|Year : 2021 | Volume
| Issue : 2 | Page : 379-382
Pseudo orbital apex disorders: Two case reports
Paromita Dutta, Prateek Kumar, Vaibhav Nagpal, Kamlesh Anand, Avani Hariani, Ashish Krishnan
Guru Nanak Eye Centre, Maulana Azad Medical College, New Delhi, India
|Date of Submission||23-Jul-2020|
|Date of Acceptance||07-Oct-2020|
|Date of Web Publication||01-Apr-2021|
Dr. Paromita Dutta
Flat 501, Tower 11, Lotus Panache, Sector 110, Noida - 201 304, Uttar Pradesh
Source of Support: None, Conflict of Interest: None
Multiple cranial nerve palsies are clinical conundrums that can be solved by determining zones of the proximity of the affected nerves. The affliction of two or more contiguous neuroanatomic structures helps in the localization of the causative lesion. However, there are certain caveats to this method of estimation when it may not be applicable such as in cases of multifocal or diffuse pathologies and large mass lesions. Orbital apex disorders refer to the clinical spectrum arising from lesions in the orbital apex, superior orbital fissure, and cavernous sinus. Besides, large neoplasms in the middle cranial fossa too may have a similar presentation. It is essential to consider the possibility of false localizing signs, as is highlighted in our two case reports, both of which initially appeared to be caused by orbital apex region lesions.
Keywords: Cranial nerve, localization, meningioma, schwannoma, subarachnoid
|How to cite this article:|
Dutta P, Kumar P, Nagpal V, Anand K, Hariani A, Krishnan A. Pseudo orbital apex disorders: Two case reports. Indian J Ophthalmol Case Rep 2021;1:379-82
|How to cite this URL:|
Dutta P, Kumar P, Nagpal V, Anand K, Hariani A, Krishnan A. Pseudo orbital apex disorders: Two case reports. Indian J Ophthalmol Case Rep [serial online] 2021 [cited 2021 Jul 29];1:379-82. Available from: https://www.ijoreports.in/text.asp?2021/1/2/379/312374
Many pathological conditions present with or are associated with multiple cranial nerve (CN) palsies. Classically described clusters involving CNs occur in areas like the orbital apex (OA) and cavernous sinus (CS) region, cerebellopontine angle, the jugular foramen, and petrous apex. Localization of the causative pathology allows direct imaging, faster confirmation of diagnosis, and timely initiation of appropriate therapy. Preoperative localization was even more important in the earlier days before the advent of modern radio imaging.
The most common kind of simultaneous multiple CN palsies an ophthalmologist encounters, involves CN II, III, IV, V1, V2, and VI in varying combinations. The causative lesion is commonly found in the region of the OA. The OA represents a unique area in orbital anatomy due to the proximity of important CN, vessels, and muscles. Disorders involving the apex were previously classified based on their locations as OA syndrome (OAS), superior orbital fissure syndrome (SOFS), and CS syndrome (CSS). The clinical distinction between these three conditions was made by the absence of optic neuropathy in SOFS and CSS. CSS may have V2 involvement (depending on the extent of the lesion) and sympathetic disturbance. However, due to overlapping features, similar causes, and management protocols these three conditions are grouped as OA disorders (OAD).
OAD present with varying degree of motility limitation, proptosis, ptosis, hypoesthesia over forehead, cornea, eyelids and cheek, and Horner's syndrome. The associated proptosis may occur due to retro-orbital mass lesions, loss of extraocular muscle tone after oculomotor palsy, or venous congestion.
While CS lesions account for up to 25% of multiple CN palsies, another less common site is the subarachnoid space. All the ocular motor nerves and the trigeminal nerve pass through the subarachnoid cisternal space before crossing over or below the petroclinoid ligament, into the CS. Tumors large enough to encroach upon this space and the intracranial part of the optic nerve and/or chiasma can cause varying grades of ophthalmoplegia along with optic neuropathy.
We highlight two such cases presenting as pseudo OAD.
| Case Reports|| |
A 40-year-old woman presented with gradual and progressive diminution of vision in her right eye (RE), associated with drooping of the upper lid for 6 months. She had been suffering from holocranial headaches for 2 years with worsening severity over the past 2 months. She also complained of left-sided facial weakness for the past 6 months. On examination, the patient had severe ptosis and complete ophthalmoplegia in the RE [Figure 1]. The RE had a mild proptosis (2 mm), anisocoria, and an afferent pupillary defect (APD). She could not perceive light in the RE while the left eye (LE) had a best-corrected visual acuity (BCVA) of 20/30. There was a marked loss of sensations along with the distributions of ophthalmic and maxillary branches of the trigeminal nerve, on the right side. On fundus examination, the RE had primary optic atrophy while the left optic nerve head appeared normal. Automated perimetry of the LE revealed scattered depressed points in the inferotemporal quadrant. On neurological examination, there was a left-sided lower motor neuron (LMN) type facial palsy (House Brackmann Grade 2). However, there was no evidence of any other CN deficit, cerebellar signs, or focal neurological deficit. General physical examination and routine hematological investigations were within normal limits.
