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 mise à jour du
24 février 2002
 Clinical Oncology
cas cliniques
 Sphenoidal sinus mucocoele and yawning
after radiation treatment for nasopharyngeal carcinoma
KYR Wong, KCR Ngan, VC Sin and WH Lau
Queen Elizabeth Hospital, Hong Kong


A 33-year-old Chinese man was diagnosed with nasopharyngeal carcinoma (NPC) in November 1982. The investigations revealed anterior extension of tumour from the nasopharynx to the left posterior nasal cavity. No bony erosion of the skull base was found. There were no neck node metastases. The disease was therefore Stage II (T2NOMO) according to Ho's staging system. Radical radiotherapy was then administered, using a three-field technique (one anterior and two opposing lateral facial fields ). All the fields were equally weighted and eye shields were used for all three. A dose of 66 Gy was given. The neck was not treated prophylactically. The treatment was completed uneventfully in February 1983.

In July 1986, the patient complained of poor memory and suffering from feelings of insecurity, which characterized temporal lobe epilepsy. A CT scan of the brain revealed a small right temporal lobe area of radiation necrosis appearing as a hypodense lesion. Since then, he has required intermittent courses of anticonvulsants to control his temporal lobe epilepsy (the anticonvulsant therapy has occasionally been discontinued according to his wish). He also had postirradiation bilateral sixth cranial nerve palsies.

In September 1995 he developed frequent yawning attacks, which came on almost every 10-15 seconds. They were so disturbing that the patient's speech and attempts at eating were frequently interrupted. A CT scan of the base of the skull showed an expansile mass in the sphenoidal sinus, with erosion of the floor of the sinus and the basiocciput. Subsequent MRI revealed that the sphenoidal sinus was expanded and filled with material of intermediate signal intensity on TI WI images and hyperintense on T2WI, which was suggestive of a mucocoele. The sphenoidal mass was also found to be compressing the pituitary hypothalamic region. Simple surgical drainage and sphenoidal sinus biopsy were, performed, yielding chronic inflamed tissue without any evidence of malignancy. There were no more yawning attacks after the surgical drainage.

In july 1996, the yawning attacks recurred, although they were less frequent. A CT scan of the nasopharynx and the base of the skull showed a recurrence of the sphenoidal mucocoele. Surgical drainage once again successfully stopped the yawning and there was no recurrence in the next 6 months.

DISCUSSION : The late complications following radiotherapy in patients with NPC are well documented. Neurological and endocrinological complications are usually discussed at greater length than others. Radiation-induced sinusitis, caused by scarring and obstruction of the sinuses is often overlooked or neglected, leading to the under-reporting of this complication. Sphenoidal, ethmoidal and maxillary sinuses are all included in the radiation portals. Osteoradionecrosis, and even radiation induced osteosarcoma, of the maxillary sinus have been reported in the literature. Porter have shown a significant increase in mucosal abnormalities in the paranasal sinuses as revealed by serial CT scans before and after radiotherapy in patients with NPC. Indeed, the relatively rare phenomenon of a sphenoidal sinus mucocoele developing after radiotherapy in a patient with NPC has been reported in a Chinese man who presented with blurring of vision in both eyes, which was probably due to compression of the optic chiasma by the mucocoele.

We now report another Chinese patient who developed a sphenoidal mucocoele 13 years after radiotherapy. There was compression of the pituitary hypothalamic region, giving rise to contirmous bouts of yawning. The yawning attacks stopped upon successful drainage of the sphenoidal mucocoele.

The purpose, physiology and neuroanatomical pathways of yawning remain a mystery. The literature, which is mostly based on animal studies, suggests that this involuntary act is controlled through the complex imegration of dopaminergic, cholinergic and catecholaminemediated pathways, with the hypothalamus, brainstem and medulla oblongata as the postulated centres of control. In this patient, compression of the pituitary hypothalamic region caused continuous bouts of yawning. which were disturbing to the patient. Relief of the pressure after surgical drainage of the mucocoele stopped further attacks of yawning.