Laboratory Studies
The diagnosis of Tolosa-Hunt syndrome (THS) is usually one of exclusion.
CBC count, erythrocyte sedimentation rate (ESR), electrolytes with glucose, thyroid function tests, fluorescent treponemal antibody (FTA), antinuclear antibody (ANA), lupus erythematosus (LE) preparation, antineutrophil cytoplasmic antibody (ANCA), serum protein electrophoresis, Lyme titre, angiotensin-converting enzyme (ACE) level, and HIV titre are helpful in eliminating other processes. This level of evaluation is required to exclude other conditions, which can have significant morbidity associated.
Cell count and differential, protein, glucose, fungal and/or bacterial cultures, Gram stain, cytology, and opening pressure of CSF are helpful in eliminating conditions mimicking THS; a mild (lymphocytic) pleocytosis within the spinal fluid may occur in patients with Tolosa-Hunt syndrome.
Anti-GQ1b antibodies may be helpful in distinguishing early, painless THS from Miller Fisher syndrome.
Imaging Studies
MRI [8] of the brain and orbit with and without contrast, magnetic resonance (MR) angiography or digital subtraction angiography (DSA), and CT scan of the brain and orbit with and without contrast may all be useful (see the images below). Inflammatory changes in the cavernous sinus, superior orbital fissure, and/or orbital apex are typically observed on high-resolution contrast-enhanced imaging. In the authors' experience, thin-slice high–magnetic field MRI of the cavernous sinus region, including coronal sections with and without contrast and fat-suppressed cuts of the orbital regions, is the modality of choice. These changes are not specific for Tolosa-Hunt syndrome and may also be present in neoplastic conditions of the cavernous sinus. Enlargement of the optic nerve or external ocular muscles has been described, emphasizing the continuum with idiopathic orbital inflammatory disorders. [9]
Note that findings on all imaging studies may be normal in some cases of Tolosa-Hunt syndrome.
Narrowing of the internal carotid artery within the cavernous sinus may be identified on angiography. Note that these changes are not specific to Tolosa-Hunt syndrome.
MRI with 3-dimensional constructive interference in steady state (3D CISS) provides an enhanced picture within the cavernous sinus. This type of imaging may assist with future diagnoses of TSH, but it is not yet used routinely. [10]
MRI of a 40-year-old man with severe periorbital pain ocular sinister (OS; ie, left eye), complete oculomotor nerve palsy OS, and partial abducens nerve palsy OS. Axial imaging without (left) and with (right) enhancement demonstrates nonspecific fullness involving the left cavernous sinus, consistent with Tolosa-Hunt syndrome within the context of the history. Treatment with steroids produced complete resolution of symptoms. Image courtesy of Eric Eggenberger, DO.
Coronal T1-weighted MRI with (below) and without (above) enhancement demonstrates left cavernous sinus fullness consistent with Tolosa-Hunt syndrome (THS). The imaging features are nonspecific and must be placed into the context of the history, examination, and clinical course to avoid misdiagnosis of infiltrating, infectious, or neoplastic cavernous sinus processes. Image courtesy of Eric Eggenberger, DO.
Procedures
Biopsy of the lesion may be required to confirm the diagnosis. The technical difficulty of cavernous sinus region biopsies usually mitigates for a trial of steroids; nonetheless, biopsy may be needed to exclude neoplasm or if symptoms are progressing, atypical, or recurrent.
Histologic Findings
Biopsy reveals nonspecific granulomatous or nongranulomatous inflammation. This is histologically indistinguishable from the pathology of orbital pseudotumor, and these diseases may exist along a continuum.
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MRI of a 40-year-old man with severe periorbital pain ocular sinister (OS; ie, left eye), complete oculomotor nerve palsy OS, and partial abducens nerve palsy OS. Axial imaging without (left) and with (right) enhancement demonstrates nonspecific fullness involving the left cavernous sinus, consistent with Tolosa-Hunt syndrome within the context of the history. Treatment with steroids produced complete resolution of symptoms. Image courtesy of Eric Eggenberger, DO.
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Coronal T1-weighted MRI with (below) and without (above) enhancement demonstrates left cavernous sinus fullness consistent with Tolosa-Hunt syndrome (THS). The imaging features are nonspecific and must be placed into the context of the history, examination, and clinical course to avoid misdiagnosis of infiltrating, infectious, or neoplastic cavernous sinus processes. Image courtesy of Eric Eggenberger, DO.
