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• Authors' reply
  Isabelle Crassard
  Published on: 9 January 2006
• CT scan technique is unclear from study
  Sanjay Prabhu
  Published on: 29 September 2005
• Headache as the sole manifestation of cerebral venous thrombosis
  Sudhir Kumar
  Published on: 9 August 2005
• CVT present with seizure alone
  Joe Jacob Alappat
  Published on: 20 July 2005

• Published on: 9 January 2006

  Authors' reply

  • Isabelle Crassard
  • Other Contributors:
    • Rodica Cumurciuc, Marie-Germaine Bousser

  Dear Editor,

  We totally agree with Dr Prabhu that CT venography is an excellent tool for the diagnosis of CVT and we indeed occasionally use it but, whenever possible, we prefer the combination of MRI/MRV. The obvious advantage of the MRI is the direct visualization of the clot itself with its different signals according to the duration of thrombosis. It can also show, more precisely than CT scan, the associated cer...

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  Dear Editor,

  We totally agree with Dr Prabhu that CT venography is an excellent tool for the diagnosis of CVT and we indeed occasionally use it but, whenever possible, we prefer the combination of MRI/MRV. The obvious advantage of the MRI is the direct visualization of the clot itself with its different signals according to the duration of thrombosis. It can also show, more precisely than CT scan, the associated cerebral lesions and potential underlying local causes. The most frequently used MRV techniques in our center is time of flight protocol with 3-D examination. As regards patients presenting at onset with neuroimaging, abnormalities suggestive of venous infarctions or haemorrhages, they were by definition excluded for this study.

  Kumar et al had some questions about the methods of selection of the patients in our study. In the methods section, we indicated that patients were included if CT scan did not show any intracerebral parenchymatous lesion. Hyperdensity of a thrombosed sinus was not considered as an intracerebral lesion. Moreover it is indeed a good sign but sometimes difficult to interpret particularly in the emergency department where such patients are usually first seen. Moreover it partly depends on the quality of the CT scan and for lateral sinus thrombosis, it may be misinterpreted as blood. Papilledema was assessed using ophthalmoscopy by neurologists trained to look at fundus in the setting of our headache emergency center and stroke unit. No fluorescein angiography was performed since this is not a routine examination in patients with headache and normal fundus at ophtalmoscopy. Furthermore, most of our patients had CSF pressure measurement, and patients with increased pressure were not included in the study.

  Lastly, SAH was carefully excluded in our patients: normal CSF spectrophotometry and no SAH on flair SW MRI (another advantage of MRI examination in CVT). Most of our patients had indeed lateral sinus thrombosis. Examination by an ENT specialist is systematically performed in all patients with lateral sinus thrombosis and no patient in this series had an ENT infection. We are well aware of the possible misdiagnosis of CVT patients with lateral sinus hypoplasia and have discussed it in our paper: we required for diagnosis of CVT the association of an absence of flow on MRV and an increased signal on MRI T1- and T2-weighted images.[1] Furthermore, we also rely on the MRI T2* sequence which shows the thrombosed sinus as an hyposignal. We have recently shown that it is the most sensitive MRI sinus abnormality in CVT.[2] By contrast angiography is of little help in differentiating lateral sinus thrombosis and hypoplasia. We recently published a study on D-dimers measurements at the acute phase of CVT. D-dimers were normal (less 500 ng/ml) in 25% of patients presenting with isolated headaches indicating that normal D-dimers levels do not exclude CVT in patients with isolated headaches.[3] By contrast, in those presenting with other neurological signs (deficits, seizures, disorders of consciousness), D-dimers are indeed elevated.

  Lastly, all of our patients had repeated MRI and MRV studies and not all patients had recanalisation. The absence of recanalisation can in no way represent a retrospective diagnosis criteria since it has long been recognised that roughly only half of patients with a good clinical outcome recanalise their sinuses.[4]

  Finally, we would like to thank Drs Alappat and Sampath for their personal experience in CVT management. We know that Indian neurologists have a wide experience of CVT and that they have made seminal contributions to this topic. We totally agree with their comments particularly as regards the good prognosis with anticoagulant treatment (heparin followed by coumadine) which has long been our treatment of choice.[5]

  References

  1- Mas JL, Meder JF, Meary E, Bousser MG. Magnetic resonance imaging in lateral sinus hypoplasia and thrombosis. Stroke. 1990;21:1350-1356

  2- Idbaih A, Boukobza M, Crassard I, Porcher R, Bousser MG, Chabriat H. MRI of clot in cerebral venous thrombosis: high diagnostic value of susceptibility-weighted images. Stroke, in press.

  3- Crassard I, Soria C, Tzourio C, Woimant F, Drouet L, Ducros A, Bousser MG. A negative D-dimer assay does not rule out Cerebral Venous Thrombosis: A Series of Seventy-Three Patients. Stroke 2005; 36:1716-1719

  4- Baumgartner RW, Studer A, Arnold M, Georgiadis D. Recanalisation of cerebral venous thrombosis. J Neurol Neurosurg Psychiatry. <javascript:AL_get(this, 'jour', 'J Neurol Neurosurg Psychiatry.');> 2003; 74: 459-61.

  5- Bousser MG. Cerebral venous thrombosis: nothing, heparin, or local thrombolysis? Stroke. 1999; 30:481-3.

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  Conflict of Interest:
  None declared.

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• Published on: 29 September 2005

  CT scan technique is unclear from study

  • Sanjay Prabhu, Specialist Regsitrar in Radiology

  Dear Editor,

  I read with interest the article looking at headache as an isloated symptom of venous thrombosis. As a radiologist, I was interested in the assertion that a "normal CT scan" necessitated a MRI/MRV scan. In my experience if the symptomatology is atypical, performing a CT venogram, particularly on the multislice CT scanner can give an accurate result in a large proportion of cases. We perform CT venog...

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  Dear Editor,

  I read with interest the article looking at headache as an isloated symptom of venous thrombosis. As a radiologist, I was interested in the assertion that a "normal CT scan" necessitated a MRI/MRV scan. In my experience if the symptomatology is atypical, performing a CT venogram, particularly on the multislice CT scanner can give an accurate result in a large proportion of cases. We perform CT venography on a 16 slice scanner and the multiplanar reconstructions of the 1.25mm images in sagittal and coronal reformats enables visualisation of the venous sinuses adequately.

  Secondly, what technique was used for MRV studies? A difference can be seen if phase contrast technique (more accurate) is used in preference to time of flight protocol. Also, 3-D MR venography is often superior to 2D MR venography in the delineation of major cerebral venous structures in children, because artifactual loss of signal is seen with the use of 2D MR venography in nondominant transverse sinuses.

  Thirdly, mention should be made of cases which can present on unenhanced CT with areas of infarction secondary to venous thrombosis and further imaging may be directed accordingly in these cases.

  References

  1. Leach JL, Jones BV, Tomsick TA, Stewart CA, Balko MG. Normal appearance of arachnoid granulations on contrast-enhanced CT and MR of the brain: differentiation from dural sinus disease. Am J Neuoradiol 1996; 17:1523-32.

  2. Casey SO, Alberico RA, Patel M, Jimenez JM, Ozsvath RR, Maguire WM, et al. Cerebral CT venography. Radiology 1996; 198:163-70.

  3. Ayanzen RH, Bird CR, Keller PJ, McCully FJ, Theobald MR, Heiserman JE. Cerebral MR venography: normal anatomy and potential diagnostic pitfalls. Am J Neuoradiol 2000; 21:74-8.

  4. Huisman TA, Holzmann D, Martin E, Willi UV. Cerebral venous thrombosis in childhood. Eur Radiol 2001; 11:1760-5.

  5. Rollins N, Ison C, Reyes T, Chia J.- Cerebral MR venography in children: comparison of 2D time-of-flight and gadolinium-enhanced 3D gradient-echo techniques- Radiology. 2005 Jun;235(3):1011-7. Epub 2005 Apr 28.

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  Conflict of Interest:
  None declared.

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• Published on: 9 August 2005

  Headache as the sole manifestation of cerebral venous thrombosis

  • Sudhir Kumar, Consultant Neurologist
  • Other Contributors:
    • Sndhya, G Rajshekher, Subhashini Prabhakar

  Dear Editor,

  We read with interest the recent article by Bousser et al., where they report a series of 17 patients with cerebral venous thrombosis (CVT) presenting with headache alone. However, we would like to make certain observations.

  Firstly, nine patients (60%) had abnormal computerized tomography (CT) findings (hyperdensity of one or more sinuses), however the authors mention, in the “Methods” sectio...

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  Dear Editor,

  We read with interest the recent article by Bousser et al., where they report a series of 17 patients with cerebral venous thrombosis (CVT) presenting with headache alone. However, we would like to make certain observations.

  Firstly, nine patients (60%) had abnormal computerized tomography (CT) findings (hyperdensity of one or more sinuses), however the authors mention, in the “Methods” section, “normal brain CT” as one of the inclusion criteria.

  Secondly, the authors mention that all their patients had headache without any evidence of intracranial hypertension or subarachnoid haemorrhage (SAH). Regarding intracranial hypertension, what was the method used for assessing papilloedema? Was it done using an ophthalmoscope or fluorescein angiography; by a Neurologist or an Ophthalmologist? The sensitivity of papilloedema detection would vary according to the modalities used. Moreover, benign intracranial hypertension has earlier been reported to occur in the absence of papilloedema too.[2] Similarly, 2.5-5% of patients with SAH may have normal brain CT. These cases require other investigations including digital subtraction angiography or CSF spectrophotometry for the diagnosis.[3] Inadequate investigations may have led to some of the patients with intracranial hypertension and SAH being labelled as CVT.

  Finally, authors found a high proportion of cases with lateral sinus involvement (15/17 cases). Did the patients have any past or present evidence of mastoiditis or otitis media, as these conditions could lead to lateral sinus thrombosis (LST). Moreover, variations in the anatomy of LST are common, including partial or complete absence or dominance of the lateral sinus on one side, which could give rise to flow gaps in the magnetic resonance venography (MRV) leading to a misdiagnosis of dural sinus thrombosis.[4] Therefore, ideally, the patients with LST on MRV required conventional digital substraction angiography to establish the presence of thrombosis. A simpler method to support the diagnosis in acute CVT is D-dimer measurement, and a value above 500 ng/ml supports the diagnosis.[5] Another method of being sure of thrombosis would have been to repeat the MRV study after treatment to show a partial or complete recanalization of the thrombosed sinus(es).[6]

  References

  1. Cumurciuc R, Crassard I, Sarov M, Valade D, Bousser MG. Headache as the only neurological sign of cerebral venous thrombosis. J Neurol Neurosurg Psychiatry. 2005; 76:1084-7.

  2. Spence JD, Amacher AL, Willis NR. Benign intracranial hypertension without papilloedema: role of 24-hour cerebrospinal fluid pressure monitoring in diagnosis and management. Neurosurgery. 1980; 7:326-36.

  3. Gunawardena H, Beetham R, Scolding N, Lhatoo SD. Is cerebrospinal fluid spectrophotometry useful in CT-negative suspected subarachnoid haemorrhage? Eur Neurol. 2004; 52:226-9.

  4. