Laboratory and Radiologic Studies

The reconstructive surgeon should review the laboratory and radiologic exams ordered by the extirpative surgeon during the preoperative and metastatic workup of the head and neck patient. Abnormal liver function, platelet count, blood urea nitrogen, prothrombin, and/or prothromboplastin time may lead to significant intraoperative blood loss and post-operative hematomas and possible compressive flap loss and/or infection. These abnormalities need to be investigated and corrected as much as possible preoperatively. Preoperative albumin, prealbumin, and leukocyte count can give an estimate of the level of malnourishment that can affect post-operative healing. Usually computed tomography (CT) and magnetic resonance imaging (MRI) scans of the head and neck region are the dominant radiographic studies ordered. These studies complement and confirm the history, physical exam, and endoscopic evaluation, and help to further delineate the tumor extent locally, regionally, and distantly. This is a key step for both extirpative and reconstructive reasons, as the educated estimate of the anticipated surgical defect dictates the further necessary preoperative workup for the reconstructive surgeon. CT, MRI, bone scan, and panorex findings can also to varying degrees help to indicate mandibular involvement and the need for segmental resection and subsequent bony reconstruction (18,19). MRI followed by MRA, CT angiography, Doppler, and/or angiography is used in cases of potential resection for carotid artery involvement. These data can also indicate the adequacy of the external carotid branches to support microvascular anastamosis (20). At times, the patency of the transverse cervical arterial system and viability of the dependent trapezius flap network can also be determined. The integrity of potential microvascular recipient veins in the neck can also be detected radiographically, including predicting the need for sacrifice of the internal and/or external jugular venous network. The need for venous angiography would be rare.

Radiographic evaluation of the determined potential regional and distant reconstructive flap donor sites should help supplement the physical exam in determining safe harvest. A preoperative Allen's test is crucial for maintaining adequate hand perfusion after radial or ulnar forearm free-flap harvest. In cases with an equivocal subjective Allen's test, Doppler plethysmography can objectively document adequate collateral perfusion to the donor hand (15). Since most head and neck cancer patients also are at risk for significant and progressive peripheral vascular disease due to smoking, other clinical, Doppler, MRA, and angiographic techniques have been used adjunctively to study vasculature prior to harvest of extremity free flaps (21-24). These studies can detect anatomic abnormalities, assure adequate cutaneous flap perforator supply, and document the adequacy of distal collateral arterial flow. In patients with previous trauma or surgery, plain X-ray films can document adequate boney integrity and any compromising hardware.

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