The relation between functional deficits, motor and sensory conduction times and MRI findings in syringomyelia

Opinions about the relation between the dimensions of the syrinx and the severity and distribution of symptoms in patients with syringomyelia are controversial. Therefore, this study investigates the relation of clinical symptoms, a disability score, quantified (1- and 2-dimensional) radiological findings (magnetic resonance imaging, MRI) and electrophysiological data (somatosensory and motor evoked potentials) in 22 patients with syringomyelia. There was a close relation between clinical symptoms and electrophysiological data. By both electrophysiological methods subclinical deficits could be detected. Furthermore, the results disclosed that the clinical symptoms, the degree of disability and the duration of the disease are not related to the dimensions of the syrinx or the electrophysiological results obtained by investigating the long ascending and descending spinal tracts of the lower limbs. Our findings suggest that, besides the syrinx, other factors not directly visible in the MRI are responsible for the development and progress of clinical symptoms.

Characteristic EEG findings in childhood moyamoya syndrome

Moyamoya syndrome-specific alterations of EEG recordings are only observed in children. These consist of a gradual frequency decrease and amplitude activation after hyperventilation. This is referred to as re-build-up phenomenon. Thus, a tentative diagnosis of Moyamoya syndrome in children can be based on the EEG finding. This should be radiologically confirmed by angiography.

[MRT of the hypophysis: spin echo 2D or gradient echo 3D?]

Diagnostic efficacy of T1-weighted 3D gradient-echo and 2D spin-echo pulse sequences in the detection of adenomas were evaluated in a ROC study of 50 patients. Sensitivity, specificity and accuracy did not differ significantly, but in direct comparison gradient-echo received a clear lower rating due to susceptibility artifacts, lower signal-to-noise ratio, and inferior periglandular contrasts. Additional lesions could not be reliably detected in gradient-echo imaging at 1 mm slice thickness. A substitution of 2D spin-echo imaging by gradient-echo sequences cannot be recommended at present.

Functional and morphological deficits in late-treated patients with homocystinuria: a clinical, electrophysiologic and MRI study

Seven late-treated patients between the ages of 10-30 years suffering from homocystinuria were examined clinically and electrophysiologically; four had MRI. The clinical examination showed extrapyramidal features and slight impairment of proprioception. Electrophysiological evaluation revealed normal results in the acoustic and central motor system; a minor, possibly vitamin B6 related, sensory neuropathy was detected by peripheral conduction studies. MR imaging showed small focal areas of gliosis in the white matter, generalized cortical atrophy in two patients, but only one small cortical infarct. No changes in the basal ganglia were detected. These results support the view that neurological signs and symptoms in patients suffering from homocystinuria are related to morphological findings, as well as pharmacological effects.

Multifactorial genesis of neuroradiological "leucoencephalopathies."

Three cases of neuroradiologically diagnosed "leucoencephalopathy" are reported. Histopathological examination disclosed Binswanger's encephalopathy in Case 1, congophilic angiopathy with secondary leucoencephalopathy in Case 2, and HIV encephalopathy with secondary white matter changes in Case 3. These three cases demonstrate the unspecificity of neuroradiological findings in "leucoencephalopathy".

Disturbed myelination in patients with treated hyperphenylalaninaemia: evaluation with magnetic resonance imaging

Cranial magnetic resonance imaging (MRI) was performed in nine treated adolescents with hyperphenylalaninaemia (HPA) in order to analyse possible changes in myelination. Three patients suffered from type I HPA, four from type II and two from type III (persistent HPA). Images were obtained with a 1.5 T unit using spin-echo-sequences. In all patients with type I or type II HPA, abnormal findings in the cerebral white matter were demonstrated including band-like and/or confluent patchy areas of high signal intensity predominantly in the peritrigonal region, with anterior and posterior periventricular extension and/or involvement of the subcortical white matter. The extent of MRI changes did not correlate with the initiation, duration or quality of dietary treatment. There was also no consistent relationship between electrophysiological changes and white matter abnormalities on MRI. Our findings suggest a disturbance of myelination in patients with treated HPA. These results correspond well with earlier neuropathological and biochemical studies in untreated patients.

[The use of rapid sequences in craniocerebral MR diagnosis]

MRI of the head is routinely performed with spin-echo sequences whereas gradient-echo sequences are still uncommon. Certain features of fast imaging sequences make them a promising tool for clinical investigations. The relative high signal-to-noise ratio/unit time demonstrates the usefulness of GE imaging as localising images. The extremely high contrast-flexibility is sometimes superior to SE imaging and may help to characterise structures and lesions. Flow dynamics are more clearly depicted than with SE sequences and lead to the dynamic evaluation of intracranial motion (CSF flow, blood flow). This information may be used in a special mode to achieve MR angiograms. Due to the very short repetition times, GE sequences are excellently suited to 3D application. This enables to reduce slice thickness to less than 1 mm with optional reconstructions in any virtual direction. In view of present developments in MR, GE imaging will be accepted in clinical diagnostic imaging in the near future.

[The MR tomographic findings in cranial manifestations of neurofibromatosis]

Twelve patients with central neurofibromatosis underwent MR examination of the head. Among these, chiasma glioma was the most common CNS tumour (6/12). Seven patients had multifocal areas of increased T2-signal without mass effect predominantly involving the region of the basal ganglia. No corresponding CT abnormalities were present. These lesions may represent multifocal dysplasia and seem to be characteristic of central neurofibromatosis.

