Cavernous sinus thrombosis: a late complication of head and neck surgery

Abstract

Cavernous sinus thrombosis is a rare but fatal condition arising due to various infectious and noninfectious causes. Although its incidence is very low in the setting of head and neck surgery, including radical neck dissection, a high index of suspicion with prompt treatment is the key to a successful outcome. We report a case of a 50-year-old woman with a chondrosarcoma of left lower alveolobuccal complex who underwent en bloc tumour resection with infratemporal fossa clearance and left modified radical neck dissection. Subsequently, she developed cavernous sinus thrombosis, which was successfully managed with a multidisciplinary approach. This case highlights the importance of high clinical suspicion in the postoperative setting to diagnose this potentially lethal complication.

Background

Cavernous sinus thrombosis (CST) is a rare but life-threatening condition caused by both septic and aseptic aetiologies. The septic causes include infections in the dangerous areas of the face (between the angles of the mouth and the bridge of the nose), sinusitis, orbital cellulitis and traumatic injuries in a patient with a clinical or subclinical thrombophilic disorder, whereas the aseptic causes are surgery, malignancy, trauma, pregnancy and chemotherapy.¹

The incidence of cerebral venous thrombosis due to radical neck dissection is quite low. In the setting of neck dissection, it occurs as a result of the retrograde propagation of thrombus originating in the internal jugular vein (IJV).² We report a case of a 50-year-old woman with a chondrosarcoma of left lower alveolobuccal complex who underwent en bloc tumour resection with infratemporal fossa clearance and left modified radical neck dissection. Subsequently, the patient developed signs of third cranial nerve palsy and decreased vision that was diagnosed to be due to CST. The patient was managed conservatively with antibiotics and anticoagulants with a favourable outcome.

Case presentation

A 50-year-old woman with no comorbidities presented to us with a rapidly progressive growth over the left lower alveolus since 4 months. The intraoral examination showed 10 cm × 8 cm fungating growth in the left lower alveolus involving the entire floor of the mouth and extended from the level of the first premolar anteriorly to retromolar trigone posteriorly. There were multiple enlarged lymph nodes in the neck at levels IB, II and III. The histopathological examination of the punch biopsy of the lesion demonstrated features of a chondro-osseous lesion. Contrast-enhanced CT scan of the face and neck revealed lytic destruction of the left hemimandible with a large soft tissue component extending into the floor of the mouth along with multiple enlarged lymph nodes in the left lateral neck. The patient was planned for surgery of both the primary tumour and the neck along with reconstruction.

Intraoperatively, we found a fungating tumour in the left lower alveolus involving the entire mucosa of the floor of the mouth. The tumour was infiltrating the infratemporal fossa including the medial pterygoid and lateral pterygoid muscles and the insertion of the temporalis muscle. The patient underwent left composite resection, that is, en bloc removal of the tumour with left classical hemimandibulectomy along with infratemporal fossa clearance. Left modified radical neck dissection—type II was also done, thereby preserving the spinal accessory nerve and IJV. The defect was reconstructed using a pectoralis major myocutaneous flap for the inner lining, while the outer lining was primarily closed using the skin. The patient was discharged in a stable condition on the 10th postoperative day on nasogastric tube feeding. The final histopathology of the tumour was diagnostic of myoepithelial carcinoma involving the underlying bone with a MIB-1 proliferation index of 80%. All the resected margins were free of tumour. All the 17 lymph nodes dissected were also free of tumour.

The patient again reported to us on the 25th postoperative day with the drooping of the left upper eyelid, decreased vision from the left eye, headache and vomiting (figure 1). An urgent contrast-enhanced CT of the head, face and neck was done, which found an expanded left cavernous sinus with a convex lateral margin with few ill-defined hypodense foci within. The diameter of the left superior ophthalmic vein was normal. The left suprahyoid IJV was also found to be thrombosed (figure 2A). Overall, radiological features were diagnostic of left CST. The routine blood parameters including complete blood counts were within normal limits, suggesting an aseptic aetiology.

Figure 1.

Ptosis of the left eyelid (A) and conjunctival chemosis (B).

Figure 2.

CT scan showing thrombosed left cavernous sinus with convex lateral margin (A) and CT image after anticoagulant therapy showing resolution of thrombosis (B).