|Figure 1: Composite image showing complete ptosis and ophthalmoplegia associated with anisocoria in the right eye|
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Magnetic resonance imaging (MRI) of the brain and orbits revealed a large extra-axial dural-based contrast-enhancing mass in the right medial temporal fossa with perilesional edema [Figure 2]a, [Figure 2]b, [Figure 2]c, [Figure 2]d. The lesion was associated with significant mass effect, the indentation of the right cerebral peduncle, compression over the right optic nerve, and chiasma. There were partial encasement and displacement of the right intracranial internal carotid artery (ICA) along with minimal contralateral midline shift. These radiological features were suggestive of a meningioma.
|Figure 2: (a) MRI T2W image (axial section) shows a large, extra-axial dural-based mass in the medial temporal fossa, appearing iso to hyperintense, causing mass effect with indentation over right cerebral peduncle. (b) T2W image (sagittal section) shows mass compressing right optic nerve. (c) Contrast-enhanced (CE) T1W image (coronal section) shows compression of the chiasma, effacement of lateral ventricle, and small contralateral midline shift (3.5 mm). (d) CE T1W image (axial section) shows encasement of the right intracranial internal carotid artery (arrow), absence of orbital invasion, and dural tail sign (arrowhead)|
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After a neurosurgery consult, the patient underwent a right fronto-temporo-zygotomy with tumor excision. Intraoperatively, the tumor was found to be arising from the medial sphenoid wing. It had a well-defined plane of cleavage and was encasing the ICA, middle cerebral artery (MCA), and anterior cerebral artery (ACA) at their origin. A part of the tumor adherent to CN II and III was left behind. Histopathology confirmed the mass as a meningioma with microcystic changes, World Health Organization (WHO) grade 1.
There has been an improvement in ptosis and ocular motility in the RE, 6 months after surgery. Visual acuity remained unchanged in both eyes and visual field defects in the LE normalized. The left-sided facial palsy also improved.
A 16-year-old girl complained of gradual onset diminution of vision and foreign body sensation in her LE for 1 year. There was associated recent-onset drooping of the left upper lid along with the limited movement of the eyeball. She also experienced episodes of poorly localized headaches. BCVA was 20/20 in the RE and counting fingers at 2 m in the LE. On examination, there was severe ptosis with partial palsy of CN III, IV, and VI [Figure 3]. The pupillary assessment revealed relative APD and anisocoria in the LE. The LE had markedly diminished corneal sensation with punctate epithelial keratopathy and decreased tear film secretion (4 mm on Schirmer's test). There was significant hypoesthesia along with the distribution of ophthalmic, maxillary, and mandibular divisions of CN V with decreased power in the jaw muscles. On fundus evaluation, the right optic disc appeared normal, while there was primary optic atrophy in the LE. There was no other associated neurological deficit. Systemic and routine blood investigations were normal.
|Figure 3: Composite image showing severe ptosis, partial ophthalmoplegia involving CN III, IV, and VI in the left eye (LE). Evident circumcorneal congestion secondary to marked trigeminal dysfunction is also seen in LE|
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MRI brain showed a well-defined extra-axial mass arising from the left prepontine cistern, showing heterogeneous enhancement with contrast [Figure 4]a, [Figure 4]b, [Figure 4]c, [Figure 4]d. The mass was extending up to the left maxillary sinus, superior orbital fissure (SOF), and compressing the optic nerve anterosuperiorly. Medially, there was compression of the midbrain and pons. The mass was also compressing the left CS, Meckel's cave (MC), and deviating the left ICA to the right. There was a midline shift of 15 mm to the right. Posteriorly, the mass was compressing the left cerebellar peduncles and fourth ventricle causing upstream dilatation of bilateral ventricles. These features were suggestive of a schwannoma involving CN V. The patient underwent a shunt procedure followed by a left frontotemporal craniotomy and near-total tumor removal. Intraoperatively the encapsulated tumor was found to be encroaching into the tentorium and CS, and petrous bone was eroded. Histopathological analysis of the tumor was consistent with schwannoma.
|Figure 4: (a) MRI T2W image (axial section, fat suppression) shows a large extra-axial mass, arising from the left prepontine cistern, compressing midbrain and pons; extending to left superior orbital fissure. It is also compressing the left cavernous sinus and Meckel's cave, and deviating the left intracranial internal carotid artery (ICA) towards the right. (b and c) T2W (sagittal sections) show the mass reaching up to the maxillary sinus and compressing the left optic nerve. Also seen is dilated third and lateral ventricle. (d) Computerized tomography shows erosion of petrous bone (arrow) by a dumb-bell shaped mass|
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Visual acuity remained unchanged in both eyes 6 months after surgery. There has been a mild improvement in the degree of ptosis and ocular motility. The patient still has moderately severe dryness in her LE and needs frequent topical lubricants.
| Discussion|| |
Localization of a causative lesion in neurology is based on determining the minimal area of neuroanatomical involvement required to explain the clinical signs. However, these rules for localization may not be applicable in large tumors when different areas may be simultaneously compressed with associated raised intracranial pressure. A false localizing sign has been described as a neurological sign where there is dysfunction distant from the expected anatomical locus of pathology. When a tumor produces signs which are anatomically and physiologically local, but distinctly unusual, they are considered “neighborhood signs.”
