Head and neck cancer metastases to the cavernous sinus have been rarely reported. Due to more precise imaging diagnostic techniques, the number of reported cases in the last several years has increased.1 The main clinical findings on presentation are related to the involvement of cranial nerves III to VI as they pass through the cavernous sinus. Primary head and neck cancers previously reported as metastasizing to the cavernous sinus include squamous cell carcinoma (SCC) of the larynx, oral cavity, salivary glands and oropharynx; melanoma, nasopharyngeal carcinoma; thyroid papillary adenocarcinoma; rhabdomyosarcoma; adenoid cystic carcinoma; and salivary duct carcinoma.1 Tissue diagnosis and surgical management for lesions in the cavernous sinus present unique challenges given the proximity to the critical cavernous sinus structures, including the internal carotid artery.
Multiple approaches to obtain tissue for diagnosis from the cavernous sinus have been described. These include craniotomy with open biopsy,2 subtemporal approaches for an open biopsy using a computed tomography (CT)-guided surgical navigation system,3 pterional craniotomy with a transsylvian approach,1, 4 transpetrosal approach,1, 5 and image-guided fine needle aspiration of the foramen ovale.1, 6
Expanded endonasal approaches to the middle cranial fossa, and specifically to the cavernous sinus region, have previously been described for sellar and parasellar lesions.7–9 Endonasal endoscopy for cavernous sinus surgery has been studied extensively in cadaver dissection, with reported satisfactory outcomes in patient treatment.10 Frank et al. also reported good results using an endoscopic endonasal approach to pituitary adenomas with intraoperative evidence of cavernous sinus invasion.11 We describe an endoscopic transnasal approach to the cavernous sinus for tissue diagnosis, ultimately guiding treatment and management.
MATERIALS AND METHODS
A review of the medical records of two patients who presented to a tertiary medical center with symptoms of cavernous sinus syndrome was done. Radiographic images, videographic demonstration of the operative technique, and pathology slides are presented.
Both patients presented with ophthalmologic symptoms consistent with cavernous sinus syndrome. The first patient was a 69-year-old female with no prior history of cancer who presented with a 2.5-year history of atypical trigeminal neuralgia. On magnetic resonance imaging (MRI) she was found to have abnormal enhancing tissue within the right cavernous sinus, foramen rotundum, foramen ovale, and the right pterygopalatine fossa (Fig. 1). The second patient was a 69-year-old male with a history of bladder cancer and melanoma, who presented with a right-sided cavernous sinus lesion 7 months after resection, reconstruction, and radiation for an oropharyngeal SCC (Fig. 2).
The described technique was used for both patients (Video 1). (Video 1 included as online supplementary material.) The endoscopic approach for wide opening of the sphenoid sinus and exposure of the cavernous sinus was performed by the otolaryngologist. The lower half of the right middle turbinate was resected using the turbinate scissors, and the microdebrider was used to enter and enlarge the right sphenoid sinus ostium. The posterior septum was removed, and the left sphenoid sinus was opened widely using the microdebrider. The intrasinus septae of the sphenoid were taken down using the pituitary forceps and drill. The superior, lateral, and inferior edges of the sphenoid sinus were drilled down, allowing wide exposure of the cavernous sinus. BrainLAB image guidance (BrainLAB Inc., Westchester, IL) was used to identify the area of interest anterior to the carotid siphon, and a diamond bur was used to drill off the bony lateral wall of the sphenoid sinus over the carotid artery to expose the cavernous sinus. The course of the carotid artery was traced using both ultrasound Doppler and the BrainLAB pointer. The dura was opened anteroinferior to the carotid artery, and biopsies were taken of the tissue of the subdural intracavernous space. The cavernous sinus was further opened to expose the carotid siphon, and deeper biopsies toward the lateral portion of the cavernous sinus were taken. After biopsies were taken of the lesion, free bone grafts were used to reconstruct the bony wall of the cavernous sinus. Fibrin glue was applied, and hemostasis was then achieved with bipolar cautery and Surgifoam (Ethicon, Somerville, NJ). The sphenoid sinus was packed using absorbable sponges.
The tissue diagnosis was metastatic adenoid cystic carcinoma in the first patient and metastatic SCC in the second patient. Figure 3 shows metastatic adenoid cystic carcinoma in the mucosa and evidence of perineural invasion respectively. Postoperatively, both patients recovered well without new vision changes, cranial neuropathies, or bleeding. The first patient went on to receive chemotherapy and radiation for her metastatic adenoid cystic carcinoma. The primary was found in the resected middle turbinate tissue. The second patient underwent stereotactic radiosurgery for his metastatic cavernous sinus SCC. Figure 4 shows the postoperative posterior sinus cavity in the second patient at about 3 months postoperatively, following his radiation therapy. The posterior sphenoid sinus and cavernous sinus walls have completely remucosalized.
Although rare, head and neck cancer metastases to the cavernous sinus have been reported with increasing frequency in the recent literature.1 The majority of cavernous sinus metastases reported have been diagnosed clinically based on characteristic findings on CT or MRI with histopathologic confirmation on autopsy.3 Cavernous sinus lesions present a diagnostic difficulty, as a number of disease entities can simulate metastatic disease. Similar clinical findings are seen in carotid cavernous fistula, pituitary carcinoma, sphenoid mucocele, intracavernous carotid artery aneurysm, carcinomatous meningitis, meningioma, and cavernous sinus thrombosis. Although imaging modalities are useful in narrowing the differential diagnosis, obtaining tissue is paramount in making further treatment decisions. For example, in the case of our second patient, the history of bladder cancer, melanoma, and oropharyngeal cancer complicated the differential diagnosis of his cavernous sinus lesion.
Previously described techniques to the cavernous sinus have primarily been open approaches. As techniques and experience in endonasal endoscopic surgery have increased, an endoscopic approach to the cavernous sinus is now feasible. In both of our patients, the perioperative morbidity was minimal and tissue diagnosis ultimately guided the treatment decisions.
A transnasal endoscopic approach to the cavernous sinus is a safe and efficacious method to obtain tissue specimens of cavernous sinus lesions. A pathologic diagnosis in patients presenting with cavernous sinus syndrome is critical for guiding further treatment and management.