The corticospinal tract in amyotrophic lateral sclerosis: an MRI study

Cortical motor neurone loss and corticospinal tract (CST) degeneration are typical of amyotrophic lateral sclerosis (ALS). It is a matter of debate whether qualitative assessment of the CST by MRI is useful in the diagnosis. It is also an open question whether quantitative determination of the T2 relaxation times can improve its value. Signal intensity along the CST on 14 consecutive slices was assessed using arbitrary visual rating on double-echo T2-weighted and proton-density spin-echo images of 21 patients with ALS and 21 age- and sex-matched controls. T2 was determined quantitatively. On the T2-weighted images the patients' ratings did not differ from that of controls. The T2 of patients and controls showed no statistical difference in any slice. There was no correlation between T2 and patient age, duration of the disease, or predominant bulbar, lower or upper motor neurone signs. The only correlation between MRI findings and disease was on the proton-density images: all cases in which the CST was poorly seen were controls; a clearly high-signal CST was seen only in the patients. High conspicuity of the CST was thus specific but not sensitive for the diagnosis of ALS. T2-weighted images and measurement of T2 were not useful for diagnosis.

Visualization of vascular guidewires using MR tracking

MR tracking of a vascular guidewire sized for a .035-inch (.89-mm) catheter lumen was performed. The guidewire was actively tracked by incorporation of a miniature radiofrequency (RF) receive coil built into its tip. After in vitro validation, simultaneous tracking of the guidewire and a catheter was performed in the aortic and abdominal vessels of a swine at 1.5 T. The ability to track such a small device and the ability to simultaneously track multiple devices are significant steps towards vascular interventions under MR guidance.

Parkinson's disease and depression: evidence for an alteration of the basal limbic system detected by transcranial sonography

OBJECTIVES

Depression is a frequent symptom in Parkinson's disease. Compelling evidence suggests a role of the brainstem in the control of mood and cognition. In patients with unipolar depression transcranial sonography (TS) studies have shown structural alteration of the mesencephalic brainstem raphe which could suggest an involvement of the basal limbic system in the pathogenesis of primary mood disorders. The objective of the present study was to evaluate whether a similar alteration could be found in depressed patients with Parkinson's disease using TS.

METHODS

Thirty patients with Parkinson's disease and 30 age and sex adjusted controls were examined by TS. Raphe echogenicity was rated semiquantitatively. The severity of motor symptoms and depression was rated using standard research instruments.

RESULTS

Raphe echogenicity was significantly reduced in depressed patients with Parkinson's disease compared with nondepressed patients with Parkinson's disease and control subjects. Raphe echogenicity correlated negatively with degree of motor impairment, and differences in raphe echo between depressed and non-depressed patients with Parkinson's disease were upheld when motor impairment was controlled for.

CONCLUSION

These preliminary findings suggest that, as in unipolar depression, a morphological alteration of the brainstem raphe might be involved in the pathogenesis of depression in Parkinson's disease. This raphe alteration may reflect involvement in the basal limbic system in the pathogenesis of secondary depression. This concept is in line with current knowledge on the pathogenesis of both depression in Parkinson's disease and primary depressive disorders.

MRI T2 relaxation times of brain regions in schizophrenic patients and control subjects

In this MRI investigation T2 relaxation times were studied in schizophrenic patients compared to normal control subjects. Approximate T2 relaxation times were calculated using signal intensity at two echo times in several brain regions of 25 male schizophrenic patients and 25 age-matched, normal male control subjects. The schizophrenic patients showed significantly longer T2 relaxation times as compared to normal control subjects in the left anterior column of the fornix. This is a small structure, prone to partial volume effects and this may account for these findings. There was a trend towards longer T2 times in the left frontal cortex and shorter T2 times in [corrected] right temporal cortex in schizophrenic patients as compared to control subjects. There were right/left differences in relaxation times within each group. In both patients and control subjects, frontal lobe white matter T2 was longer on the right than on the left side. This finding is probably due to brain asymmetry and unrelated to the presence or absence of psychiatric illness. In schizophrenic patients only the left temporal cortex showed longer T2 times than the right side. This observation could indicate left sided temporal lobe pathology in schizophrenia.

