MRI volumetry for the preoperative diagnosis of trigeminal neuralgia

To assess whether quantitative measuring methods can help improve the reliability of MRI-based evaluations of the pathological role of a neurovascular conflict between an artery and the trigeminal nerve. In a prospective study, magnetic resonance images were obtained from 62 patients with unilateral facial pain and 50 healthy test subjects. In coronal T1- and T2-weighted sequences volume measurements were performed by regions of interest and compared intraindividually (healthy versus affected side in the patient populations and right versus left side in the group of test subjects) and on the basis of the different clinical pictures (t test for dependent and independent samples, p<0.05). In patients with trigeminal neuralgia, the affected nerve showed a smaller volume than the trigeminal nerve on the healthy side (p<0.001). Such a volume difference was noted neither in the other patients nor in the healthy test subjects. Quantitative MRI measurements allow a pathological neurovascular conflict to be distinguished from a nonpathological condition where an artery is in close proximity to the trigeminal nerve. The measured volume difference between the healthy and the affected nerve in patients with neuralgia is indicative of trigeminal nerve atrophy resulting from damage to the nerve.     

Bell palsy: quantitative analysis of MR imaging data as a method of predicting outcome

PURPOSE: To assess the prognostic value of quantitative analyses of region-of-interest (ROI) magnetic resonance (MR) imaging data in patients with acute facial nerve palsy. MATERIALS AND METHODS: In a single-blinded study, MR images were obtained in 39 patients (32 men and seven women; age range, 18-75 years; average age, 37.9 years) with acute facial nerve palsy. MR images were obtained before the 6th day of illness, on the first day of standard inpatient treatment with high-dose steroids. Signal intensity (SI) was measured at ROIs in each of five segments (internal auditory canal [IAC]; geniculate ganglion; and labyrinth, tympanic, and mastoid segments) of the intratemporal portion of the facial nerve and quantitatively analyzed. The SI measurements in the five segments were summed and divided by 100 to provide a basis for establishing an MR imaging index. SI increases and MR imaging indexes were compared with available clinical findings and electrophysiologic data. RESULTS: Data for all 39 patients could be analyzed. The MR imaging index was significantly higher in patients with poor outcomes than in patients with favorable outcomes (specificity, 97%; sensitivity, 75%; P <.01). The SI increases in the IAC were significantly different between patients who progressed to full recovery (mean increase, 45.7%) and patients who developed chronic facial paralysis (mean increase, 156.5%) (sensitivity, 100%; specificity, 97%; P <.001). The results of differentiating between patients with good and those with poor outcomes on the basis of SI measurements in the IAC were found to be in complete agreement with electrophysiologic data. CONCLUSION: Quantitative analysis of ROI MR imaging data is a valid method of predicting the outcome of acute facial nerve palsy during the first days after onset of symptoms and thus at a time when it is not yet possible to obtain valuable prognostic information by using electrophysiologic methods.     

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.     

Magnetic source imaging of tactile input shows task-independent attention effects in SII

We investigated whether attention to different stimulus attributes (location, intensity) has different effects on the activity of the secondary (SII) somatosensory cortex. Tactile stimuli were applied to the left index finger and somatosensory evoked fields (SEFs) were recorded using a whole-head magnetoencephalography (MEG) system. Two oddball paradigms with stimuli varying in location or intensity were performed in an ignore and an attend condition. Brain sources were estimated by magnetic source imaging. No attention effect was observed for the primary SI area. However, attention enhanced SII activity bilaterally from 55 to 130 ms by 52% in the spatial and 64% in the intensity discrimination task. SII attentional enhancement was very similar in both paradigms and occurred both for deviants and standards.     

Fast temporal interactions in human auditory cortex

The temporal resolution of the human primary auditory cortex (AC) was studied using middle-latency evoked fields. Paired sounds with either the same or different spectral characteristics were presented with gaps between the sounds of 1, 4, 8 and 14 ms. Spatio-temporal modelling showed (1) that the response to the second sound was recognizable with gaps of 1 ms and rapidly increased in amplitude with increasing gap durations, (2) an enhanced N40m amplitude at gaps > 4 ms, (3) delayed N19m-P30m latencies when the stimuli were different. The median psychoacoustical thresholds were 1.6 ms for the same stimuli and 2.5 ms for different stimuli, confirming the electrophysiological evidence for rapid pattern-specific temporal processing in human primary auditory cortex.     

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.     

Subakut sklerosierende Panenzephalitis nach Masernexposition im Säuglingsalter

Background

Subacute sclerosing panencephalitis (SSPE) is a lethal complication of measles virus infection. A risk factor for developing SSPE is measles exposure preceding the first vaccination. We report on two cases of SSPE with different clinical courses.

Case presentation

Both patients acquired an inapparent measles infection during their first year of life. They were vaccinated according to the current national recommendations. On reaching school age, early symptoms of SSPE were apparent and severe encephalopathy developed. Necrotizing chorioretinitis was observed in one of the patients. Only one patient was able to receive immunomodulatory treatment which induced transient clinical improvement.

Conclusion

SSPE should always be considered as a differential diagnosis in progressive encephalopathy in childhood. The disease can only be prevented by consistent measles vaccination in all children to minimize the risk of infection.