Spyros Karampekios

Patients with horizontal gaze palsy and progressive scoliosis due to ROBO3 E319K mutation have both uncrossed and crossed central nervous system pathways and perform normally on neuropsychological testing

Background: Horizontal gaze palsy and progressive scoliosis (HGPPS) is caused by mutations of the ROBO3 gene, which encodes a receptor associated with axonal guidance during development. Although there is evidence for uncrossed cuneatal and corticospinal tracts in HGPPS, it is unclear whether other central nervous system pathways are involved. Objective: To study two patients with HGPPS homozygotic for the ROBO3 E319K mutation using a variety of neurophysiological and neuropsychological tests. Methods: A battery of neuropsychological tests was applied to assess various cognitive and perceptual functions. The corticospinal, somatosensory and auditory pathways were evaluated using appropriate neurophysiological tests. To access motor pathways to the neck muscles, electromyographic recordings were obtained from the sternocleidomastoideus and splenius capitis muscle during active head rotation. Results: Both patients performed normally on manual dexterity, complex sensory and visuospatial functions, reading and general intelligence tests. Motor evoked potentials in both patients showed uncrossed corticospinal tracts for the extremities, although in one patient, electromyography indicated pyramidal tract crossing for the neck muscles. Although somatosensory evoked potentials showed uncrossed somatosensory fibres subserving proprioception and light touch, right median nerve somatosensory evoked potential in one patient indicated a partial lemniscal crossing. Sympathetic skin response and blink reflex showed a midline crossing of the spinothalamic and quintothalamic tracts. Brain stem auditory evoked potentials indicated a lack of crossing in the level of the trapezoid body. Conclusions: Our patients with the ROBO3 E319Κ mutation show normal perceptual and cognitive functions and have both crossed and uncrossed motor, sensory and auditory pathways.

T2 relaxation time analysis in patients with multiple sclerosis: correlation with magnetization transfer ratio

The aim of the current study was to perform T2 relaxation time measurements in multiple sclerosis (MS) patients and correlate them with magnetization transfer ratio (MTR) measurements, in order to investigate in more detail the various histopathological changes that occur in lesions and normal-appearing white matter (NAWM). A total number of 291 measurements of MTR and T2 relaxation times were performed in 13 MS patients and 10 age-matched healthy volunteers. Measurements concerned MS plaques (105), NAWM (80), and “dirty” white matter (DWM; 30), evenly divided between the MS patients, and normal white matter (NWM; 76) in the healthy volunteers. Biexponential T2 relaxation-time analysis was performed, and also possible linearity between MTR and mean T2 relaxation times was evaluated using linear regression analysis in all subgroups. Biexponential relaxation was more pronounced in “black-hole” lesions (16.6%) and homogeneous enhancing plaques (10%), whereas DWM, NAWM, and mildly hypointense lesions presented biexponential behavior with a lower frequency(6.6, 5, and 3.1%, respectively). Non-enhancing isointense lesions and normal white matter did not reveal any biexponentional behavior. Linear regression analysis between monoexponential T2 relaxation time and MTR measurements demonstrated excellent correlation for DWM(r=−0.78, p<0.0001), very good correlation for black-hole lesions(r=-0.71, p=0.002), good correlation for isointense lesions(r=−0.60, p=0.005), moderate correlation for mildly hypointense lesions(r=−0.34, p=0.007), and non-significant correlation for homogeneous enhancing plaques, NAWM, and NWM. Biexponential T2 relaxation-time behavior is seen in only very few lesions (mainly on plaques with high degree of demyelination and axonal loss). A strong correlation between MTR and monoexponential T2 values was found in regions where either inflammation or demyelination predominates; however, when both pathological conditions coexist, this linear relationship is lost.

Fractional anisotropy and mean diffusivity measurements on normal human brain: comparison between low-and high-resolution diffusion tensor imaging sequences.

Non-invasive in vivo visualization of white matter fiber tracts is currently feasible by means of diffusion tensor imaging (DTI) techniques. DTI-derived metrics, like fractional anisotropy (FA) and mean diffusivity (MD), have the potential to improve tissue characterization. Technical optimization of diffusion tensor sequences, including signal-to-noise ratio and spatial resolution, was performed for 20 normal subjects. High- and low-resolution DTI sequences were applied on all subjects and FA, MD parametric maps were reconstructed for both protocols. Voxel-based statistical analysis revealed regions with significantly different FA and MD values between the two sequences, while the same type of analysis was performed to illustrate regions with significantly different signal-to-noise ratio. In conclusion, optimized DTI sequences may be applied routinely in clinical practice with a standard MR scanner, while accurate quantification of FA and MD may improve lesion characterization.

The silent epidural abscess as a complication of acute otitis media in children

Acute otitis media with complications is a persistent problem in the modern antibiotic era with a relatively high mortality rate. Acute mastoiditis is a serious complication of acute otitis media with potentially grave consequences and the epidural abscess constitutes the commonest of all intracranial complications, arising from middle ear infections. We report two cases of children with acute mastoiditis without evidence of intracranial complication or subperiosteal abscess, in whom the early evaluation with computed tomography (CT) disclosed an unsuspected epidural abscess. Therefore, we stress the use of CT as a rule of thumb for every child with acute mastoiditis.

Dosimetric characteristics of a 16-slice computed tomography scanner

Standard CT dose measurements were performed on a Siemens Sensation 16 scanner. CT dose indices, free-in-air (CTDIF) and weighted (CTDIW), were measured in all available axial and helical beam collimations of the head and body scanning modes. The effect of tube current, high voltage, rotation time, beam collimation and pitch on the CT doses was investigated. CT doses increased as a power function of high voltage. The kVp exponent n varied with beam collimation from 2.7 to 3.1 for CTDIW, and from 2.4 to 2.6 for CTDIF. Automatic change of the focal spot size increased radiation doses up to a factor of 1.18. Measured small-focus CTDIW values differed from those displayed at the console from –24 to 14%. Peripheral doses in the head phantom were higher compared to the body phantom by a factor of 1.5 to 2. Central doses are 2.7 to 4.1 times higher. Differences in beam collimation resulted in 50% variation in the CTDIW in the body phantom and 60% in the head phantom. In conclusion, our study has confirmed the great impact of technique factors and acquisition parameters on CT doses. The provided comprehensive dosimetric data will facilitate the dose-effective use of the scanner studied.

Quantification of magnetization transfer rate and native T1 relaxation time of the brain: correlation with magnetization transfer ratio measurements in patients with multiple sclerosis

The purpose of this paper is to perform quantitative measurements of the magnetization transfer rate (Kfor) and native T1 relaxation time (T1free) in the brain tissue of normal individuals and patients with multiple sclerosis (MS) by means of multiple gradient echo acquisitions, and to correlate these measurements with the magnetization transfer ratio (MTR). Quantitative magnetization transfer imaging was performed in five normal volunteers and 12 patients with relapsing–remitting MS on a 1.5 T magnetic resonance (MR) scanner. The T1 relaxation time under magnetization transfer irradiation (T1sat) was calculated by means of fitting the signal intensity over the flip angle in several 3D spoiled gradient echo acquisitions (3°, 15°, 30°, and 60°), while a single acquisition without MT irradiation (flip angle of 3°) was utilized to calculate the MTR. The Kfor and T1free constants were quantified on a pixel-by-pixel basis and parametric maps were reconstructed. We performed 226 measurements of Kfor, T1free, and the MTR on normal white matter (NWM) of healthy volunteers (n=50), and normal-appearing white matter (NAWM) and pathological brain areas of MS patients (n=120 and 56, respectively). Correlation coefficients between Kfor–MTR, T1free–MTR, and T1free–Kfor were calculated. Lesions were classified, according to their characteristics on T1-weighted images, into isointense (compared to white matter), mildly hypointense (showing signal intensity lower than white matter and higher than gray matter), and severely hypointense (revealing signal intensity lower than gray matter). “Dirty” white matter (DWM) corresponded to areas with diffused high signal, as identified on T2-weighted images. Strong correlation coefficients were obtained between MTR and Kfor for all lesions studied (r2=0.9, p<0.0001), for mildly hypointense plaques (r2=0.82, p<0.0001), and for DWM (r2=0.78, p=0.0007). In contrast, comparison between MTR and T1free values yielded rather low correlation coefficients for all groups assessed. In severely hypointense lesions, an excellent correlation was found between Kfor and T1free measurements (r2=0.98, p<0.0001). Strong correlations between Kfor and T1free were found for the rest of the subgroups, except for the NAWM, in which a moderate correlation was obtained (r2=0.5, p<0.0001). We conclude that Kfor and T1free measurements are feasible and may improve our understanding of the pathological brain changes that occur in MS patients.

Artificial paravertebral widening for percutaneous CT-guided adrenal biopsy.

A percutaneous adrenal biopsy under CT guidance is described. The biopsy was performed after injection of physiologic saline solution into the paravertebral space, creating a wider pathway for needle insertion. This technique has been previously reported for biopsy of thoracic lesions, but in our case it was used for biopsy of a relatively inaccessible adrenal lesion. This artificial window that is formed by displacing the pleura laterally allows a direct and potentially safer access route to the retroperitoneum, avoiding puncture of pleura, diaphragm, and abdominal structures.

Transverse Myelitis Associated With Herpes Simplex Virus Infection

The case of an otherwise healthy 6-year-old boy with symptoms and signs of acute transverse myelitis is presented. The diagnosis was confirmed by magnetic resonance imaging. An episode of gingivostomatitis had preceded, and serology indicated herpes simplex virus type 1 infection. The child recovered gradually, and no relapses were noted during a 30-month follow-up period. (J Child Neurol 2001;16:866—867).

Osteoblastoma of the nasal cavity arising from the perpendicular plate of the ethmoid bone

The presence of a benign osteoblastoma in the ethmoid sinus is rare and only a few cases have been reported. This is a case of a benign osteoblastoma arising from the perpendicular plate of the ethmoid bone with extension to the nasal cavity. The diagnosis and management of this unusual lesion, as well as the histopathology and the imaging characteristics are reviewed. We also review the previously reported cases of benign osteoblastomas of different origin, with nasal cavity involvement.

Ectopic internal carotid artery presenting as an oropharyngeal mass

Ectopic internal carotid artery (ICA) is a very rare variation. The major congenital abnormalities of the ICA can be classified as agenesis, aplasia and hypoplasia, and they can be unilateral or bilateral. Anomalies of the neck artery may be vascular neoplasms or ectopic position. Carotid angiograms provide absolute confirmation of an aberrant carotid artery, while EcoColorDoppler (ECD) gives also important information about the evaluation of carotid vassels. Nevertheless Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) of the neck provide spatial information about the adjacent pharyngeal anatomy and are less invasive than angiogram. Injuries to the ICA during simple pharyngeal surgical procedures can be catastrophic due to the risk of massive bleeding. We report a case of a 56 year-old male patient suffering from dysphagia associated with aberrant ICA manifesting itself as a pulsative protruding of the left lateral wall of the oropharynx.