[Cerebral cavernomas--clinical aspects and therapy]

Cavernomas are congenital cerebrovascular hamartomas which occur sporadic or familial. They are comprised of multiple sinusoidal spaces, filled with blood, without enlarged arterial feeders and draining veins. They occur in an estimated 0.4 to 0.5% of the population, with male and female patients equally affected and all ages represented. Lesions are singular or multiple (up to 20%) in the same patient and occur all over the central nervous system. Clinical representation is characterized by cross intracranial hemorrhage, seizures and focal neurological deficits. Unspecific symptoms, like headaches, vertigo and tinnitus were present in 25 to 30% of the patients. Asymptomatic cavernomas could be detected in up to 20% of the cases. The natural course revealed an annual risk of bleeding (0.6%) and a risk of developing epilepsy (1.5%). Microsurgical resection of a symptomatic lesion is the first choice of treatment. There is no mortality and the morbidity after resection of superficial cavernomas is below 5%. Deep seated cavernomas revealed a higher risk of postoperative neurological deficit. Therefore indication of operative removal in deep seated cavernomas should be carefully weighted up to the risk of natural course and generally neurological and radiological control is favoured. Radiosurgery is only indicated in progressively symptomatic cases which are surgical inaccessible.

Clinical, morphological, biochemical, and neuroradiological features of mitochondrial encephalomyopathies. Presentation of 19 patients

Nineteen patients (9 females, 10 males) with mitochondrial encephalomyopathies (ME) were studied. The diagnosis was established according to clinical and histopathological criteria. Leading clinical features were chronic progressive external ophthalmoplegia (CPEO) and muscle weakness in 95% of the patients. Pigmentary retinopathy was seen in 63%, and was always associated with CPEO. Hypacusis was present in 47% and cerebellar ataxia in 63% of patients. Clinical or electrophysiological signs of involvement of the central nervous system (CNS) were found in 21% of the patients. In muscle biopsy ragged red fibers were the predominant histopathological findings (100% of the patients), while COX-negative fibers were seen in 74%, deletions of the mitochondrial DNA in 42%, and defects of the respiratory chain in 32% of the patients. Increased blood lactate levels were found in 79% of the patients. Needle electromyography revealed myopathic features in 74%, features of denervation in 16%, and was normal in the remainder. Imaging studies showed cerebral atrophy in 58%, cerebellar atrophy in 16%, and hyperintense lesions of the white matter, pyramidal tract or extrapyramidal system in 16% of the cases. It is concluded that the clinical manifestations of ME can be very variable. Diagnosis of ME should be always considered in young patients presenting with CPEO and muscle weakness. In most cases, diagnosis can be made by a few selected investigations, while detection of genetic abnormalities may lead to the diagnosis in the remaining cases.

Ophthalmoplegia plus: clinical relevance of magnetic resonance tomogaphy findings

The diagnostic value of magnetic resonance imaging (MRI) in patients with ophthalmoplegia plus was evaluated. Twenty patients in whom the diagnosis of opthalmoplegia plus was clinically and histochemically established underwent magnetic resonance and electrophysiological studies. Three types of neuroradiological abnormalities were found in 14 patients: (1) cerebral and/or cerebellar atrophy (n = 11), (2) hyperintense lesions of the white matter or pyramidal tract (n = 2), or (3) both (n = 1). The diagnostic yield of MRI was low, since clinically or electrophysiologically manifest lesions were missed in 4 cases and the pathological findings were non-specific, since they are seen in several demyelinating diseases. Our results suggest that MRI provides no additional information in patients with manifest ophthalmoplegia plus. We conclude that clinical presentation and evidence of ragged red fibers are the cornerstones in diagnosis of ophthalmoplegia plus.

