Isolated infection of the sphenoid sinus is uncommon. It usually occurs in conjunction with other paranasal sinuses. Acute isolated sphenoid sinusitis is observed in fewer than 3% of all cases of sinusitis. It is frequently misdiagnosed because of its vague symptoms and the paucity of clinical findings, but it is a potentially destructive entity.1-3 The diagnosis is often delayed until the patient experiences a neurological complication.
A 66-year-old man with history of hypertension controlled with atenolol 100 mg/die, without other significant diseases, and a 4-week history of severe headache was admitted to a hospital. The headache was persistent, rising from right occipital with irradiation to the neck, at the vertex, right temporal, and frontal regions. The headache was particularly intense during the nighttime hours and not be controlled by paracetamol 1500 mg orally. For 3 days, he had high temperature (39-40°C) and also showed dysuria and pollakiuria and was self-administrating ciprofloxacin 1000 mg orally.
On admission to our hospital, the patient was conscious, cooperative, and well orientated. His vital signs were as follows: temperature, 38.4°C; pulse, 90 beats/min; and blood pressure, 110/60 mm Hg. A physical examination revealed no signs of meningism or neurological deficits. Headache was intolerable, especially when finger pressure was applied to the tendon insertion of the trapezium muscle at the point where the great occipital nerve comes out (second cervical nerve). He did not show nausea, vomiting, nasal symptoms, nasal discharge, postnasal drip, or nasal congestion.
Chest, skull, and cervical x-ray and abdominal ultrasound scan were normal. Laboratory findings showed increased white blood cell count of 17.170/mm3 and C-reactive protein of 7.87 mg/dL.
Ceftriaxone 2 g intravenously and ketoprofen 100 mg intramuscularly twice a day were started. For the first 48 hours, he still had high temperature (39-39.5°C) and a strong occipital headache irradiated to the vertex.
An echocardiogram showed a slight left ventricular hypertrophy (1.3 cm) and excluded endocarditis and pericarditis.
On the third day, the high temperature was the same (39.5-40°C) causing the patient to shiver, and he was confused and disorientated about space and time. Furthermore, he complained of diplopia and a right eye blurring vision. No signs of meningism were present, and bone-tendineous reflexes, tactile, thermic, and crude pressure sensations were normal.
Brain and cervical computed tomographic (CT) scans were normal, and in particular, no relevant modification of the axis was observed. A partial opacification of the right sphenoid sinus was noted. Otoscopy and rhinological examination did not show any abnormality.
The blood cultures were positive for Streptococcus constellatus confirming the diagnosis of septicemia. Therapy with levofloxacin 500 mg plus amoxiclav 6.6 g and amikacin 1000 mg intravenously was started.
A maxillofacial CT scan confirmed an isolated opacification of right sphenoid sinus (Fig. 1).
During the following 48 hours, temperature returned to normal and headache decreased, disappearing in 6 days.
Fifteen days later, the patient underwent a right sphenoidotomy that revealed a mycetoma that was removed. A histological examination showed chronic sinusitis with edema, chorion sclerosis, and muciparous hyperplasia of epithelium and of seromucous glands. Important structural signs of bony remodeling were clear, without bony invasion of the sinus cavity; hypha aggregates and fungi spores were also found (Fig. 2). The fungal elements were morphologically identified as Aspergillus. Bacterial (aerobic and anaerobic) cultures obtained from the sphenoid sinus during sphenoidotomy were negative.
On a subsequent visit, the patient reported to be asymptomatic, and a repeated CT scan showed clear sphenoid sinus.
The sphenoid has been described as the most neglected sinus by Van Alya.4 It is lined with ciliated pseudostratified epithelium with fewer mucous-secreting cells as compared with the other paranasal sinuses. This contributed to fewer drainage problems and may explain the low incidence of isolated sphenoiditis.1,2,5-11
The sphenoid sinus cannot be directly examined by clinical examination due to its difficult-to-reach anatomic position. Therefore, the first step is to have a strong suspicion of isolated sphenoid sinusitis during evaluation of the symptoms and signs.12 Headache is the most significant symptom,1,5,6,13-16 and it has been described in descending order of frequency, as deep-seated retro-orbital, frontal, over the vertex, temporal, occipital, or postauricular.6,7 It is more often nonspecific and may be present anywhere in the craniofacial region.7 The pain usually increases steadily with time, it is refractory to medical treatment and interferes with sleep.2,7 The main symptom of sinusitis is a throbbing pain and pressure around the eyeball, which is made worse by bending forward. Although the sphenoid sinuses are less frequently affected, infection in this area can cause earache, neck pain, or an ache behind the eyes, at the top of the head, or in the temples. In addition, drainage of mucus from the sphenoid down the back of the throat (postnasal drip) can cause a sore throat and can irritate the membranes lining the larynx.
The second important sign is a light persistent fever.
Isolated sphenoid sinusitis is a rare disease with potentially devastating complications such as cranial nerve involvement, brain abscess, and meningitis. It occurs at an incidence of approximately 2.7% of all sinus infections.17 Disease of the sphenoid sinus is often vague and nonspecific in its clinical presentation,8 as in the present case, where a persistent generally occipital headache was present for a month, whereas high temperature and septicemia emerged later.
