66 THE NOSE AND PARANASAL SINUSES loses its resonance. There is catarrh, at first mucoid, and becoming muco- purulent until the ostium closes when the discharge may cease, to reappear when the ostium reopens. Postnasal catarrh and a feeling of fullness in the nasopharynx may be experienced. The affected sinus is tender on pressure, often acutely so. Maxillary sinusitis causes infra-orbital pain. Ethmoidal sinusitis gives rise to pain over the bridge of the nose and between the eyes, while in sphenoidal sinusitis the pain may be occipital, vertical or retro-ocular. The pain of acute frontal sinusitis is supra-orbital with a characteristic periodicity. It starts in the forenoon, reaches its peak about midday and subsides in the afternoon, and thus does not disturb sleep at nights. During the exacerbation the sinus is exquisitely tender, the conjunctivae are injected and photophobia may be complained of. Acute maxillary sinusitis is the most frequent form of acute sinusitis, then acute frontal sinusitis, while acute ethmoidal and acute sphenoidal sinusitis are seldom found as separate clinical entities. Acute ethmoidal sinusitis occasionally presents in young children in whom it may not be recognized until the infection passes through the lamina papyracea to give rise to an orbital cellulitis which shows itself as an inflammatory oedema of the eyelids, especially the upper eyelid, beginnuig at the inner canthus and spreading laterally to involve the whole lids (see Fig. 23, p. 54). CLINICAL FEATURES. Anterior rhinoscopy shows congested oedematous mucosa and the inferior concha may be so swollen as to prevent a view of the middle concha and meatus. If it is not turgid, or if it has been shrunk by the application of cocaine hydrochloride solution on a pledget of cotton-wool, the middle concha may be inspected. Its mucosa is similarly congested and oedematous, and if the ostium is patent a streak of mucopus will be seen in the middle meatus (Plate III, 2). This starts high up and anteriorly in frontal sinus infection, but lower down and further posteriorly in maxillary sinusitis. The presence of mucopus confined to the olfactory cleft (Plate III, 3) medial to the middle concha suggests that the posterior ethmoid cells or the sphenoid sinus may be involved. Posterior rhinoscopy will show mucopus in the choana on the affected side (Plate III, 4). There may be flushing and some swelling of the affected cheek in maxillary sinusitis, while oedema of the eyelids or of the forehead will suggest infection in the frontal or anterior ethmoidal sinuses. Tenderness^ over the inflamed sinus will be elicited on pressure, and palpation must be gentle and must avoid the supra-orbital and infra-orbital nerves which may be tender in trigeminal neuralgia. Radiography of the sinuses must be performed. The standard occipito- mental and lateral views are usually sufficient but oblique and verticomental projections may be required to display the ethmoid and sphenoid sinuses (see Fig, 30, p. 71). The acutely inflamed sinus will appear homogeneously opaque (Fig. 28) or a fluid level may be present (Fig. 29). DIFFERENTIAL DIAGNOSIS. This usually presents little difficulty when there is a history of a preceding coryza, -pyrexia and sinus tenderness, but acute sinusitis may have to be distinguished from other causes of headache and from such dental lesions as apical abscess and an impacted tooth. TREATMENT. Treatment is directed to controlling the infection and to establishing drainage from the sinus by reducing the mucosal swelling which occludes the ostium.