Keane found the tumor to be responsible for 30% of cases with multiple CN palsies. Of these, meningioma and schwannoma accounted for 13% and 17%, respectively. The subarachnoid region was the fifth most commonly associated locus in multiple CN palsy (10%), after CS, brain stem, non-localized neuropathy, and skull base-clivus region. The pathway of CN III, IV, VI, and V all have a cisternal (subarachnoid) segment after emerging from the brain stem at different levels. [Figure 5] The cisternal segment of CN III passes through the interpeduncular cistern inferiorly, anteriorly, and laterally, between the posterior cerebral arteries (PCA) and superior cerebellar arteries (SCA). This part, followed by the petroclinoid segment extends up to the oculomotor porus, wherein the nerve pierces the dura to enter the CS. The subarachnoid segment of CN IV emerges on the dorsal aspect of the brain stem, curves around the cerebral peduncles in the ambient cistern, closely related to the tentorium cerebelli. Thereafter, its course is parallel to CN III and it too passes between the SCA and PCA, before entering the lateral wall of the CS. The cisternal segment of CN VI ascends within the prepontine cistern traveling vertically along the clivus. It then pierces the dura and turns anteriorly over the edge of the petrous pyramid, through Dorello's canal and under petrosphenoid (Gruber's ligament) entering the CS. The roots of CN V travel anteriorly through the prepontine cistern, along the medial aspect of the petrous apex, and enter a dural compartment called the MC. The MC is located in the superomedial part of the petrous apex, where it houses the trigeminal ganglion. The dural roof of the MC continues as the lateral wall of the CS. At its anterior border, the trigeminal ganglion divides into three major divisions: ophthalmic (V1), mandibular (V2), and maxillary (V3).
|Figure 5: Sagittal section of the brainstem and middle cranial fossa at the level of midbrain and pons. Cranial nerves (CN) are labeled as they emerge from the brainstem. The common subarachnoid portion of these nerves is shown within the oval zone|
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The middle cranial fossa (MCF) has a butterfly shape when viewed from above. This fossa consists of paired structures fusing medially to form the sella turcica. The CS lies on either side of the sphenoid bone extending from the SOF to the petrous temporal. The chiasma lies anterior to the sellar tuberculum, related posteriorly to the interpeduncular cistern. CN III-VIII all traverse the MCF after emerging from the brainstem. The MCF is at a higher plane than the posterior cranial fossa. Besides, the narrow median part, makes it easy for medial masses to reach the brainstem. Large lesions in the MCF can affect these nerves simultaneously or sequentially by multiple mechanisms. These include compression in the subarachnoid space, external compression/invasion of the CS, and secondary extension up to the OA or SOF.
Medial sphenoid wing meningiomas frequently cause optic neuropathy, on account of proximity, either by direct compression or invasion into the optic canal. CN III is the second most commonly affected nerve and is also prone to iatrogenic injury (during surgery). Winterkorn and Bruno described oculomotor palsy in a case of posterior fossa meningioma. They attributed the palsy to stretching of the oculomotor nerve within the subarachnoid space as it emerged from the brainstem in the interpeduncular fossa. Meningiomas are known to cause false localizing signs by displacing, stretching, and brainstem distortion. CS involvement is also associated with these tumors. Tumor cells have been found to infiltrate into the encompassed CN in select cases.
Trigeminal schwannomas with components in both middle and posterior cranial fossa are typically dumb-bell shaped. These lesions classically present with clinical features of trigeminal dysfunction, as numbness and paresthesia in the distribution of one or all the divisions of the trigeminal nerve, or as facial pain. They may also be associated with motor symptoms like difficulty in chewing and deviation of the jaw, especially in long-standing cases. Additional signs depend on the anatomical site of origin, and the direction and extent of growth. There may also be evidence of bony remodeling in the MCF.
In the first case described, there was no evidence of CS invasion or OA involvement. CN II was compressed in its intracranial segment, whereas CN III, IV, V1, V2, and VI were probably affected in the subarachnoid area. CN VI paresis could also be related to the tumor-related increased intracranial pressure. LMN facial palsy as a false localizing sign has been attributed to brainstem distortion resulting in traction on CN. The second case had additional encroachment of the CS and SOF by an extrinsic tumor, along with tumor-induced compressive optic neuropathy near the OA. The marked evidence of trigeminal hypoesthesia along with motor weakness (muscles of mastication) was due to the tumor itself. Erosion of the petrous apex would also affect CN VI. Despite an initial impression of an OAD, the primary lesion was not at the OA in either of these cases.
| Conclusion|| |
Pseudo OA syndrome due to a mass lesion was first described in a case of cholesteatoma arising from the interpeduncular fossa. Though OAD is rare, considering other possible anatomical loci is imperative, especially in presence of atypical associated signs like facial palsy or marked trigeminal dysfunction. These red flags are markers of a more widespread pathology, calling for even more urgent intervention.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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Conflicts of interest
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