Cerebral Arteriovenous Malformations and Spontaneous Hemorrhage
ABSTRACT & COMMENTARY
Source: Mast H, et al. Risk of spontaneous haemorrhage after diagnosis of cerebral arteriovenous malformation. Lancet 1997;350:1065-1068.
Few large studies provide outcome analyses on patients suffering from cerebral arteriovenous malformations (AVM). Mast and associates describe such in 281 unselected consecutive patients who first presented with either hemorrhagic (142) or non-hemorrhagic (139) AVMs. Data selection began in January 1987 and continued to May 1996. The authors base their statistics on patient performance from first contact to the application of either endovascular, surgical, or radiation treatment. Kaplan-Meier tables were formulated for the frequency of AVMs during known follow time.
Within the hemorrhagic group, 13% (n = 18) bled during the first year of study (apparently for the second or more time) before treatment was applied, whereas only 2% (n = 3) of the non- hemorrhagic group suffered a first bleed during that time. Mean follow-up time between admission to study and first application of treatment was 8.5 (range, 0.1-96.4) months among the bleeders vs. 11.9 (range, 0.4-90.9) months among the non-bleeders.
Given the large numbers of treats withdrawn from the statistics, actual numbers of non-treats fell off rapidly by the end of the first year of study, leaving the group of non-bleeders at 37% at six months and 24% at 12 months. In bleeders, non-treats fell to 23% at six months and 14% at 12 months. Why outcomes in treated patients were not reported is not explained.
Extracting evaluated outcomes based on the above calculations, Mast et al place the annualized expected bleeding rates for the original non-hemorrhagic group at 2% and the non-treated hemorrhagics at 17.8%. For unexplained reasons, 33% of untreated bleeders rebled during year one compared to 11.3% per year subsequently. No non-bleeders on entry bled during year one, but their incidence rose to an average of 3% for subsequent years. The large drop-off in numbers of patients who had not received treatment by 6-12 months following first symptoms makes it difficult to extract guides for management and outcome for the initial total patient group. Nevertheless, among the total of 21 patients who hemorrhaged during follow-up, only half suffered permanent neurologic damage, and only two were disabled. Nevertheless, these data reaffirm that prognosis in patients with AVM is far worse among those who bleed as first event compared to those who initially present themselves because of seizures, chronic headache, neurological deficits, or other non-hemorrhagic causes.
COMMENTARY
This is an interesting study, for it begins to quantify what most neurologists sense intuitively. An earlier literature study by this group (Mast H, et al. Stroke 1995; 26:1215-1220) indicates that about 60% of diagnosed patients with AVM suffer hemorrhage. Other large series often fail to include modern therapeutic techniques for these persons, making current best management uncertain. The current study "cancelled" from further analysis any patient who received specific treatment. This is unfortunate from a clinical standpoint, since without knowing the eventual outcome of the "treated" group it becomes impossible to know whether specific therapy alters the post-treatment course. Even knowing why treatment was withheld for a mean of 8.5 (hemorrhage group) to 11.9 (non-hemorrhage) months leaves one uncertain as to what factors led to the delay. fp
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