Cavernous sinus thrombosis

This is one of those conditions almost nobody has heard of until they meet it, and one worth knowing about in advance, because the clock runs in hours. An ordinary infected spot on the face, or a sinus infection that drags on, ends in the rarest of cases with the infection reaching a venous cavity that sits directly behind the eye, where the blood then clots. From there the eye, the nerves and the brain are all at risk. The condition is rare but lethal, and it is recognised not by a blood test but by a combination of signs visible to the naked eye. That combination is what follows.

What happens behind the eye

The cavernous sinuses are a pair of venous cavities beneath the base of the brain, immediately behind the eye sockets. Blood leaves the head through them, and running through them are the nerves that move the eye and branches of the nerve supplying sensation to the forehead, eyelid and cheek. Drainage continues along a chain of sinuses and ends up in the internal jugular vein.

The peculiarity of this area is that the veins of the face have no valves, so blood can travel through them in either direction. An infection of the skin of the nose or lip, or of a sinus, can therefore climb against the usual flow and arrive directly in the cavernous sinus. The body responds by clotting: the thrombus is an attempt to seal the bacteria in place. The idea is sound and the consequences severe, because drainage from the eye is blocked, pressure rises, the eye is pushed forward, the nerves are squeezed and stop working, and the clot usually fails to hold the infection anyway.

What it looks like from day one

It almost always begins with headache: sharp, sitting behind or around one eye, building day by day, and not relieved by ordinary painkillers. A few days before, there is often a boil on the face, a sinus infection or a bad tooth.

Then the eye signs arrive, and it is these that make the picture recognisable:

• the eyelid swells, the eye is pushed forward, and around it there is redness and tightness;
• it all starts on one side and within a day or two crosses to the other eye; this detail is very characteristic, because the two sinuses connect with each other;
• vision doubles and the eye turns poorly to the side, with outward movement lost first;
• the upper lid droops and the pupils become unequal;
• the eye itself hurts, sometimes severely, and vision clouds over;
• the skin of the forehead and upper lid on the same side goes numb or burns.

Added to this are a high temperature, chills, nausea and vomiting, and if things are left, seizures, deepening confusion and drowsiness that can end in coma. A similar picture is produced by orbital cellulitis, which is far commoner; telling them apart is only possible in hospital, and both need equally urgent action.

When to call the emergency number

Do not wait until morning and do not drive yourself if any of the following appears:

• severe headache behind or around the eye that painkillers do not touch or that grows worse day by day;
• headache that intensifies on lying down or bending forward;
• swelling, redness or forward bulging of an eye, particularly if the other one starts to swell the following day;
• double vision, a drooping lid, restricted eye movement, loss of vision;
• any of the above together with fever, a recent boil on the face, a sinus infection or an infected tooth;
• seizures, confusion, unusual drowsiness, vomiting;
• a rash of tiny pinpoint bleeds under the skin that does not fade when pressed with a glass.

Even if the alarm turns out to be false, these signs need to be looked at the same day: the list of things behind them is short and every item on it is dangerous.

Where the infection comes from

In most cases the culprits are staphylococci arriving from the face or the sinuses. The usual sources are infection of the sinuses behind the cheekbones and forehead, a boil on the nose, on the upper lip or inside the nostril, an abscess at the root of a tooth and, less often, an infection of the ear or of the eye socket.

From this comes a simple and very practical rule: spots in the area from the bridge of the nose to the corners of the mouth must not be squeezed. That zone is called the danger triangle of the face for good reason, because its veins lead straight to the cavernous sinus and finger pressure drives bacteria inwards. A growing, painful boil there, especially with a fever, is treated with antibiotics rather than in front of the bathroom mirror.

Less often the clot forms with no infection at all. Behind it then lie serious head injury, pregnancy and the weeks after birth, an inherited tendency to clotting, autoimmune diseases with inflamed vessels, some tumours, dehydration, and hormonal contraception, whose contribution is small but real and adds to the other factors.

A rare cause worth knowing about

Fungal infection, mucormycosis, stands apart. It occurs almost exclusively in people with poorly controlled diabetes, particularly after an episode of very high blood sugar with ketoacidosis, and in those receiving chemotherapy, prolonged high-dose steroids or a transplant. The fungus grows from the nose and sinuses into the eye socket and on into the skull, destroying tissue as it goes.

What raises suspicion is what does not happen in ordinary sinusitis: a black or greyish crust on the nasal septum, on the palate or on the skin around the nose, numbness of half the face, pain clearly out of proportion to what can be seen, and rapidly failing vision. All of it develops within days. Treatment here is different, with antifungal drugs and urgent surgery to remove the affected tissue, and speed determines literally everything. If you have diabetes and these signs appear while your blood sugar is high, say so the moment you arrive at the emergency department.

What hospital does, and how it ends

The diagnosis is confirmed with contrast imaging, either a CT or an MRI scan, backed up by blood tests and cultures; if meningitis is suspected, a lumbar puncture is done. Treatment is always in hospital, usually in intensive care.

• Antibiotics intravenously, at high doses and aimed at the most likely bacteria. They are started immediately, without waiting for cultures, and continued for several weeks;
• clearing the source. Pus in a sinus, in the eye socket or around a tooth has to come out, either with a needle or in theatre. While the source remains, antibiotics work at half strength;
• anticoagulants. Heparin is used to stop the clot growing; the decision is made case by case, weighing the risk of bleeding;
• corticosteroids in some patients, to reduce swelling and pressure on the nerves;
• supportive care: pain relief, fluids, blood sugar control and anticonvulsants if seizures occur.

The outlook is serious. Before antibiotics the condition was almost always fatal; far fewer people die now, but published mortality remains high, and some survivors are left with lasting damage: reduced vision in the affected eye, persistent double vision, seizures, headaches. Complete blindness is uncommon. The hospital stay usually runs into weeks and recovery into months, and the single thing that most influences the outcome is how early treatment began.

Online consultation

This thrombosis itself is not treated remotely: with the picture described above, an ambulance is what is needed. Everything that comes before it, though, suits an online appointment well. A doctor can go over a sinus infection that has not settled in a fortnight, look at a boil on the nose or lip and say whether antibiotics are required and why it must not be touched, review a toothache with a swollen cheek, and help decide whether to wait or be seen today. Diabetes control is a subject of its own here, because it is precisely what determines whether you fall into the risk group for the fungal complication. And if there is already a bulging eye, double vision, restricted eye movement or severe pain behind the eye, do not spend time typing: call the emergency number.

This material is for information only and does not replace medical advice.