Abstract

Introduction

Acute isolated sphenoid sinusitis (AISS) is a rare and potentially life-threatening form of sinus infection, accounting for approximately 1–2% of all sinusitis cases [1]. In clinical practice, AISS is even less common in the pediatric population compared to adults. The disease is usually of inflammatory origin, while neoplastic causes are exceedingly rare. Diagnosing AISS is often challenging because patients may lack the typical symptoms of acute bacterial rhinosinusitis, such as nasal discharge or fever, as defined by widely accepted diagnostic criteria [2]. However, with the increasing availability of advanced imaging techniques, including computed tomography (CT) and magnetic resonance imaging (MRI), the identification of AISS has become more feasible in recent years. The sphenoid sinus is anatomically surrounded by several vital structures including the dura mater, pituitary gland, cavernous sinus, internal carotid artery, and cranial nerves II, III, IV, V, and VI [3]. Therefore, even a localized infection in this sinus can present insidiously and progress rapidly to severe complications. Headache, particularly in the retro-orbital or vertex regions, is a common presenting symptom. If left untreated, AISS may lead to intracranial sinus thrombosis, cranial nerve palsy, visual loss, meningitis, osteomyelitis of the skull base, intracranial abscess formation, and even death. Ocular cranial nerve involvement represents an uncommon but serious complication, occurring in 6–12% of patients with sphenoid sinusitis [4]. Among these, the abducent nerve is most frequently affected (76%), followed by the oculomotor nerve (18%) [5]. The petrous apex is pneumatized in only about 30% of individuals, and this limited pneumatization contributes to the rarity of petrous apicitis. Gradenigo’s syndrome a distinct form of petrous apicitis characterized by the classical triad of otitis media, retro-orbital pain, and abducens nerve palsy was first described by Giuseppe Gradenigo in 1907 [6]. Although its reported incidence is as low as 0.002%, the syndrome carries the risk of intracranial complications and can be fatal if diagnosis and treatment are delayed [7]. Herein, we report an exceptional case presenting with the coexistence of two extremely rare entities: isolated sphenoid sinusitis and petrous apicitis associated with abducens nerve palsy. To the best of our knowledge, this combination has not been previously described in the literature, highlighting the importance of early recognition and prompt management.

Case Report

A 6 year old male patient having fever, headache, nausea and vomiting was admitted to the emergency outpatient clinic due to a shift in his left eye two weeks ago. Because the patient had neck stiffness, he was referred to the pediatric intensive care unit with a preliminary meningitis diagnosis, lumbar puncture was applied, and antibiotherapy was initiated (intravenous ceftriaxone and vancomycin). The laboratory results of the lumbar puncture were non-pathological. The brain and temporal MRI and brain and paranasal CT demonstrated petrous apicitis, sphenoid sinusitis, and inflammation around the cavernous sinus.

Figure 1 A: Axial section of temporal MRI; the area marked with a blue star indicates the left sphenoid sinus. The area marked with a red arrow shows signal enhancement due to inflammation adjacent to the cavernous sinus. B: Axial section of temporal MRI; the area marked with a green star indicates the petrous apex, while the green arrow points to the mastoid air cells. Effusion due to petrous apicitis and mastoid effusion are notable. C: Coronal section of temporal MRI; the area marked with a blue star shows the left sphenoid sinus. D: Coronal section of temporal MRI; the yellow star indicates the cavernous sinus, and the red arrows show signal enhancement due to inflammation in the area adjacent to the cavernous sinus. (MRI: Magnetic Resonance Imaging)

Figure 2 A, B: Axial sections of temporal CT; red arrows indicate the petrous apex, the blue star indicates the left sphenoid sinus, and green arrows point to the mastoid air cells. Effusion in the petrous apex due to petrous apicitis, increased opacity in the sphenoid sinus due to sphenoid sinusitis, and effusion in the mastoid cells are notable. (CT: Computed Tomography)

Afterward, the patient was consulted with the otolaryngology clinic. In the examination we performed, the nasal endoscopy was normal, and there was fluid in the left middle ear cavity causing a slightly bulging to the left tympanic membrane. By evaluating the examination findings and imaging methods results, the patient underwent bilateral endoscopic transnasal sphenoidotomy and left ventilation tube placement surgical procedures. Cultures were obtained from both the sphenoid sinus drainage and ear fluid, and the bacteriologic study results were negative. Three days after the surgical procedures, the patient's headache regressed, and his general condition, petrous apicitis and sphenoid sinusitis improved; however, the abducens paralysis did not recover.

