Management of vascular lesions
Tumour embolization
Embolization has been used in the treatment of a wide variety of head and neck vascular tumours, including congenital haemangiomas. The aim in most cases is to devascularize the tumour prior to surgical excision, although in patients unfit for anaesthetic, embolization may be used as a palliative measure. The commonest use of embolization is in the management of juvenile nasal angiofibroma (JNA), a rare, highly vascular benign tumour found in adolescent males. This lesion commonly originates in the pterygo-palatine fossa, and then expands aggressively through the sphenopalatine foramen into the nasopharynx and nasal cavities followed by the sinuses and orbit, finally extending intracranially. Traditional surgical treatment has comprised an open approach using lateral rhinotomy or mid-facial degloving techniques. More recently, an endoscopic transnasal approach has been successfully described as safe and effective for all but the largest tumours.23 Embolization devascularizes the tumour, minimizing blood loss during surgery and making an endoscopic approach more feasible, and for these reasons is now a well accepted part of the treatment of JNA.24 Figure 3 shows how effective embolization can be in devascularizing JNA. For larger tumours, particularly those showing deep invasion of the sphenoid, there is evidence that a more radical surgical approach is preferable. In these cases, preoperative embolization may make complete tumour excision more difficult, and is not recommended.25 Preoperative imaging with CT and MRI is therefore essential in planning the treatment for each case of JNA.
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Figure 3. (a) DSA of juvenile nasal angiofibroma (JNA) showing microcatheter (black arrow) and tumour blush (white arrow); (b) after embolization there is minimal vascularity of the JNA
Embolization is also used in the treatment of paragangliomas, which are tumours arising from paraganglionic chemoreceptor cells. The commonest examples are glomus tympanicum, glomus jugulare and carotid body tumours. These tumours, which take their blood supply from the ascending pharyngeal artery, may be multicentric, and their ability to spread locally and small malignant potential are well described. Aggressive treatment is therefore recommended, and although surgery remains the mainstay of treatment, preoperative embolization has led to improved resectability and reduced morbidity ( Figure 4).26,27
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Figure 4. (a) Tumour blush of a large glomus tumour before embolization; (b) after embolization of the ascending pharyngeal artery with coils and particles the vascularity is reduced
Arterio-venous fistulas
These abnormal vascular connections can be congenital, spontaneous or traumatic. Treatment of congenital lesions is a challenge, as these have multiple, diffuse anastamoses with the surrounding vasculature.28 Traumatic lesions can also be difficult to treat, in part due to the urgency of treatment required in order to prevent life-threatening haemorrhage, neurological deficit or visual complications. These lesions, such as the carotid to cavernous sinus fistula occurring after head injury, are also often inaccessible surgically. The principle of treatment of arterio-venous fistulas is preservation of the normal vasculature where possible, while ensuring that both the distal and proximal vessels of the fistula are occluded. Various treatment modalities have been described, including embolization with detachable balloons, particles or sclerosants, using both arterial and venous approaches, as well as placement of endovascular stents.28–30 Proper planning of treatment is the key to success, and again requires close cooperation between the interventional radiologist and the head and neck surgeon.
Venous sampling
In recent years, a minimal access approach to parathyroidectomy for the treatment of primary hyperparathyroidism has evolved, making preoperative localization of the abnormal parathyroid gland increasingly important. The usual techniques employed for this include combinations of sestamibi, ultrasound, computerized tomography (CT) and magnetic resonance (MR) scans. When necessary, usually if the above techniques have not convincingly localized the affected gland, or in re-operative cases, a further technique available is that of intra-operative selective venous sampling. In this technique, the veins draining the parathyroid glands can be catheterized and blood sampled for parathyroid hormone. Elevated levels identify the abnormal gland and can be seen to return to normal after surgery. This technique, though invasive, has a high sensitivity and accurately predicts patients who have been successfully cured.31