George L. Bohmfalk

Anaplastic astrocytoma following radiation for a glomus jugulare tumor

Evaluation of radiation therapy for a given neoplasm includes consideration of possible treatment complications as well as potential benefit. A 43‐year‐old male with a glomus jugulare tumor of the right middle ear had received 4480 rads to the right middle and inner ear and temporal bone. Eight years later, he developed an anaplastic astrocytoma of the right cerebellar hemisphere. At this time a third neoplasm, a left carotid body tumor, was demonstrated angiographically. Although radiation can be implicated in the genesis of the glial neoplasm, the presence of two neural crest derived tumors suggests that a lowered threshold for neoplastic transformation in neuroectodermal cells may have been an additional factor. Long‐term follow‐up of large numbers of patients with glomus jugulare tumors will be necessary to determine if multiple paragangliomas predispose to radiation‐associated gliomas.

Aneurysms of the persistent hypoglossal artery.

The primitive hypoglossal artery is one of four embryonic anastomoses between the carotid and basilar arterial systems. The so-called persistent hypoglossal artery is most likely a complex vessel comprised proximally of a persistent hypoglossal artery and distally of components of the primitive lateral basilar-vertebral anastomotic network. This is the sixth reported case of an aneurysm of the persistent hypoglossal artery, and it is unique in its association with two supratentorial aneuryms, one of which had ruptured. All three aneurysms were treated by a direct surgical approach (two operations). Review of the other published cases demonstrates that these aneurysms arise at the junction of the persistent hypoglossal with the basilar artery. Aneurysms of this vessel require direct surgical treatment, because the parent vessel is functionally the only artery supplying the brain stem and therefore may not be ligated. The aneurysms usually lie in the subarachnoid space, indenting the brain stem, and may be approached through a suboccipital craniectomy.

Subclavian steal syndrome

Three patients with central nervous system symptoms due to subclavian steal syndrome were treated with proximal vertebral to common carotid artery transposition. Neurological symptoms were relieved or improved in all three, with no decrease in blood pressure or pulse in the ipsilateral upper extremity. The colorful history of this syndrome is reviewed, and the various surgical approaches to its treatment are discussed. Although the literature suggests that the commonly used carotid to subclavian artery bypass graft and other similar extrathoracic procedures are generally safe and effective for relief of symptoms of the steal, there is also evidence that these bypasses may fail to restore antegrade flow in the vertebral artery, and, in fact, may steal from the carotid artery. Thus, the blood flow provided to the brain by these procedure may be hardly more than that provided by vertebral artery ligation, whereas the principal effect is to restore blood flow into the upper extremity. Vertebral artery ligation alone has been used in 20 patients, with neurological improvement in all cases and production of persistent intermittent brachial claudication in only one. These considerations and our patient experience suggest that a relatively simple operation, proximal vertebral to common carotid artery transposition, which emphasizes restoration of flow to the brain rather than to the upper extremity, may be preferable for most patients with neurological symptoms of subclavian steal syndrome.