[Characteristic EEG--findings in moyamoya syndrome in children: case report and overview]

Specific alterations of EEG tracings with Moyamoya syndrome are only observed in children. They consist in a gradual frequency decrease and amplitude activation after hyperventilation. This is referred to as re-build-up phenomenon. Thus, a tentative diagnosis of Moyamoya syndrome in children may be based on the EEG finding, to be radiologically confirmed by angiography.

[MR findings in patients with idiopathic panhypopituitarism]

High-resolution MR imaging was performed in seven patients with pituitary dwarfism and panhypopituitarism. In five cases MR-findings included absence of the infundibulum and of the normal intrasellar posterior pituitary bright spot, and the presence of a small nodule at the median eminence. The absence of diabetes insipidus in these patients and the signal characteristics of the nodule at the median eminence suggest that the latter may represent a functioning ectopic posterior pituitary lobe. This complex of findings was only observed in patients with complications in the perinatal period (breech delivery) and appears to be the end result of an ischemic or traumatic injury of the infundibular stem. The infundibular defect would explain both the permanent hormone deficiency of the anterior pituitary gland through a disruption of the hypothalamic-hypophyseal portal system and the absence of diabetes insipidus through an ectopic regeneration of the neurohypophysis at the median eminence.

Identification of sources of brain neuronal activity with high spatiotemporal resolution through combination of neuromagnetic source localization (NMSL) and magnetic resonance imaging (MRI)

The locations of the origin of wave M100 of the auditory evoked magnetic field in response to tone bursts of different carrier frequencies, obtained through dipole localization methods (DLM), were related to cerebral structures, displayed by coronal MRI (magnetic resonance imaging) tomograms of the respective subjects. This was done by displaying the landmarks which served as reference for the neuromagnetic measurements in MRI tomogram (reference plane). All calculated source locations project exactly onto the transverse temporal gyri (Heschl) in which the primary auditory cortex, the supposed origin of wave M100, is located. The results highlight the exceptional capabilities of a combination of these 2 non-invasive, high-resolution techniques for functional diagnosis.

Functional deficits of central sensory and motor pathways in patients with cervical spinal stenosis: a study of SEPs and EMG responses to non-invasive brain stimulation

The central conduction time of the descending and ascending fibers of the spinal cord were examined in patients with radiologically defined cervical spinal stenosis (antero-posterior diameter of the spinal canal less than 13 mm). Nineteen patients were examined, only 4 of whom showed clinical signs of spastic weakness or ataxia. The electromyographic response after non-invasive stimulation of the leg area of the motor cortex was delayed in 13 of the 15 clinically unaffected patients. The central latency (N21-P39) of the somatosensory evoked response after stimulation of the tibial nerve (tibialis SEP) was increased in 12 of the 15 individuals. The 4 patients with clinical signs showed abnormal latencies with both methods. The use of both techniques for the examination of the function of the spinal cord revealed increased latencies in the central motor and/or sensory pathways in all patients. The technique of non-invasive stimulation of the corticospinal system therefore provides an additional tool to detect and quantify subclinical and clinically apparent lesions in patients with defined cervical spinal stenosis.

[Function of the long spinal cord pathways in cervical spinal stenosis--an electrophysiologic study]

Cervical spinal stenosis is radiologically defined by a reduced inner diameter (X less than 13 mm) of the cord canal and in most cases etiologically connected with spondylosis. The following study describes the results of non-invasive assessment of the long ascending and descending spinal tracts in 12 patients. The long ascending spinal tracts were examined by spinal and cortical SEP after stimulation of the tibial nerve; for the assessment of the descending spinal tracts motor responses of the tibial anterior muscle were recorded after non-invasive stimulation of the motor cortex. Clinically symptomatic patients (N = 2) exhibited clear-cut functional motor and sensory deficits of the central pathways. In asymptomatic patients (N = 10) corticomotoneuronal latencies to the lower limbs were increased in 8 cases. In comparison, increased central sensory latencies were found in 9/10. In conclusion, the studies showed that the technique of non-invasive stimulation of the motor cortex may play a role in the detection of subclinical lesions of the long descending motor tracts due to a chronic mechanical irritation.

[Mycoplasma pneumoniae encephalitis]

Clinical, CT and, in one case, autopsy findings indicated a diagnosis of a severe necrotising encephalitis in two patients. Although usually herpes simplex virus is blamed for this form of encephalitis, it was possible to prove in these two patients that Mycoplasma was the causative agent of the disease. It is concluded that this organism can produce a serious disease in the central nervous system similar to that caused by herpes simplex.

[Intracranial forms of malignant lymphoma manifestations]

Approximately 10% of patients with malignant lymphoma will show neurological symptoms at some time during the course of their illness. In non-Hodgkin lymphoma, CNS involvement is more frequent than in Hodgkin's disease. Diffuse histiocytic and poorly differentiated lymphomas, bone marrow involvement, advanced tumor stage and hematogenous spread are particular risk factors. Invasion of the spinal canal is the most common type of CNS involvement. Intracranial lesions, which are comparatively rare, may present as intracerebral metastases, epi- or subdural masses or focal or diffuse leptomeningeal disease. Lymphomatous leptomeningitis usually cannot be demonstrated by CT. On the other hand, dural and cerebral parenchymal lesions are sometimes highly characteristic of lymphoma as a result of their features and location.

[Roentgen diagnosis of the medial part of the base of the skull]

The median section of the base of the skull offers many diagnostic problems in radiology. Findings of the plain radiographs and tomographs, of computed tomography and angiography are demonstrated in cases of space-occupying growths of the sella region, lesions of the fossa temporalis and of the region of the pyramid of the medulla oblongata, from a differential diagnostic viewpoint. Sequelae of traumas are discussed separately.