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The syndrome of non-thrombotic superior sagittal sinus occlusion is an uncommon complication of local neoplastic disease which presents clinically as chronic intracranial hypertension without focal signs.1 A few cases have been reported as complications of midline tumours involving the occipital region such as Ewing’s sarcoma, plasmocytoma, neuroblastoma, and disseminated carcinoma of the breast.1-4
To our knowledge, this is the first case report in which this complication appeared secondary to a non-Hodgkin’s lymphoma.
A 36 year old man presented with a subcutaneous mass in the occipital region of the scalp which had increased in size during the past year. His medical history was unremarkable.
The tumour was painless, hard, and fixed to underlying tissue. Neurological examination was normal, except for bilateral papilloedema. Visual acuity was normal. Cranial MRI disclosed an occipital subcutaneous tumour 10×8×3 cm in diameter. Surrounding bone was thickened, and part of the mass extended extradurally, causing displacement of the venous sinuses. Normal signal void in the superior sagittal sinus in T1 weighted images was replaced by a hyperintense signal (figure, A). Complete coagulation studies were normal. The tumour biopsy disclosed a non-Hodgkin’s lymphoma and extension study showed a metastatic lesion in the right femur, confirmed by biopsy.
The patient was treated with local radiotherapy and chemotherapy (six sessions CHOP (cyclophosphamide, doxorubicin, vincristine, prednisone)).
The subcutaneous mass had disappeared two months later. At one year follow up the patient did not complain of neurological or ophthalmological symptoms, and recent MRI and magnetic resonance angiography showed the absence of occipital tumour and superior sagittal sinus occlusion (figure, B).
The syndrome of non-thrombotic occlusion of the superior sagittal sinus, first described by Plant et al,1consists of compressive occlusion of dural venous sinuses secondary to midline tumours in the occipital region of the skull. The clinically distinctive feature is the lack of focal signs in the course of chronic intracranial hypertension.
The most common thrombotic occlusion of the superior sagittal sinus is an acute disorder, usually with disturbance of consciousness and focal signs, including seizures and paresis.5 Reported cases of occlusion of the superior sagittal sinus associated with neoplastic disease have usually been examples of thrombotic complications secondary to hypercoagulability states.
The syndrome of non-thrombotic occlusion of the superior sagittal sinus occurs when a tumour produces an extradural tissue mass beneath the inner table of the skull, and it is difficult to differentiate between compressive occlusion of the superior sagittal sinus or tumour invasion of the dura and sinus. Cerebral angiography may help in such differentiation, but unfortunately, this examination was not performed in our patient.
This complication has not been described in tumours that commonly give rise to bone metastases such as carcinoma of the bronchus, which develop expanding lythic lesions in the skull with minimal soft tissue involvement. Previous cases of non-thrombotic occlusion of the superior sagittal sinus have been reported secondary to solitary plasmocytoma, Ewing’s sarcoma, disseminated carcinoma of the breast, and neuroblastoma,1-4 which, as in our case, all present significant involvement of soft tissue.
It is also worthy of mention that the site of first clinical manifestation in our patient, the skull, is suggestive of metastases rather than that of a primary intracranial neoplasm as confirmed on further scanning. Moreover, the excellent response to standard chemotherapy suggests a systemic vascularisation of this tumour.
The site of compression of the superior sagittal sinus in nearly all the reported cases, including the present patient, is the terminal portion of the superior sagittal sinus and the torcular herophili.1 The chronic course of the sinus compression allows the formation of good colateral venous return, making this process clinically silent.
In conclusion, we report a new cause of non-thrombotic occlusion of the superior sagittal sinus, and emphasise that this syndrome should be considered in cases of midline occipital neoplasms presenting with raised intracranial pressure without focal signs.