Epilepsy: structural or functional?
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Brain Diseases↗
Biomedical subjects
J M Stevens
Publications and source records attributed to J M Stevens.
Post-renal transplant distal limb bone pain. An under-recognized complication of transplantation distinct from avascular necrosis of bone?
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Adult↗
Postoperative arachnoiditis diagnosed by high resolution fast spin-echo MRI of the lumbar spine.
Chronic adhesive arachnoiditis is cited as an important cause of recurrent pain and disability after extradural lumbar disc surgery. Myelography using oil-based or ionic water-soluble contrast media was a major contributing factor, and it was not possible to distinguish the prevalence of arachnoiditis probably due to surgery alone. Today it should be possible to make this distinction, which was the purpose of this study. Using high-resolution MRI in 129 patients symptomatic at least 1 year after surgery, a prevalence of arachnoiditis of 20% was found, which dropped to 3% when patients who had undergone oil-based myelography were excluded. Arachnoiditis was diffuse in 88% and focal in 12%. When oil-based media were involved it was focal in 13%, and when not, in one of three cases. It was concluded that arachnoiditis does occur after extradural lumbar disc surgery independently of the use of some myelographic contrast media, and that it may be diffuse or confined only to the operated level. Its prevalence was estimated at 4.6%, four cases focal and two cases diffuse. The causes and clinical significance can only be the subject of speculation.
Adult↗
Iodixanol in intra-arterial cerebral digital subtraction angiography: a comparison with iohexol.
We randomised 86 patients undergoing intra-arterial cerebral digital subtraction angiography (IADSA) to receive iodixanol (Visipaque; Nycomed, Oslo, Norway) 150 mgI/ml or iohexol (Omnipaque; Nycomed) 140 mgI/ml. The efficacy and safety of these two contrast media were compared: efficacy by evaluating the diagnostic information and radiographic density yielded by the angiograms, safety by recording all discomfort connected with the injections, and all adverse events up to 24 h after the investigation. Diagnostic information was optimal in all patients and the overall radiographic density optimal in all but one (iohexol) (P = 0.49). A feeling of warmth, the only discomfort reported, was experienced by 43% and 54% of patients receiving iodixanol and iohexol, respectively (P = 0.26). Two patients in the iodixanol group and five in the iohexol group reported one adverse event (nausea, dizziness, visual disturbance or paraesthesiae) (P = 0.30); all were of mild severity except for one moderate adverse event in each group. Iodixanol 150 mgI/ml and iohexol 140 mgI/ml were demonstrated to be suitable for IADSA, with no clinically or statistically significant differences in efficacy, discomfort or adverse events.
Adult↗
Craniovertebral junction anomalies in inherited disorders: part of the syndrome or caused by the disorder?
Patterns of skeletal abnormality at the craniovertebral junction in the normal population and in syndromes such as Down, Morquio etc, are compared and the recent embryological data and comparative anatomy reviewed. The authors' view based on their own clinical and radiological experience is that the os odontoideum is the product of excessive movement at the time of ossification of the cartilaginous dens and is exactly analogous to the unfused Type II odontoid fracture. True hypoplasia of the odontoid peg is part of a wider segmentation defect associated with Klippel Feil, occipitalised atlas and/or basilar invagination; it is hardly ever associated with instability.
Animals↗
Abnormalities of gyration, heterotopias, tuberous sclerosis, focal cortical dysplasia, microdysgenesis, dysembryoplastic neuroepithelial tumour and dysgenesis of the archicortex in epilepsy. Clinical, EEG and neuroimaging features in 100 adult patients.
