{'fraction_non_alphanumeric': 0.022411953041622197, 'fraction_numerical': 0.005869797225186766, 'mean_word_length': 5.648936170212766, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Cranial dural arteriovenous malformation and fistula. Radiological diagnosis and management. Review of thirty four patients.

The clinical features, imaging and angiographic findings of thirty four patients with cranial dural arteriovenous malformations and fistulae are presented in four groups. Group 1--Seven patients with anterior cavernous malformations, predominant superior ophthalmic vein drainage, and symptoms and signs of carotico-cavernous fistula. Group 2--Twelve patients with malformations of the superior petrosal, transverse and sigmoid sinus regions, presenting predominantly with bruit. Group 3--Seven patients with malformations of the basal sinuses and prominent cortical venous drainage, presenting with intracranial haemorrhage, headache and impaired cortical function. Intracranial haemorrhage never occurred in the absence of cortical venous drainage. Group 4--Eight patients with infrequent manifestations. Group 1 and 2 patients are readily recognized and diagnosed. Group 3 and 4 patients are often misdiagnosed. Treatment modalities comprised embolisation therapy, surgical excision, and carotid compression. Twenty patients were treated by one or more of these modalities with a successful outcome in thirteen patients. Group 1 patients are the most amenable to trans-arterial embolisation. Carotid compression as the sole modality of treatment was successful in four patients. Unless the fistula is successfully closed, Group 3 patients and patients who present with cervical or thoracic myelopathy carry a grave prognosis. There is need for greater radiologist awareness of Group 3 and the rarer presentations, particularly myelopathy. With the exception of one patient, the morphological features of our cases are consistent with the now-accepted view that these lesions are acquired arterio-venous fistulae and not congenital malformations.