Biomedical subjects

W M Verduin

Publications and source records attributed to W M Verduin.

12 recordsLinked to original sources

PubMed2001

The value of electrophysiology results in patients with epilepsy and vigabatrin associated visual field loss.

PURPOSE: To determine the value of electrophysiological findings in patients with temporal lobe epilepsy and to relate these findings to the amount of concentric contraction of the visual field and the use of vigabatrin. METHODS: Electro-retinograms and electro-oculograms were done on 30 patients, operated for temporal lobe epilepsy. The patients were divided into three groups: (A) concentric contraction of the visual field associated with a history of vigabatrin medication (15 patients), (B) normal visual field with vigabatrin use (11 patients) and (C) normal visual field without vigabatrin medication (4 patients). RESULTS: Electrophysiological abnormalities were found in 50% of the patients in group A. The Arden ratio of the EOG was lowered in 57%. Abnormalities in the ERG were found: b-wave implicit time photopic F was prolonged (50%), b-wave amplitudes scotopic B (53%), C (73%) and G (50%) and photopic H (50%) were diminished. The amount of visual field loss and the total dose of vigabatrin used, showed only slight correlation with the ERG and EOG. The use of vigabatrin during the ERG and EOG recording in group A, gave a higher b-wave amplitude scotopic G in 64% of cases. The a-wave implicit times scotopic G (73%) and photopic G (59%) and H (73%) were shortened in group B. CONCLUSION: EOG was abnormal in 57% in group A. ERG abnormalities could only be found in 50% of group A, mainly in the inner retina. Since also the total dose of vigabatrin and the amount of visual field loss did not really show a correlation with the electrophysiological findings and results of literature are not unanimous, electrophysiology does not appear at present to be a good method to detect patients with, or at risk of, vigabatrin associated visual field loss. Regularly performed visual field examination remains the cornerstone in screening.

Adult↗

PubMed2001

Visual field loss associated with vigabatrin: quantification and relation to dosage.

PURPOSE: To describe the correlation between visual field loss and the duration, dosage, and total amount of vigabatrin (VGB) medication in a group of patients with epilepsy. Co-medication of antiepileptic drugs (AEDs) and compliance were also studied. METHODS: Ninety-two patients (53 male and 39 female) taking VGB medication in the past or the present, attending the Outpatient Epilepsy Clinic in Utrecht, were examined with the Goldmann perimeter. The amount of visual field loss was calculated by the Esterman grid method and by a new method, with which the percentage surface loss of the visual field is measured. A complete drug history was compiled, specifying the amount and duration of VGB medication. Concomitant AED medication was noted. Serum levels of AEDs were determined. RESULTS: Linear regression showed the total amount of VGB as the most significant parameter to predict visual field loss (p < 0.001). Further, men were more affected than women (p = 0.026). Compliance was good, and other AEDs did not influence the results. CONCLUSIONS: Because prolonged use of VGB medication is correlated with the amount of visual field loss, VGB should be prescribed only when there are no alternatives. In such cases, we recommend an examination of the peripheral visual field before starting therapy and a repeated examination every 6 months.

Adult↗

PubMed2000

Concentric contraction of the visual field in patients with temporal lobe epilepsy and its association with the use of vigabatrin medication.

PURPOSE: To describe concentric visual field loss found in the presurgical evaluation of patients with drug-resistant temporal lobe epilepsy and relate the findings to potential causative factors. METHODS: A series of 157 consecutive patients with drug-resistant temporal lobe epilepsy, who had been selected for neurosurgical treatment, was examined in a study set up as a prospective investigation of their visual fields, to document the loss of visual field resulting from surgery. Pre-as well as postoperative visual field examinations were performed following a standard protocol using static and kinetic perimetry. As a number of patients appeared to have an unexplained concentric visual field contraction in the presurgical examination, a relation with potentially causative factors was analyzed in a cross-sectional study of all these patients. Correlations were sought with duration and severity of the seizure disorder, underlying pathology as indicated by magnetic resonance imaging (MRI) and demonstrated by pathology, any type of antiepileptic drug (AED) ever prescribed, and gender. RESULTS: In this cross-sectional analysis of 157 consecutive patients who were candidates for surgery for temporal lobe epilepsy, absolute concentric contraction of the visual field of 10 to 30 degrees was found in the presurgical examination in 20 (17%) of 118 patients who had ever used vigabatrin (VGB) and in none of 39 who had not had this medication. This difference was significant (p = 0.004). In addition, men [15 (21%) of 72] were significantly more often affected (p = 0.007) than women [five (6%) of 85]. The degree of visual field loss, as indicated by the Esterman grid, showed a positive correlation with the duration of VGB medication. There was no correlation of visual field contraction with a history of meningitis as potential cause of the epilepsy, duration of the epilepsy, status epilepticus in the medical history, or histologic abnormality of the brain tissue removed. Ophthalmologic examination of the patients with concentric contraction revealed no abnormalities. None of the patients with concentric contraction complained spontaneously of their visual field loss. CONCLUSIONS: VGB medication is a causative factor in concentric visual field loss. Visual field examination of patients using VGB should be seriously considered.

Anticonvulsants↗

PubMed2000

Long term changes in the visual fields of patients with temporal lobe epilepsy using vigabatrin.

AIM: To study the long term changes in the concentric contraction of the visual field in patients with temporal lobe epilepsy on vigabatrin medication. METHODS: Repeated Goldmann visual field examinations were compared in 27 patients with drug resistant temporal lobe epilepsy and concentric contraction of the visual field. Two groups were studied: 16 patients who had already stopped vigabatrin medication before surgery and 11 patients who continued vigabatrin medication. RESULTS: Concentric contraction of the visual field did not change in 16 patients who stopped vigabatrin before the first examination; there was slight but significant progress in visual field loss in 11 patients who continued the use of vigabatrin. CONCLUSION: Long term follow up of concentric contraction in this selected group of patients indicates that vigabatrin associated visual field loss is not reversible and that progression is possible when vigabatrin is continued.

Anticonvulsants↗

PubMed1982

The Friedmann Visual Field Analyser Mark II--technical evaluation and clinical results.

The perimetric concept and the technical construction of the Friedmann Visual Field Analyser Mark II (VFA Mk II) were evaluated. This instrument for multiple stimulus static campimetry of the central 25 degrees is the successor of the Friedmann VFA Mk I. The number of stimuli is increased (99 vs. 47) and the console is improved. The positions of the presented stimuli are indicated on a LED-monitor. The mechanical and electrical construction of the VFA Mk II appeared to be good. 106 eyes of patients and normal subjects were tested and we conclude that the larger number of stimuli, though improving the chance of detecting small defects, complicates the manual registration and the interpretation of clinical results and prolongs the test, especially in the case of visual fields with substantial defects.

Glaucoma↗

PubMed1982