Isolated sphenoid sinusitis presented with unilateral VI nerve palsy,10 isolated fungal granuloma presented with III nerve palsy,18 acute pansinusitis with bacteraemia19 and septicemia, meningitis, and skull base osteomyelitis9 are reported. Cases of unilateral sphenoid sinusitis presented as septicemia in an otherwise healthy young immunocompetent adult are also reported.
The intracranial complication of acute isolated sphenoid sinusitis is an extremely rare condition.
In 78% of the cadavers, a bony wall between the optic nerve and sphenoid sinus was found to be thinner than 0.5 mm, and also in 8% of cadavers, there was no bony structure between the sphenoid sinus and internal carotid artery.20 Anatomic relation of the sphenoid sinus with the vital structures and the variability of thickness of the bony wall might result in an intracranial spread of the infection, which might cause serious problems.21
Facial pain is thought to be due to the involvement of V1 and V2 nerves.
Visual changes such as blurring or loss of vision constitute the second most common symptom complex. The optic nerve is most commonly involved followed by the sixth cranial nerve.7 Blindness is rare, unless an orbital abscess or cavernous sinus thrombosis develops.12,22
The absence of nasal symptoms does not preclude the presence of sphenoiditis.11 Significant physical findings are usually absent, although the presence of neurological findings would suggest an intracranial complication.
Any of the structures related to the sphenoid sinus can be affected by pathological processes involving the sinus, in particular cranial nerves II, III, IV, V1, V2, and VI, dura mater, pituitary gland; cavernous sinus; internal carotid artery, sphenopalatine ganglion, sphenopalatine artery, and pterygoid canal and nerve. Sphenoid sinusitis can thus lead to orbital cellulites and abscess, orbital apex syndrome, blindness, sepsis, meningitis, epidural and subdural abscess, cerebral infarction, pituitary abscess, cavernous sinus thrombosis, sepsis, and internal artery thrombosis.22
Various predisposing factors for acute sphenoiditis have been identified. These include anatomical obstructions such as abnormally placed or small sphenoid ostiums, septal deviation, and large superior or middle turbinates.4 Injuries (blunt, penetrating, or surgical) have been shown to lead to infection because of altered drainage patterns and direct inoculation of pathogenic organisms.1,2 Swimming or diving with forceful water entry into the nose has also been linked to acute sphenoiditis.5 Other predisposing factors include radiotherapy, immunosuppression, sinonasal polyps,23 primary metastatic tumors,6,24 ostium obstruction caused by mucosal edema from an upper respiratory tract infection, and allergic rhinitis.11
Acute sphenoiditis is most commonly caused by Staphylococcal aureus, followed by Streptococcal species.2,12,15,25 Gram-negative and anaerobic organisms areoccasionally cultured.2,13,24,25 Although in acute sphenoid sinusitis, predominance of aerobe and anaerobe streptococcus was observed, in chronic sinusitis gram (−), bacillus predominance was seen. Fungi, especially Aspergillus, must be considered in all patients particularly if the patient is immunocompromised.5 Our patient completely recovered without antifungal therapy: hyphal elements probably represented colonization in a previously chronic diseased sinus cavity complicated by a Staphylococcus constellatus infection.
The diagnosis of acute sphenoiditis presents various diagnostic dilemmas. The most common feature of sphenoid sinus disease is difficulty in its diagnosis based on history and physical examination alone. Flexible nasendoscopy may reveal purulent drainage from the sphenoid ostium or in the nasopharynx. The diagnostic study of choice is a high-resolution CT scan (axial and coronal views). This may reveal the presence of fluid (or opacification) and delineate the walls of the sphenoid sinus. In sphenoid sinusitis, there is usually no bony erosion, as in our case, compared with malignant disease. Magnetic resonance imaging with contrast should be obtained if there are any cranial nerve abnormalities because it is superior to a CT scan in revealing pathology in the cavernous sinus and its adjacent neurovascular structures. The axial and coronal planes of CT, which are applied in bony and parenchymal densities, are demonstrative of cavernous sinus thrombosis.26 The thrombotic formation in sinus is seen as multiple filling defects of sinus in CT with contrast material. If inflammation spreads out to the meninges, cavernous sinus may be seen as dilated or asymmetric.16
Uncomplicated cases of acute sphenoiditis can be resolved with optimal antibiotic therapy if diagnosed and treated early.2,22 Prompt treatment is necessary because delay can result in serious morbidity and mortality.2,12 Specific antimicrobial therapy can be adjusted once the culture results from the cerebrospinal fluid, blood, and sinus aspirates are known: in our case, no bacterial culture was obtained from the sphenoid sinus during sphenoidectomy. The duration of antibiotic treatment is approximately 3 to 4 weeks.12 Topical decongestants and saline irrigation help to promote drainage of the obstructed sinus.
Persistence or progression of disease with development of intracranial complications is an indication for immediate surgical drainage.5 Various approaches to the sphenoid sinus are available. Endoscopic approach to thesphenoid sinus, either directly to its anterior surface or through the ethmoids, is the current method of choice.27,28 In case of limited exposure, the posterior segment of the middle turbinate may be cut to improve accessibility.27
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