse der MR-Signal-Intensit�t des N.�petrosus major bei Patienten mit idiopathischer Fazialisparese

The objective of this study was to evaluate signal intensity increases in the greater petrosal nerve after contrast agent administration to gather information on the etiology of idiopathic peripheral facial paralysis. Magnetic resonance images were obtained from 18 patients who received inpatient medical treatment for acute peripheral facial nerve palsy. Images of intratemporal segments of the facial nerve were taken with a slice thickness of 0.75 mm. After multiplanar reconstruction, regions of interest (ROI) were defined in the proximal segment of the greater petrosal nerve. After multiplanar reconstruction, it was possible to visualize the greater petrosal nerves of all 18 patients. The nerve's average diameter was found to be 0.68 mm (range 0.5-0.9). Signal intensity increased by an average of 50.3% (range -10-146%) after contrast agent administration. Whereas this intensity was slightly reduced in two patients, it was increased in 16. No correlation could be established between greater signal intensity and medical history, clinical condition, laboratory findings, or electrophysiological data. In contrast to quantitative measurements in the facial nerve, ROI measurements in the greater petrosal nerve do not correlate with medical history, clinical condition, or laboratory findings. For this reason, MRI of this nerve does not enable us to draw conclusions on the etiology of idiopathic peripheral facial paralysis.

Edema and brain trauma

Brain edema leading to an expansion of brain volume has a crucial impact on morbidity and mortality following traumatic brain injury (TBI) as it increases intracranial pressure, impairs cerebral perfusion and oxygenation, and contributes to additional ischemic injuries. Classically, two major types of traumatic brain edema exist: "vasogenic" due to blood-brain barrier (BBB) disruption resulting in extracellular water accumulation and "cytotoxic/cellular" due to sustained intracellular water collection. A third type, "osmotic" brain edema is caused by osmotic imbalances between blood and tissue. Rarely after TBI do we encounter a "hydrocephalic edema/interstitial" brain edema related to an obstruction of cerebrospinal fluid outflow. Following TBI, various mediators are released which enhance vasogenic and/or cytotoxic brain edema. These include glutamate, lactate, H(+), K(+), Ca(2+), nitric oxide, arachidonic acid and its metabolites, free oxygen radicals, histamine, and kinins. Thus, avoiding cerebral anaerobic metabolism and acidosis is beneficial to control lactate and H(+), but no compound inhibiting mediators/mediator channels showed beneficial results in conducted clinical trials, despite successful experimental studies. Hence, anti-edematous therapy in TBI patients is still symptomatic and rather non-specific (e.g. mannitol infusion, controlled hyperventilation). For many years, vasogenic brain edema was accepted as the prevalent edema type following TBI. The development of mechanical TBI models ("weight drop," "fluid percussion injury," and "controlled cortical impact injury") and the use of magnetic resonance imaging, however, revealed that "cytotoxic" edema is of decisive pathophysiological importance following TBI as it develops early and persists while BBB integrity is gradually restored. These findings suggest that cytotoxic and vasogenic brain edema are two entities which can be targeted simultaneously or according to their temporal prevalence.

[Quantitative analysis of contrast enhanced MRI of the inferior alveolar nerve in inflammatory changes of the mandible]

PURPOSE

To evaluate the role of contrast enhanced MRI in quantifying signal changes of the inferior alveolar nerve following inflammatory changes of the mandible.

MATERIAL AND METHODS

30 patients with inflammatory changes of the mandible underwent MRI of the face. Both sides of the mandible, the affected as well as the unaffected healthy side were evaluated retrospectively. Regions of interest were placed at 5 defined places on both sides to assess signal intensity before and after intravenous application of paramagnetic contrast agent. The results of the measurements were compared between the healthy and the affected side (t-test, p < 0.05) and correlated with clinical findings (t-test, p < 0.05).

RESULTS

All patients with hypesthesia of the inferior alveolar nerve in areas of the lips or chin (n = 4) showed a marked increase in signal intensity from 35 % to 83 % distal to the inflammatory process. Patients without sensitivity disorders showed less increase in signal intensity with a maximum of 51 % distal to the inflammatory process. In nearly all patients no contrast enhancement was observed distal to the first molar on the unaffected side.

CONCLUSIONS

Quantitative analysis of contrast enhanced MRI of the neurovascular bundle is able to show pathologic mandibular lesions. In case of inflammatory changes of the mandible the neurovascular bundle is able to show pathologic mandibular lesions. In case of inflammatory changes of the mandible, the neurovascular bundle shows a significant increase in signal intensity distal to the lesion compared to the unaffected healthy side of the mandible.

MR imaging of traumatic lesions of the inferior alveolar nerve in patients with fractures of the mandible

BACKGROUND AND PURPOSE

The objective of this study was to assess whether MR imaging can image the neurovascular bundle in patients with fractures of the mandible. In addition, an attempt was made to evaluate whether MR images provide information regarding the continuity of the inferior alveolar nerve before surgery and regarding signal intensity changes after trauma.

METHODS

We analyzed preoperative MR images of 23 patients with mandibular fractures. Object-oriented sagittal view proton density- and T1-weighted sequences (before and after the administration of contrast agent) were used not only in an attempt to obtain purely qualitative information regarding nerve continuity in the neurovascular bundle (inferior alveolar nerve, artery, vein) but also to perform quantitative region-of-interest measurements of signal intensities at four defined measurement sites. The measurements were compared with those obtained for a patient population with healthy mandibles.

RESULTS

It was possible to interpret MR images in 21 cases. MR imaging findings showed that the neurovascular bundle had been cut in two patients and was intact in the remaining 19 patients. These MR imaging findings were confirmed intraoperatively in all cases. Although we found no significant signal intensity differences between patients with intact nerves and patients with cut nerves, we found significant differences between patients with mandibular fractures and patients with unremarkable mandibles.

CONCLUSION

It is possible to diagnose the interruption of nerve continuity by using MR imaging. Signal intensity measurements in the neurovascular bundle provide no information regarding nerve continuity.