Gradenigo’s syndrome is a complication of an otitis media infection and mastoiditis, involving three distinct manifestations: suppurative otitis media infection, facial pain compatible with the distribution of the trigeminal nerve and abducens nerve palsy.
Gradenigo's syndrome, otherwise referred to as Gradenigo-Lannois syndrome and petrous apicitis, primarily arises as a complication following a case of otitis media infection and inflammation of the mastoid air cells of the temporal bone, that has extended to the petrous temporal bone  . Its typical presentation involves pain that follows the distribution of the trigeminal nerve (5th cranial nerve), alongside palsy of the abducens nerve (6th cranial nerve) and otorrhea, the latter resulting from an otitis media infection . Even though the aforementioned triad is considered to be the classical presentation of Gradenigo's syndrome, clinical characteristics of the infection are often diverse; photophobia, fever, excessive secretion of tears and a diminished corneal sensitivity may further complicate the clinical picture. Patients may also present with persistent headaches and some studies even report symptomatology consistent with facial and vestibulocochlear nerve pathology . If left misdiagnosed or untreated, Gradenigo's syndrome can lead to serious neurological complications and death .
Given that Gradenigo's syndrome occurs as a complication of an original otitis media infection that has extended to involve the apex of the petrous temporal bone, the syndrome is currently considered a rare medical entity, since antibiotics started to be used in daily clinical practice.
The first step towards a precise diagnosis of Gradenigo's syndrome is a complete medical history, involving symptomatology and duration thereof and a confirmation of a recent or chronic otitis media infection. Manifestations that include an abducens nerve palsy, pain along the distribution of the trigeminal nerve and an otitis media infection that also involves the discharge of pus greatly direct suspicion towards Gradenigo's syndrome.
Imaging modalities that are used to diagnose the syndrome encompass a computerized tomography scan (CT scan) and a magnetic resonance imaging scan (MRI scan) of the temporal bone. The former usually illustrates hypodensity in the region of the petrous apex; the latter is expected to display hyperintensity on T2-weighted images and hypointensity on T1-weighted images. The infected region is enhanced in both the CT and the MRI scan. An MRI scan can also exhibit the pathology that underlies Gradenigo's syndrome and can range between cholesteatomas, malignant tumors, inflammatory granulomas and osteomyelitis  . A single study also implemented diffusion-weighted MRI to aid in the depiction of abscesses and cholesteatomas in regions where diffusion is limited .
The differential diagnosis of Gradenigo's syndrome also entails various other pathologies that can assume the same symptomatology. Nasopharyngeal carcinoma and lymphoma of the petrous bone are two conditions whose symptomatology can greatly resemble that of Gradenigo's syndrome. Attention should be brought to the possibility of afebrile, non-otological manifestations after infectious petrositis, which could be misdiagnosed as a malignancy, with the consequence of antimicrobial treatment postponement influencing the prognosis .