Guidewire antennas for MR fluoroscopy

Before MRI can be used for guiding vascular interventions, the problem of dependably visualizing guidewires must be solved. Ideally, the position and curvature of the tip of the guidewire should be visible to facilitate steering through the vascular system. In this paper, various antennas are described that can be incorporated into a guidewire tip. These antennas allow the guidewire to be visualized with high contrast. Computer simulation and experimental evidence are presented showing the value of adding a passive MR signal source, with a short T1, internal to the coil. The internal source increases the available signal, narrows the apparent width of the guidewire, and allows the use of fast imaging sequences.

Arachnoid cysts associated with subdural hematomas and hygromas: analysis of 16 cases, long-term follow-up, and review of the literature

OBJECTIVE

Subdural hematomas and hygromas are infrequently encountered complications of arachnoid cysts of the middle cranial fossa and are particularly rare with cysts of other regions. Reports in the literature focus on casuistic observations. Therapeutic recommendations often include fenestration or extirpation of the cyst wall, in addition to evacuation of the space-occupying lesion. This study evaluates the results of and rationale for a more conservative approach, usually without cyst removal.

METHODS

Sixteen cases of complicated arachnoid cysts, from a total of 658 patients with subdural hematomas or hygromas, were analyzed retrospectively together with 75 other cases reported in the literature. Additionally, 94 magnetic resonance imaging scans from 89 patients with untreated arachnoid cysts, from a total of 11,487 examinations, were reviewed for signs of hemorrhagic complications.

RESULTS

Arachnoid cysts of the middle cranial fossa were found in 2.43% of patients with chronic subdural hematomas or hygromas. This indicated a fivefold greater prevalence of arachnoid cysts, compared with our magnetic resonance imaging-examined patient group. Only two patients with untreated cysts showed signs of hemorrhage in magnetic resonance imaging scans. An excellent or good therapeutic result was achieved with evacuation of the subdural fluid by drainage or craniotomy in 13 cases and with conservative treatment in two cases. Only one patient underwent additional fenestration of the cyst wall. No additional symptoms from the arachnoid cysts occurred in a follow-up period of up to 14 years after therapy.

CONCLUSIONS

We do not generally consider it necessary to perform cyst diversion or fenestration at the time of drainage of a hematoma or hygroma in previously asymptomatic arachnoid cysts.

Fistula of stapes footplate caused by pulsatile cerebrospinal fluid in inner ear malformation

Congenital malformations of the inner ear are well described, though the combination with cerebrospinal fluid (CSF) leaks remains controversial. In this paper a case of a bilateral Mondini malformation with a CSF otorrhea on one side is reported. The malformed stapes contains a perforation in the middle of the footplate and associated thinning analogous to a pothole in a mountain stream. The histological findings support the hypothesis of pulsatile flow of CSF as origin of the perforation of the footplate.

MR imaging-guided intravascular procedures: initial demonstration in a pig model

With use of an open 1.5-T magnetic resonance (MR) imager and a tracking catheter, the authors successfully placed the catheter into the left or right sacral artery in pigs. The tracking catheter comprised a 5.3-F percutaneous transluminal angioplasty catheter with a small copper radio-frequency coil in its tip. With use of the coil as an antenna, the catheter tip position was projected in real time onto MR angiography road maps in two planes. Guidance of placement of the catheter with the MR angiography road maps allowed successful embolization, balloon occlusion, and transjugular intrahepatic puncture of the portal system. Specialized catheters can be tracked in vivo to allow MR guidance in intravascular interventional procedures.

The fornix of the human brain: evidence of left/right asymmetry on axial MRI scans

This article reports the observation that there is a left/right asymmetry of the anterior columns of the fornix in the human brain. This asymmetry is present in the position of the two columns of the fornix in relation to the septum pellucidum. The left columna fornicis was found to be located caudal to the right, and this can be readily visualized on axial MRI scans. This difference was seen in most of the subjects, but in some subjects there was no left/right-difference and in a few the asymmetry was inverse. The asymmetry of the fornix with respect to the anterior-posterior axis was independent of the well-known dissimilar lateral ventricular volumes. However, the left/right difference in the position of the fornix was evident in subjects with or without differences in ventricular volumes. This suggests that the mechanism underlying the development of asymmetry of the fornix is independent of the mechanism leading to ventricular asymmetry. So far, no functional relevance has been ascribed to such differences in location. The finding is gaining interest in connection with recent reports of asymmetries in hippocampal subfields. Studies of fornical lesions should therefore give attention to possible side-to-side differences.

