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Editor,—Maini and MacEwen recently published a report in the BJO 1 of intraorbital optic nerve compression secondary to an intracranial plasmacytoma. Although rare, extramedullary plasmacytomas usually present in the head and neck region,2 and with improved methods of intracranial imaging, it is likely that more of these tumours will be detected at an early stage by the ophthalmologist. Here, we report a similar case of intracranial plasmacytoma but presenting as a rare disorder of ocular motility normally associated with middle ear infection.
A 45 year old man presented to his general practitioner with a sudden onset of horizontal diplopia after blowing his nose vigorously. He was noted to have a mild pyrexia, left frontal sinus pain, and left sided otalgia but was otherwise well. Two years earlier the patient had been diagnosed as having myeloma following the detection of serum and urinary paraproteins in association with lytic lesions of the sternum and femur. At that time he received total body irradiation and a peripheral blood stem cell transplant. Subsequently, the paraproteinaemia and symptoms regressed and the patient was considered to be in remission.
He was referred immediately for an ophthalmological opinion with a provisional diagnosis of middle ear infection. Orthoptic assessment revealed a moderate left esotropia for near (20 prism dioptres) and distance (16 prism dioptres) and a diagnosis of incomplete left lateral rectus palsy was confirmed by a Hess chart examination. Examination was otherwise unremarkable: visual acuity was normal and no afferent pupillary defect or papilloedema could be detected. Close follow up was organised in conjunction with the haematology department, but the following week he re-presented with left sided trigeminal neuralgia, left sided deafness, and dysarthria. Neurological examination suggested involvement of the left V, VI, VIII, X, and XII cranial nerves. A computed tomogram (Fig 1) showed a lytic lesion at the apex of the petrous temporal bone, and subsequent magnetic resonance imaging confirmed the presence of an intracranial lesion extending caudally from the left middle cranial fossa to involve the affected cranial nerves (Fig 2).
The lesion was diagnosed as an extramedullary plasmacytoma and the patient underwent posterior fossa radiotherapy. He fortunately made a rapid improvement, but still had a slight residual diplopia which was alleviated by a prismatic correction. There was no evidence of relapse of his myeloma.
In 1904 Gradenigo described a syndrome of sixth nerve palsy with pain in the distribution of the upper divisions of the trigeminal nerve caused by otitis media and mastoiditis in the region of the apex of the petrous temporal bone.3 In recent times, however, other causes have been recognised—for instance, meningioma, fractures, and T cell lymphoma.4 To our knowledge, this is the first report of Gradenigo’s syndrome caused by an extramedullary plasmacytoma, and almost certainly the first to be confirmed with magnetic resonance imaging.
The possible pathogenesis of this particular case is interesting, since the diplopia occurred suddenly after vigorous nose blowing. In Gradenigo’s original paper, the cranial nerve involvement was thought to occur as a result of gradual spread of middle ear infection upwards to cause inflammation of the meninges overlying the apex of the petrous tympanic bone.3 In this report we believe that the osteolytic plasmacytoma eroded into the apex of the petrous temporal bone, thus weakening the roof to the underlying air cells. The abrupt rise in intra-auricular pressure with nose blowing caused a sudden upward eruption of cells, or dural tear, affecting the sixth nerve and allowing rapid progression of the tumour into the posterior cranial fossa as far caudally as the hypoglossal canal over the following week (Fig 1).
The involvement of the sixth nerve in myeloma is more often an indirect result of raised intracranial pressure or diffuse meningeal infiltration.5 It is important to underline the difference between that condition and the much rarer isolated intracranial extramedullary plasmacytoma described in this report. In the latter, systemic indicators of myeloma are absent, and the prognosis following radiotherapy is far better.
The authors would like to thank Dr C Barton, consultant haematologist, Dr N Derbyshire and Professor D Allison, consultant radiologists, for their help with this case report.