Cerebral cortical dysgenesis (CD) is a heterogeneous disorder of cortical development and organization commonly associated with epilepsy, with a variety of subtypes. We reviewed the clinical, EEG and neuroimaging features in 100 adult patients with CD. There were 39 men and 61 women with a median age of 27 years (range 15-63 years). All patients were referred because of medically refractory epilepsy. Median age at seizure onset was 10 years (range 3 weeks to 39 years); in 30 patients, onset was in adulthood. The epilepsy was classified as generalized in 16 patients and localization-related in 84. Of the latter, the epileptic syndromes in decreasing frequency were frontal (32%), temporal (31%), parietal (14%) and occipital (7%). Only 15% of patients had a history of status epilepticus. Prenatal/perinatal problems were reported in 32 patients but these were severe in only four: exposure to drugs (three) and infection (one) during the first trimester. Delayed developmental milestones were seen in 10%, mental retardation in 9%, additional congenital abnormalities in 4% and neurological deficits in 14% of patients. Diagnosis of CD was based on neuroimaging in 70, pathology in four and both methods in the remaining 26. The following subcategories were identified: agyria/diffuse macrogyria (four patients), focal macrogyria (16), focal polymicrogyria (one), focal macrogyria/polymicrogyria associated with a cleft (11), minor gyral abnormalities (seven), subependymal grey matter heterotopia (20), bilateral subcortical laminar grey matter heterotopia (eight), tuberous sclerosis (five), focal cortical dysplasia/microdysgenesis (seven) and dysembryoplastic neuroepithelial tumours (DNT) (21). Sixty-eight percent of patients had normal CT and 19 out of 36 patients had normal previous conventional MRI. MRI-based hippocampal volume measurements in 47 patients revealed ratios (smaller: larger hippocampus) of < 0.90 in 16, 0.90-0.94 in 14 and > or = 0.95 in 17 patients. EEGs were normal in only five patients. Alpha rhythm was preserved in 78 patients, including one patient with bilateral posterior macrogyria. Localized polymorphic slow activity was present in 43 patients. Five of 68 patients with focal/unilateral CD had only bilateral independent/synchronous spiking and 14 out of 32 with diffuse/bilateral CD only focal/unilateral spiking. In 60 patients with nondiffuse CD or with abnormal gyration or DNT, the epileptiform abnormalities were less extensive than coextensive with the lesion in 28, more extensive than and overlapped the lesion in 18 and remote from the lesion in five; nine patients did not have epileptiform abnormalities. There was poor correlation between the epileptic syndromes and EEG abnormalities and the location/extent of CD as defined by MRI and pathology.(ABSTRACT TRUNCATED AT 400 WORDS)
Adolescent↗
Widespread cerebral structural changes in patients with cortical dysgenesis and epilepsy.
Cerebral cortical dysgenesis (CD), as revealed by MRI is the second commonest cause of medically refractory chronic partial epilepsy. Surgical treatment is often disappointing in these cases. This has been attributed to the probable diffuse nature of the condition but proof of this in the human brain is lacking. We have quantitatively analysed MRI scans of 30 neurologically normal control subjects and 18 patients with CD, examining the regional distribution of grey and subcortical matter volumes. In 15 out of the 18 patients, we have demonstrated abnormalities of this distribution beyond the margins of the visualized lesion. Nine out of 10 patients with dysgenetic lesions visualized only in one hemisphere had volumetric abnormality in the apparently normal contralateral hemisphere. These abnormalities were not visible on reinspection of the MRI scans. Such abnormalities were not found in 10 patients with isolated hippocampal sclerosis (HS) although the history of generalized seizure activity and duration of epilepsy did not differ between the two groups of patients. Thus there is evidence for the existence of extensive structural disorganization outside visually identified focal lesions in the brains of patients with CD and chronic partial epilepsy. This disruption is not due to the effects of the epilepsy and must instead be associated with its cause. Possible mechanisms producing the abnormalities are discussed. The methodology described may be applied to other cortical diseases.
Adult↗
Superficial siderosis of the central nervous system.
There have been 87 cases of superficial siderosis of the CNS reported in the world literature and 63 cases had developed the clinical syndrome with sufficient details to be reviewed. It is a distinct clinical syndrome characterized by sensorineural deafness (95%), cerebellar ataxia (88%) and pyramidal signs (76%). Other features include dementia (24%), bladder disturbance (24%), anosmia (at least 17%), aniscoria (at least 10%) and sensory signs (13%). Less frequent features are extra-ocular motor palsies, neck or backache, bilateral sciatica and lower motor neuron signs (5-10% each). Males are more often affected than females (3:1). The age of onset ranged from 14 to 77 years, age at death from 29 to 78 years and duration until death from 1 to 38 years excluding premature death due to the underlying cause or as a result of surgery. Up to 27% become bed bound at 1-37 years from the first symptom due to either cerebellar ataxia, a myelopathic syndrome or both. Symptomatic subarachnoid haemorrhage occurred in 37% and the CSF was haemorrhagic and/or xanthochromic in 75%. It is now accepted that superficial siderosis is due to chronic subarachnoid haemorrhage and a source of bleeding has been reported in 54% of cases; it was either due to dural pathology (47%) including a CSF cavity lesion or cervical root lesion, a vascular tumour (35%) or a vascular abnormality (18%). Arguments are presented that the remaining cases were also due to chronic haemorrhage and that there is no evidence for a non-haemorrhagic form of superficial siderosis. There have been 14 incidental cases diagnosed by MRI or at post-mortem with no symptoms attributable to superficial siderosis during life, supporting the notion of a pre-symptomatic phase to the illness. In 22 patients who had developed the syndrome, the duration of this pre-symptomatic phase could be calculated and ranged from 4 months to 30 years with an average of 15 years. At present the most promising treatment for superficial siderosis is surgical ablation of the bleeding sources.
Adolescent↗
Imaging of the spinal cord.
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Diagnostic Imaging↗
Bilateral lesions of CA1 and CA2 fields of the hippocampus are sufficient to cause a severe amnesic syndrome in humans.
A patient is reported in whom a classic amnesic syndrome developed as a result of repeated episodes of cerebral ischaemia, accompanied by seizures. The amnesia was very severe for both old and newly acquired memories and the critical lesions defined by MRI were circumscribed areas confined to CA1 and CA2 fields of both hippocampi.
Aged↗
High resolution magnetic resonance imaging in adults with partial or secondary generalised epilepsy attending a tertiary referral unit.
In the past the underlying structural abnormalities leading to the development of chronic seizure disorders have usually only been disclosed by histological examination of surgical or postmortem material, due to their often subtle nature that was beyond the resolution of CT or early MRI. The MRI findings in 341 patients with chronic, refractory epilepsy attending The National Hospital for Neurology and Neurosurgery and Chalfont Centre for Epilepsy are reported. Studies were performed on a 1.5 Tesla scanner with a specific volumetric protocol, allowing the reconstruction of 1.5 mm contiguous slices throughout the whole brain. Direct visual inspection of the two dimensional images without the use of additional quantitative measures showed that 254/341 (74%) were abnormal. Twenty four (7%) patients had more than one lesion. The principal MRI diagnoses were hippocampal asymmetry (32%), cortical dysgenesis (12%), tumour (12%), and vascular malformation (8%). Pathological confirmation was available from surgical specimens in 70 patients and showed a very high degree of sensitivity and specificity for the different entities. The advent of more widely available high resolution MRI should make it possible to identify the underlying pathological substrate in most patients with chronic partial epilepsy. This will allow a fundamental reclassification of the epilepsies for both medical and surgical management, with increasing precision as new methods (both of acquisition and postprocessing) are added to the neuroimaging battery used in clinical practice.
Adolescent↗
Cerebral achromatopsia as a presentation of Trousseau's syndrome.
A 67-year-old man developed a sudden onset of achromatopsia. Magnetic resonance imaging showed occipital lobe infarction. Repeated episodes of neurological deficit referable to the posterior circulation initially suggested an embolic source, but subsequently proved to be due to a coagulopathy related to a carcinoma of the bladder. This has implications for the management of patients presenting with achromatopsia, and progressive or recurrent neurological episodes, and in particular the use of anticoagulation in this situation.
Aged↗
Fractal description of cerebral cortical patterns in frontal lobe epilepsy.