Comparison of transcranial sonography, magnetic resonance imaging, and single photon emission computed tomography findings in idiopathic spasmodic torticollis

Various lines of evidence suggest that the basal ganglia and thalamus are involved in the pathogenesis of idiopathic dystonia, but unfortunately neuroradiological and pathological data are sparse and controversial. In this study, we have examined 10 patients with spasmodic torticollis by neuroimaging techniques, including transcranial sonography (TS; n = 10), conventional (n = 10) and diffusion-weighted (n = 5) magnetic resonance imaging (MRI), and single photon emission computed tomography (SPECT; n = 10), employing [123I]iodobenzamide (IBZM) as a ligand with a high affinity to the D2 receptor. In seven patients, TS showed small hyperechogenic lesions in the medial segments of the lentiform nucleus contralateral to the side of head deviation. In accordance with the site of TS abnormalities, diffusion-weighted MRI displayed a hyperintense lesion in only one patient, while standard MRI of this area was normal in all patients. SPECT revealed a slight but statistically nonsignificant reduction of IBZM tracer uptake in an area corresponding to the dorsal portions of the striatum in 9 of the 10 patients. TS findings support the hypothesis that structural alternations of the pallidothalamic circuit contralateral to the side of head deviation are involved in the pathogenesis of idiopathic spasmodic torticollis. TS may be more sensitive in detecting basal ganglia alterations than MRI.

Is computerized tomography ventricular abnormality related to cycloid psychosis?

Twenty-eight psychiatric patients with computerized tomography (CT) findings of ventricular abnormality most likely to result from prenatal/perinatal lesions (VA group) were compared to 28 sex- and age-matched psychiatric patients with normal neuroradiological findings (NCT group). The neuroradiological rater was blind to clinical psychiatric diagnoses and, vice versa, clinical diagnoses were established without knowledge of neuroradiological findings. A polydiagnostic approach (DSM-III-R, ICD-10, Leonhard Classification) was used for psychiatric diagnostic workup. Significantly more patients with cycloid psychoses (according to Leonhard's original description) were found in VA as compared to NCT patients. According to DSM-III-R and ICD-10, VA and NCT groups did not differ significantly regarding diagnostic distribution. Ventricular abnormalities that may reflect sequels of birth complications and/or adverse events during pregnancy may constitute one of the risk factors for developing cycloid psychosis as originally described by Leonhard.

Interobserver agreement in assessing early CT signs of middle cerebral artery infarction

PURPOSE

To assess the reliability of detecting signs of hemispheric infarction on CT scans obtained within 6 hours of the onset of symptoms.

METHODS

A neuroradiologist selected 12 normal and 33 abnormal CT studies showing the hyperdense middle cerebral artery sign (HMCAS) (n = 10), brain swelling (n = 22), and parenchymal hypodensity (n = 33) from two series of 750 patients with recent onset of middle cerebral artery stroke. These selections served as the reference source for a nonblinded analysis of the initial and follow-up CT scans. Six neuroradiologists then reviewed the CT scans twice, first blinded then not blinded to clinical symptoms. They assessed the signs of infarction for each hemisphere separately and estimated the volume of abnormal parenchymal hypodensity in increments of 20% within the territory of the middle cerebral artery.

RESULTS

Unblinding the reviewers did not change interobserver agreement significantly. The chance adjusted agreement was moderate to substantial: kappa = .62 (95% confidence interval [CI], .46 to .78) and kappa = .57 (95% CI, .33 to .81) for the HMCAS of the right and left hemisphere, respectively; kappa = .59 (95% CI, .47 to .71) and kappa = .56 (95% CI, .38 to .74) for focal brain swelling of the right and left hemisphere, respectively; and kappa = .58 (95% CI, .50 to .66) and kappa = .55 (95% CI, .32 to .67) for parenchymal hypodensity of the right and left hemisphere, respectively. Weighted kappa was .65 and .57 for the estimation of the hypodense tissue volume in the right and left hemisphere, respectively. Agreement with the reference source ranged from 73% to 93% for all variables and both hemispheres.