Discussion

Lesions occurring anywhere along the course between the sixth nerve nucleus in the dorsal pons and the lateral rectus muscle may affect the sixth cranial (abducens) nerve, and paralysis may develop depending on this influence. Abducens nerve has the longest subarachnoid course among all cranial nerves, innervating the ipsilateral lateral rectus muscle of the eye. The sixth nerve palsy in children occurs mostly due to tumors, trauma, increased intracranial pressure, and congenital lesions. In a study including 75 children (average 8 years) diagnosed with sixth cranial nerve palsy, neoplasms or their neurosurgical removals were the most common ethiological cause, including 34 cases (45%) [8]. The most frequent causes of sixth nerve palsy in adults are vascular disease, inflammation, trauma, tumors, and idiopathic cases [9]. In the case we presented, there were two causes of abducens paralysis (sphenoid sinusitis and petrous apicitis), and both were infectious, which could not be counted among the most common causes in children.

Isolated sphenoid sinus infection is rare, but it is prone to complications due to the critical structures in its adjacence. The sphenoid sinus has the adjacency of critical structures. Superiorly, there are the pituitary gland, the middle cranial fossa, and the optic nerve and chiasm. On both sides, the cavernous sinus, the internal carotid artery, and cranial nerves III-VI are localized. Anteriorly, there are the nasopharynx, the pterygoid canals and nerves, and the pterygopalatine ganglion and artery [10]. Due to this adjacency, not only infectious causes but also space-occupying lesions due to compression effects like mucocele, retention cyst, tumors affecting the sphenoid sinus can cause abducens paralysis [11]. Infectious causes are gram-positive and gram-negative microorganisms and fungi that have been pathogenically proven in sphenoiditis. Aspergillus species are determined more frequent in chronic cases [12]. In our case, sphenoid sinusitis was present, but there was no growth in the cultures studied from the purulent material in the sphenoid sinus. When complications are observed in isolated sphenoid sinusitis, antibiotherapy should be initiated immediately, and surgery should be considered. Endoscopic transnasal, endoscopic transethmoid, transseptal and endoscopic pterygoid fossa approaches constitutes the transnasal surgical approaches to isolated sphenoid lesions [3]. The authors in this report preferred an endoscopic transnasal sphenoidotomy for the surgical intervention.

Gradenigo syndrome, a rare disease, has the clinical symptom triad of diplopia (ipsilateral abducens nerve palsy), unilateral retro-orbital pain (trigeminal ganglionitis), and chronic otorrhea As far as examined, the coexistence of these two conditions has never been reported in the literature priorly. (otitis media). Guiseppe Gradenigo first described it in 1907 [6]. Gradenigo syndrome is caused by apical petrositis secondary to suppurative otitis media. Nonetheless, Gradenigo syndrome differs from apical petrositis since only 13-42% of patients would develop the classic symptom triad of Gradenigo syndrome [13]. Staphylococcus, Group A Streptococcus, P aeruginosa, Klebsiella pneumoniae, and Mycobacterium tuberculosis were the organisms that were considered to be associated with infection in Gradenigo syndrome [14]. In our case, there were retroorbital pain, abducens palsy and petrous apicitis, but suppurative otitis was not determined. There was no history of otitis in the patient's medical history. CT revealed petromastoid air cell opacification yet no erosion in the bone tissue. Before final isolated pathogens are revealed, broad-spectrum and early antibiotics should be administered. Aggressive surgical intervention such as drainage of the middle ear, mastoidectomy, or apical petrosectomy should be performed if conservative medical management fails to prevent potential morbidity [13]. In our case ventilation tube was applied because of the fluid appearance in the petrous apex and mastoid cells in the temporal MRI and CT of the patient.

Isolated sphenoid sinusitis and petrous apicitis are extremely rare diseases that infrequently cause paralysis of the sixth cranial nerve. Abducens paralysis cases related to isolated sphenoid sinusitis and petrous apicitis have been reported in the literature separately, but a patient with both is extremely rare, as far as we know. Although most of the abducens paralysis due to these two reasons healed, in our case, the abducens paralysis was permanent despite the healing of sphenoid sinusitis and petrous apicitis.

Conclusion

Acute isolated sphenoid sinusitis and petrous apicitis are rare but potentially serious infections that can cause sixth-cranial-nerve palsy in children. Because these conditions may initially present with only nonspecific symptoms such as headache or diplopia, early recognition is often challenging. Clinicians should maintain a high index of suspicion for sphenoid and petrous apex involvement in pediatric patients presenting with abducens nerve palsy, even in the absence of otologic symptoms. Early imaging and timely surgical management are crucial to prevent permanent neurological deficits and life-threatening complications.

References

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Presented at

This case report has been accepted as an e-poster at the Turkish National Congress of Otorhinolaryngology and Head & Neck Surgery, which was held in Cyprus on November 5–9, 2025.