The convoluted pattern of normal cerebral cortex resists description by Euclidean geometry. However, subtle abnormalities often unrecognised in vivo may underlie a wide range of neurological disorders. Abnormalities of cortical morphology frequently characterise these lesions, and we applied fractal geometry in an attempt to quantify these abnormalities. We have demonstrated typical fractal scaling properties for the cortical-white matter interface on axial and coronal MR images, with a fractal dimension (Df) of 1.45 +0.06 (mean +1 standard deviation) in normal subjects. We have also applied this to 16 patients with frontal lobe epilepsy, a condition associated with subtle disruptions of the cortical ribbon, all of whom had no obvious abnormality on visual inspection of the images. Nine of these 16 had a Df < 1.27 (mean -3 standard deviations). A control group of 10 patients with temporal lobe epilepsy with a focal foreign tissue lesion (vascular or tumoural) all had Df in the normal range. Analysis of shape using this method identifies subtle abnormalities of the cortical ribbon, and has potential application to images of the human brain in a wide range of clinical and pathophysiological settings.
Adolescent↗
Methods for normalization of hippocampal volumes measured with MR.
PURPOSE: To investigate the use of six cerebral measures as correlates for hippocampal volumes and, therefore, to enable normalized absolute hippocampal volumes to be calculated via two correction processes. METHODS: Hippocampal volumes and six cerebral measures were estimated from MR data in 20 control subjects. Three of these measures (the cranial volume, the cerebral volume, and the midsagittal cranial area) were then applied to a group of 32 control subjects, and regression analysis was performed to investigate the linear relationship between hippocampal volume and each measure. Division of hippocampal volume by cerebral measure and correction via a covariance calculation enabled corrected absolute hippocampal volumes to be determined for 32 control subjects and 23 patients with temporal lobe epilepsy. RESULTS: Correction processes reduced the variance in absolute hippocampal volumes in control subjects and enabled abnormally small absolute volumes to be defined. Of 11 patients with unilateral volume ratio abnormalities, 8 had unilateral abnormally small absolute hippocampal volumes. Of 12 patients with normal volume ratios, 4 had bilateral abnormally small absolute hippocampal volumes. CONCLUSION: Correction processes can define absolute hippocampal volumes for correlation studies and may enable identification of unsuspected bilateral hippocampal volume loss.
Adult↗
Estimation of resection volumes in lesional epilepsy surgery.
An MR-based method for measuring resection volumes in lesional epilepsy surgery is described. The volume of the preoperative lesion, the resection cavity and, as a result, the volume of the brain surrounding the lesion resected during surgery have been calculated in 13 patients.
Adolescent↗
Nystagmus and joint position sensation: their importance in posterior occipitocervical fusion in rheumatoid arthritis.
It is widely believed that brain stem dysfunction and cranial nerve palsies in patients with rheumatoid arthritis (RA) are common and related to the vertical translocation of the odontoid process. In our database of 235 patients with seropositive RA and craniocervical junction involvement, we have found a very low incidence of such problems. Long tract signs were common, but loss of proprioception (joint position sensation) as the sole neurologic deficit was rare. Nystagmus was found to be associated with the tonsillar herniation of a Chiari 1 malformation and loss of joint position sensation with severe compression of the posterior aspect of the spinal cord at the craniocervical junction. The implications for posterior occipitocervical fusion, particularly by sublaminar wiring, are discussed.
Adolescent↗
Apparent cerebellar ectopia: a reappraisal using volumetric MRI.
Cerebellar ectopia, once considered rare, is apparently extremely common on magnetic resonance imaging (MRI). However, assessment of cerebellar position relative to the foramen magnum is usually made from thick sagittal sections and therefore may not be as reliable as sometimes believed. Volumetric MRI, acquired in the coronal plane with section thickness 1.5 mm, was used to assess the position of the cerebellum in 144 subjects who also had two-dimensional sagittal imaging using 5.0 mm thick sections. On these images, the frequency of cerebellar ectopia appeared to be 19% (27 cases), but volumetric coronal images indicated that the biventral lobules protruded below the foramen magnum in only 3 (2%), and the cerebellar tonsils lay well above in all cases. Hence the actual frequency of cerebellar tonsillar ectopia in this sample was zero. We concluded that cerebellar ectopia really is rare.
Adolescent↗