CONCLUSION

Even with no clinical information, neuroradiologists can assess subtle CT signs of cerebral infarction within the first 6 hours of symptom onset with moderate to substantial interobserver agreement.

[Radiofrequency catheter ablation of an accessory atrioventricular conduction pathway with persistent left superior vena cava and hypertrophic cardiomyopathy]

A 43-year-old man with a 30-year history of WPW-syndrome and a hypertrophic cardiomyopathy developed acute heart failure after onset of atrial fibrillation with fast antegrade conduction, which could be converted to sinus rhythm with antiarrhythmic medication. Catheterization of the coronary sinus during EP testing demonstrated a persistent left superior vena cava. The accessory pathway could be localized at the orifice of an atypical epicardial vein. It was successfully abolished after subvalvular placement of the electrode catheter in the left ventricle. This constellation indicates a combined defect during the regression of the sinus venosus to the sinus coronarius with persistence of conducting muscle fibers. Successful RF ablation procedure provides an obvious risk reduction as a result of a lower frequency of atrial fibrillation and the eliminated risk of ventricular fibrillation due to rapid conduction via an accessory pathway. Beyond that, harmless therapeutic treatment of hypertrophic cardiomyopathy with a calcium-channel-blocker (verapamil type) can follow RF ablation.

[Psychiatric sequelae of craniocerebral trauma--a review of the literature]

In a brief review psychiatric aspects of head-injured patients are discussed. The topic is put into a historical perspective. Examples of recent developments in head-trauma research are given. Differentiation between focal and diffuse brain injury is suggested to be of clinical relevance. Little is known as yet about the neuropsychologic and psychiatric sequelae of diffuse axonal injury to the brain.

Structural basis of light harvesting by carotenoids: peridinin-chlorophyll-protein from Amphidinium carterae

Peridinin-chlorophyll-protein, a water-soluble light-harvesting complex that has a blue-green absorbing carotenoid as its main pigment, is present in most photosynthetic dinoflagellates. Its high-resolution (2.0 angstrom) x-ray structure reveals a noncrystallographic trimer in which each polypeptide contains an unusual jellyroll fold of the alpha-helical amino- and carboxyl-terminal domains. These domains constitute a scaffold with pseudo-twofold symmetry surrounding a hydrophobic cavity filled by two lipid, eight peridinin, and two chlorophyll a molecules. The structural basis for efficient excitonic energy transfer from peridinin to chlorophyll is found in the clustering of peridinins around the chlorophylls at van der Waals distances.

Cerebellar arachnoid cyst in a firesetter: the weight of organic lesions in arson

A 52-year-old female patient was accused of arson; the patient had had an arachnoid cyst of the cerebellar vermis. Even after surgery, she showed marked instability of mood and pseudologia fantastica, but did not suffer from cognitive impairment. Possible associations of the presence of this cerebellar arachnoid cyst and behavioral disturbances are discussed.

Characterization of transmembrane domains 6, 7, and 8 of MalF by mutational analysis

