'THE NOSE is quite a big place, really,' said Miss Valerie Lund, a surgeon at the Royal National Throat, Nose and Ear Hospital in London. Using a forefinger and thumb, she carefully withdrew the narrow metal tube that was hidden in the patient's left nostril and held it up to show just how big this particular nose was. It was about two-thirds the length of a ballpoint pen but had fitted quite comfortably.

The patient, Gillian Anderson, was under general anaesthetic and the metal tube inserted into her nose was an endoscope - an optical tube with a light at one end and a camera at the other. Mrs Anderson was being treated for blocked sinuses with the aid of a new technique known as endoscopic sinus surgery.

Endoscopic surgery allows surgeons to examine and operate on parts of the nose that were hitherto impossible to see, let alone reach. With the aid of a magnified image provided by the endoscope, and without making any incision, the surgeon can remove tissue blocking the narrow passages at the top of the nose, allowing the sinuses to drain more freely.

Endoscopes have become commonplace in surgery on organs such as the gall bladder, kidneys and female reproductive organs, but they are now also being used more widely in operations on the nose and sinuses.

As Miss Lund fed the endoscope into her patient's nose, towards the frontal sinuses that occupy the part of the skull at the top of the nose and between the eyes, the powerful light could be seen shining through the bone, illuminating the skin around Mrs Anderson's eye from within.

The television screen by the operating table, connected by cable to the endoscope, showed landscapes that would not have looked amiss in a science-fiction movie. What looked like three enormous pink and glistening barrage balloons were hanging down in the airway. Magnified many times, these were the turbinates - appendages in the nose that warm and humidify the air as it is breathed in. Enormous hairs, curved and vicious-looking, poked up into the endoscope's path.

Miss Lund began work with a variety of delicate instruments. On the screen, what looked like a huge pair of shears grasped and severed an enormous lump of swollen tissue. 'Specimen jar,' barked the assistant surgeon. The 'shears' were then removed from the patient's nose to reveal a pair of dainty fairy scissors with blades just millimetres long, holding a morsel of flesh. A miniature nozzle, attached to a suction pump, vacuumed up blood as Miss Lund completed the task of widening the drainage passages. The endoscope was inserted into Mrs Anderson's other nostril and the process repeated. The operation took about half an hour.

Sinuses are air-filled cavities in the bones of the skull; no one knows what their purpose is. One theory is that they make the head lighter than if it were solid bone and help to make the voice more resonant. Another possibility is that they act as a buffer, or 'crumple zone', if the face is knocked.

There are four major sets of sinuses, all of which drain into the nose. The maxillary sinuses lie within the cheekbones. Above the eyes, in the bones of the forehead, are the frontal sinuses. In the bones between the eye sockets and the nasal cavity is the honeycomb of bone known as the ethmoid sinuses. Behind them, in the middle of the head and forming part of the roof of the nasal cavity are the two larger sphenoid sinuses.

All the sinuses are lined with a thin membrane of cells, which produce mucus to trap particles of pollen and dust. Numerous hairs, called villi, on the surface of the cells carry the mucus and the entrapped particles from the sinuses into the nose and from there towards the throat.

All or any of the sinuses can become infected, causing the membrane to become thickened and swollen; as a result, the narrow drainage passages into the nose become blocked and fill with infected material.

Estimates suggest that up to 8 per cent of the population suffers from sinusitis at some time. In chronic cases, there is a persistent discharge of infected mucus running either into the throat - the so-called 'post-nasal drip' - or into the front of the nose. The nose feels blocked and the sufferer may have facial pain and feel unwell. In acute sinusitis, the infection causes pain across the brow or cheeks and a high temperature. Most such infections can be treated with antibiotics, but they often recur.

In Mrs Anderson's case, blocked sinuses caused severe headaches and infections in her nose. 'I was continually blocked up. People were always asking if I had a cold when I did not have one,' she says.

An operation to make a hole inside her nose helped the sinuses to drain properly for a few years, but then the headaches started again. 'I woke up each day with a headache. I had a headache all day, and nothing I took would shift it,' she says. Investigations showed that her sinuses had become blocked again. This time, she was referred to Miss Lund.

Endoscopes allow surgeons to tackle the root cause of sinusitis: blockages in the narrow drainage passages, known as clefts, at the top and front of the nose, Miss Lund says. An infection in one of these clefts can form a bottleneck throughout the whole system. Removing small pieces of tissue from this area, either by cutting or suction, allows the sinuses to drain more freely.

'This area is quite difficult to get at,' she says. 'Without the endoscope, it involves making a cut on the face. The new surgery means the patient doesn't have a scar and is out of hospital more quickly.'

The endoscope is just 4mm in diameter and incorporates a light source and a camera, making examination and diagnosis much easier. A CT scanner may also be used to provide doctors with a precise image of the bones of the skull. Miss Lund says: 'The anatomy of the sinuses is unique to each individual, and the scan gives us a road map to work to.'

She emphasises that many surgeons, including herself, still do conventional surgery, using normal vision, to drain the affected sinuses, with good results. This can involve making a hole in the nose, or incisions in the mouth or near the eye.

However she says that conventional surgery is not only more invasive, but also means only one or perhaps two sets of sinuses can be drained at a time, so a patient could be left suffering from other blockages. The new operation, which drains the clefts, allows all sinus problems to be dealt with simultaneously.

Ten years ago, Miss Lund estimates, only about 12 ear, nose and throat surgeons in the UK were using the new technique. But in a recent survey covering 375 surgeons, 138 said they were now doing endoscopic sinus surgery. Some surgeons may not have taken it up because of the need for a CT scanner and the expense: endoscopes cost about pounds 1,600 each.

As with any new technique, surgeons also need to be trained. Miss Lund says: 'The endoscope does not make the surgery either safer or more dangerous. But as with any sinus surgery, you are operating close to the eye and the base of the skull, so there is the potential for complications.'

Surveys of her own patients have shown a high degree of satisfaction with the new operation. Just 24 hours after her operation, Mrs Anderson is already pleased with the result. Sitting on the edge of her bed, she says: 'When they took the pack out of my nose this morning, it was brilliant. I can breathe more clearly already.'

(Photograph omitted)