The neurology, neurosurgery and neuro-ophthalmology consultations were sought. The neurology and ophthalmoscopic examination showed ptosis of the left eye, a dilated left pupil nonreactive to light with complete ophthalmoplegia of the left eye. The patient was started on an anticoagulant (enoxaparin), broad-spectrum antibiotics, mannitol and steroids. CT brain was done after 4 days of treatment, which revealed a normal optic nerve and a thrombosed cavernous sinus (figure 2B). There were no other abnormal findings. Gradually, the patient started improving with the above medications and was discharged in a stable condition. Subsequent follow-up of the patient in the neurology department continued for a few months where she was managed conservatively and improved. The rarity of this case was discussed with the patient and her relatives and written consent was taken regarding the reporting of this case and the patient’s photographs.

Investigations

Already mentioned in the case presentation

Treatment

Already mentioned in the case presentation.

Outcome and follow-up

Gradually, the patient started improving with the above medications and was discharged in a stable condition. Subsequent follow-up of the patient in the neurology department was continued for a few months where she was managed conservatively and improved.

Discussion

CST is a rare but potentially fatal condition characterised by headache, vomiting, limited movements of the eyeball and, sometimes, complete ophthalmoplegia.^{2 3} The septic causes include infections of the head and neck, including sphenoidal and ethmoidal sinusitis, dental infections, pharyngitis and cellulitis.⁴ Non-infectious conditions like malignancy, pregnancy, chemotherapy and surgery may also lead to CST. CST constitutes 1%–4% of cerebral venous and sinus thrombosis. The incidence of isolated CST is difficult to ascertain owing to the paucity of the literature, although some studies reported an annual incidence of CST of 0.2–1.6 per 100 000 per year.¹

There is a scarcity of the literature on CST occurring in the setting of neck dissection and infratemporal fossa clearance. There are a few reported cases of superior sagittal sinus thrombosis or abducens nerve palsy occurring after neck dissection.^{5 6} The most common symptomatology of intracranial hypertension occurring as a sequel to neck dissection is severe headache, nausea, vomiting and even seizures. These symptoms usually manifest late, even after the patient gets discharged from the hospital.

The diagnosis of CST rests on clinical examination and neuroradiologic findings. The generalised symptoms include nausea, vomiting, severe headache, altered sensorium, lethargy and occasionally seizures. The predominant ophthalmologic signs include ptosis, proptosis, conjunctival chemosis, partial or complete ophthalmoplegia and, rarely, complete blindness. Bilateral blindness is observed in septic CST due to spread through intercavernous venous channels.^{1 7} The contrast-enhanced MRI scan not only diagnoses the condition with accuracy but also evaluates the extent of the thrombosis. The MRI findings of CST are changes in size, signal intensity and configuration of the cavernous sinus, the convexity of the lateral walls of the sinus and, occasionally, the dilatation of the superior ophthalmic vein.⁸

There are no standard guidelines for the management of CST owing to the rarity of the occurrence. The antimicrobial therapy (covering Gram-positive organisms and anaerobes) and antithrombotic therapy form the mainstay of therapy based on expert opinions and are continued for several weeks. Corticosteroids may also be tried to reduce inflammation and vasogenic oedema. Osmotic diuretics like mannitol are useful in cases with signs of increased intracranial pressure.¹ The prognosis of CST was very poor initially with antibiotic therapy alone with some studies reporting mortality as high as 29%–50%. But, now it has remarkably improved in the last few decades after the use of antithrombotic therapy has been added to antibiotic therapy.⁹

In our case, the patient underwent en bloc tumour resection with infratemporal fossa clearance and left modified radical neck dissection. Although IJV was spared during the neck dissection, postoperative MRI showed thrombosis of the suprahyoid IJV. This points to the causal role of infratemporal fossa dissection, which might have led to the formation and propagation of thrombus through the pterygoid plexus of veins into the cavernous sinus that later involved IJV also. Our patient also presented with CST quite late after discharge from the hospital. But prompt diagnosis and management with a multidisciplinary approach led to complete recovery in a few months.

Patient’s perspective.

I am fully satisfied with the treatment given to me by the whole team of doctors. They worked in collaboration and treated me with the utmost care

Learning points.

• Cavernous sinus thrombosis is a rare but life-threatening and sight-threatening complication of head and neck surgery.

• A high index of suspicion is required to diagnose and treat such a rare disorder in the postoperative setting.

• In cases requiring ligation of internal jugular vein (IJV), preoperative imaging may help in ascertaining the dominant venous system before ligating IJV and in preventing this complication.