Oligonucleotide mutagenesis was used to isolate mutations in membrane-spanning segments 6, 7, and 8 of MalF. MalF is a cytoplasmic membrane component of the binding protein-dependent maltose transport system in Escherichia coli. The current structural model predicts eight transmembrane domains for MalF. Membrane-spanning segments 6, 7, and 8 of MalF flank or are part of the EAA-X3-G-X9-I-X-LP consensus region present in the cytoplasmic membrane subunits of the bacterial ABC transporter superfamily members. Mutations with two novel phenotypes with respect to substrate specificity of the maltose transport system were isolated. One mutant grew on minimal maltose media but not on media containing either maltoheptaose or maltoheptaose plus maltose and was thus termed dextrin dominant negative. The other class of mutations led to a maltose minus but maltoheptaose plus phenotype. Nine of the isolated mutations leading to changes in substrate specificity were tightly clustered on one face of the postulated transmembrane helix 6. A similar clustering of mutations was detected in transmembrane domain 7. The majority of mutations in membrane-spanning segment 7 led to a protease-sensitive or a conditional phenotype with respect to MalF function or both. Mutations in transmembrane domain 8 appeared to be more randomly distributed. The majority of mutations in membrane-spanning segment 8 caused a Mal+ Dex- phenotype. Six Mal+ suppressor mutations isolated to two mutations in transmembrane domain 7 changed amino acid residues in membrane-spanning segment 6 or 8.

Median corpectomy in cervical spondylotic multisegmental stenosis

Cervical median corpectomy as an alternative to laminoplasty and laminectomy has been suggested as an effective treatment for cervical spondylotic myelopathy (CSM) in cases of multisegmental spondylotic stenosis. We report on our experience with this procedure with particular reference to neurological outcome and complications. Median corpectomy was performed in 17 cases (3 female, 14 male; mean age 59 yrs, (41-80 yrs.) with cervical myelopathy (CM) and radiologically diagnosed multisegmental spondylotic stenosis and spinal cord compression seen on MRI. The degree of stenosis was determined by means of the modified Pavlov's index (ratio between spinal canal width at the level of the intervertebral disc and the diameter of the vertebral body itself). 3/17 patients suffered from acute, 4/17 from subacute and 10/17 from chronic CM. Single level corpectomy was performed in 9 cases, one and a half vertebrae were removed in 2 cases and dual level corpectomy was performed in the remaining 6 cases. All patients received an autologous bone graft and AO - anterior plate stabilization or were stabilized as described by Morscher. Postoperative follow - up was possible in 16/17 cases over a mean time of 13.5 months. Myelopathy was graded according to Nurick's scale. Postoperatively, 12% with chronic CM improved by two grades, 38% (2 pts, with acute, 3 with subacute and 1 with chronic CM) improved by one grade. The other patients remained stable, none showed worsening of their myelopathy. Paresis improved in 92%, sensory deficits in 69%, spasticity in 73%, pain in 60%, and vegetative disturbances in 100% of all patients presenting these preoperative symptoms respectively. One patient died due to esophageal perforation and subsequent lethal mediastinitis caused by screw loosening 4 months following surgery and after initial neurological improvement. 4 other patients experienced screw loosening, three with acataposis, one remained clinically asymptomatic with concomitant graft displacement in two of these. One patient had to be re-operated due to a hematoma at the iliac crest and 2 suffered from a pelvic fracture of the spina iliaca at the site of graft removal. With respect to the neurological improvement, especially to the motor function and spasticity, median corpectomy can be regarded as an effective procedure in selected cases with cervical myelopathy, even when treatment related complications are taken into consideration.

[Acute organic psychosis after malaria tropica]

Neuropsychiatric complications in the course of plasmodium falciparum infection are usually summarized as cerebral malaria. Heterogeneous clinical symptoms, different courses and inconstant parasitemia, however, suggest different pathogenic mechanisms. We report a case of an acute symptomatic psychosis occurring two weeks after successful therapy of a primary manifestation of plasmodium falciparum infection. The diagnosis of meningoencephalitis was based on lymphocytic pleocytosis of cerebrospinal fluid and hyperintense lesions in cranial magnetic resonance imaging. Due to the lack of plasmodium falciparum parasitemia and of serological evidence of viral infection a final diagnosis was not possible. Considering the pertinent literature, an immune-mediated complication of plasmodium falciparum infection (acute disseminated encephalomyelitis, ADEM) appears to be more probable than a direct viral or plasmodium CNS infection. We propose to reverse the term cerebral malaria for the cases with direct pathogenic influence of plasmodium falciparum, and to distinguish it from cases with possible immune-mediated pathogenesis.