The ethmoid is a small bone in the skull, located behind the bone in the nose, between the two eye sockets. It notably forms the upper part of the nasal cavities and part of the sinuses.

This bone, with a complex geometry, participates in the architecture of several structures of the face:

• the orbital cavities, of which it constitutes a part of the internal wall;
• the nasal cavity, of which it forms the ceiling and part of the walls, as well as the back of the nasal septum (also called the nasal septum). This vertical bony lamina, which separates the two pits, in fact belongs to the ethmoid;
• the ethmoid sinuses, hollowed out on each side of the ethmoid.

The ethmoid is also crossed by the endings of the olfactory nerves, as evidenced by the tiny and numerous holes with which its upper surface is riddled. It is on it, in fact, that the olfactory bulbs rest.

Apart from its architectural role, the ethmoid has an amplifying role in the reception of olfactory signals. Two projections of this bone in the nasal cavities, in the form of shells, constitute the nasal turbinates responsible for directing the breathed air towards the olfactory cells.

On either side of the ethmoid are also the sinuses, called ethmoid sinuses, made up of cavities filled with air. Their walls are lined with a mucous membrane comparable to that of the nasal cavity, but their exact role is not yet fully understood. We are especially aware of their existence when they become infected or become blocked.

Ethmoiditis

Ethmoid sinusitis, or ethmoiditis, is the inflammation of the lining that covers the ethmoid sinuses, following a bacterial infection. It may affect a single ethmoid sinus or both, or even be associated with involvement of other sinuses. In its most acute form, which affects children more often than adults, it is manifested by the following symptoms:

• swelling of the upper eyelid, at the level of the inner corner of the eye, which gradually extends;
• violent pain at the level of this edema;
• bulging eye (exophtalmie);
• accumulation of pus in the eye, and purulent discharge from the nostrils;
• high fever.

At the slightest evocative sign, an emergency medical consultation is recommended. 

Rapid treatment is indeed necessary to avoid the complications of this pathology:

• oculomotor nerve palsy;
• loss of sensitivity of the cornea;
• meningeal syndrome (severe headache, stiff neck and vomiting).

There are also chronic forms of ethmoiditis, less violent but lasting beyond three months. Among the most frequent causes: malformation of the turbinates or the nasal septum, or a favorable genetic background. 

Ethmoid adenocarcinoma

This malignant tumor, which develops in the mucous membrane of the ethmoid sinuses, is rare (around 200 new cases per year in France). Linked to the regular inhalation of wood, leather or nickel dust, it is generally of occupational origin. It is also recognized as such by the Health Insurance (subject to an exposure period of five years).

This sinus cancer has a fairly slow progression, with a lag phase of several years. Symptoms can therefore appear after stopping the activity in question, in various forms. It could be : 

• unilateral nasal obstruction that does not pass, often accompanied by a mucopurulent discharge (rhinorrhea), possibly streaked with blood;
• epistaxis, or repeated, unilateral and spontaneous nosebleeds, occurring without an obvious local or systemic cause;
• loss of smell or part of hearing, possibly associated with swallowing disorders;
• painful edema of the upper eyelid, potentially associated with infection of the lacrimal sac (dacryocystitis). Because of this swelling occurring in the constrained space of the orbit, the eye may bulge out (exophthalmos) and the eyelid droop (ptosis). We can also observe ocular paralysis or diplopia (simultaneous perception of two images of the same object).

In case of ethmoiditis

In its acute form, this sinusitis is a medical emergency. Antibiotic treatment should be prescribed without delay to fight the infection, then a clinical check-up carried out 48 hours after the start of treatment makes it possible to verify its effect.

If complications have already appeared, prolonged, broad-spectrum intravenous antibiotic therapy is necessary. It can be set up in the hospital or on an outpatient basis, and be accompanied by corticosteroid therapy to relieve pain.

Surgical drainage can also be done to remove the abscess that has formed. This ethmoidectomy, performed by an ENT or maxillofacial surgeon, is performed through the nasal cavity. It consists of opening the ethmoid bone to access the sinuses and perform their cleaning.

In case of adenocarcinoma

If it is not too extensive and if the general condition of the patient allows it, the treatment consists of an endoscopic ethmoidectomy: the surgeon passes his instruments, including a small camera, through the nose to remove the piece of bone. and diseased mucosa. The operation is usually followed by radiotherapy. Reconstruction may be necessary to close the base of the skull.

When surgery is not an option, treatment combining chemotherapy and radiotherapy is offered.

The diagnosis of ethmoiditis is initially based on a clinical examination. Several additional examinations can then be performed at the request of the health professional consulted: CT or MRI, bacteriological samples. They make it possible to confirm the diagnosis, to identify the pathogenic strain in question and / or to look for complications. 

Sinus cancer is often silent before manifesting itself, systematic screening, by ENT follow-up and nasofibroscopie, is offered every two years to exposed employees and former employees. The diagnosis is made on a biopsy, performed, in case of doubt, during fibroscopy.