Sixth Nerve Palsy

Sixth Nerve Palsy EsotropiaDouble visionThe patient is a 45 year old pharmaceutical executive who, nine days prior to admission, flew back from San Francisco after a hectic business trip feeling jet lagged and fatigued. Inspite of this, four days later, he did a day trip to New York. On the following morning, a Saturday, he awoke with a severe generalized headache, which persisted for two days. On Monday he was well enough to return to work. The next day he had double vision with objects side-by-side. He came, as an emergency, to the Neuro-Ophthalmology Clinic at the Massachusetts Eye and Ear Infirmary. A diplopia history revealed that • He had diplopia at distance only, not for reading • He experienced difficulty driving a car • He had a single image with one eye covered • The images were side-by-side and became further apart on gaze left. • He did not see an image split into two but when he had diplopia, he could refocus a single image by blinking • He had a past history of diplopia • No history of ptosis • No known squint • He had never worn prism glasses • His last eye examination was four years ago Past History: Negative for headache or head trauma Significant for a transient episode of diplopia eighteen months prior to this. At that time, he did not seek medical advice. Family History: Positive for diabetes in both grandparents Father died of cancer of the colon Mother mild hypertension Neuro-ophthalmological examination: Visual acuity, stereopsis, visual fields, pupils, and fundus examination normal. Ocular motility: No ptosis No exophthalmos Full eye movements right eye (OD) Esotropia (24 diopters) in primary gaze left eye (OS) Limitation of full abduction OS Normal convergence No nystagmus Normal corneal reflexes Lower cranial nerves normal Neurological examination: Normal Hematological studies: Hyperlipidemia Brain CT (October 1990) No evidence of a cavernous sinus lesion or bony destructive changes. Normal study apart from complete opacification of the right mastoid sinus with soft tissue density consistent with mucosal thickening. Diagnosis: Sixth nerve palsy Etiology: The etiology of this presumed recurrent isolated left sixth nerve palsy was unclear. The diplopia resolved spontaneously over a period of four weeks and in view of his significant hyperlipidemia, the palsy was attributed to microinfarction of the sixth nerve. The patient remained free of diplopia until February 1993 when, a few days after a severe upper respiratory infection complicated by sinusitis, he again developed double vision and deviation of the left eye inwards. He was seen in the Neurovisual Clinic at the Massachusetts General Hospital (MGH), for re-evaluation and was found to have an isolated left sixth nerve palsy with esotropia in primary gaze, and failure of the left eye to abduct past the midline. The left third and fourth cranial nerves were normal. He had no other neuro-ophthalmic or neurological findings. A Brain MRI with gadolinium was recommended but the patient declined because of severe claustrophobia. Brain CT with and without contrast: (5/18/93) Post contrast coronal images through the petrous bones, cavernous sinus and orbit were also obtained. High resolution thin section axial and coronal cuts were obtained through these regions. Findings: 1. Examination of the head revealed erosion at the base of the clivus in the midline. The margin appeared to be well corticated and thought to represent erosion at the site of ligamentous attachment. The possibility of primary or metastatic tumor was not completely excluded. 2. Small erosions were noted in the superior aspect of the clivus to the left of the midline adjacent to the petrous apex without well corticated margin. Again tumor at this site was not excluded although similar appearance can be seen related to basilar artery pulsation. 3. The right petrous apex was well pneumatized. The left petrous apex was completely opacified without evidence of bony destruction or definite bony expansion. 4. Opacification of several inferior and posterior mastoid air cells was also noted on the left. MR imaging was strongly recommended for further evaluation. Brain MRI (6/22/93) The study showed: 1. An abnormal T2 bright focus which enhances at the base of the clivus, associated with some erosion of the cortex of the base of the clivus. There was slight mass effect upon the ventral aspect of the descending cord at the craniocervical junction. These was some impingement upon the ventral aspect of the upper spinal cord at this level, best seen on the sagittal pictures. 2. A second more subtle region of possible abnormality near the left brain stem, near the expected region of Dorello's canal, was present with questionable enhancement and some irregularity of the contours suggesting a possible second focus of abnormal involvement of the clivus. 3. Still evidence of membrane thickening in the mastoid air cells but less than previously described representing improvement. 4. Still marked maxillary sinus disease. Impression: The combination of findings suggested the possibility of a multifocal chordoma with predominant lesion at the base, and possibly a second lesion near the tip of the clivus. A second possibility would be metastatic disease. Base of skull x-rays showed: No gross abnormality demonstrated in the clivus. Cervical spine x-rays showed: Degenerative changes at the level of C5-6 but were otherwise normal. Diagnosis: Acute mastoiditis with inflammatory opacification left petrous apex Neurosurgery Consultation: In August 1993 the patient was free of diplopia. He consulted Dr. Robert Ojemann, MGH Neurosurgeon, for his opinion regarding the possibility of a multifocal chordoma of the clivus. Dr. Ojemann was of the opinion that mastoid sinus disease and inflammation of the petrous apex was the most likely cause of the current sixth nerve palsy. He recommended an annual follow-up brain MRI. Brain MRI (11/8/93) T1 weighted sagittal and axial images, T2 weighted fast spin echo axial images, and post-gadolinium axial and coronal images were obtained. The studies were reviewed in comparison with the brain MRI under sedation 6/22/93 and a head CT from 5/18/93. Serial brain MRIs from 1993 to 1998 showed no change in the focus of enhancement at the base of the clivus and no further bone erosion. As a result, it was thought that the focal clival abnormality was very unlikely to represent a clivus tumor. Diagnosis: Recurrent sixth nerve palsy Acute mastoiditis and petrositis Gradenigro's syndromeThis patient had three transient episodes of horizontal diplopia due to a sixth nerve palsy over a period of three years attributed to recurrent sinus disease and petrositis. He gives an excellent diplopia history. He has: • No ptosis • Esotropia OS in primary gaze • Inability to abduct the left eye past the midline • Third and fourth cranial nerves OS normal • Full eye movements right eye • No facial weakness Patching the OD with the patient fixing with OS confirmed the abduction weakness was due to paresis of the lateral rectus muscle innervated by the sixth nerve i.e. a paralytic esotropia.Neuroimages in this patient are not available.After the 6th cranial nerve leaves the arachnoid space, it rests upon the petrous bone and its crest. In this location it is susceptible to trauma (temporal bone fractures) and spread of infections from the underlying mastoid process. These infections can cause petrositis or thrombosis of the inferior petrosal sinus, both of which may affect functions of the adjacent fifth and sixth cranial nerves, with consequent diplopia and facial (usually supraorbital) pain. Gradenigo's Syndrome: The combination of pain in the distribution of the first trigeminal division and ipsilateral abduction weakness (often accompanied by deafness) constitutes Gradenigo's syndrome. This syndrome, now uncommon with infection, may however be encountered in patients with cancer involving the petrous bone.Antibiotic therapy1. Leigh JR, Zee DS. Diagnosis of Peripheral Ocular Motor Palsies and strabismus. Ch 9;385-474. In: The Neurology of Eye Movements 4th Edition, Oxford University Press, New York 2006. 2. Sherman SC, Buchanan A. Gradenigo syndrome: a case report and review of a rare complication of otitis media. J Emerg Med 2004;27:253-256. http://www.ncbi.nlm.nih.gov/pubmed/15388211 3. Villa G, Lattere M, Rossi A, Di PP. Acute onset of abducens nerve palsy in a child with prior history of otitis media: a misleading sign of Gradenigo syndrome. Brain Dev 2005;155-159. http://www.ncbi.nlm.nih.gov/pubmed/15668058curriculum_fellow; MTemspsixthabducens; NOTE-EXAMCN34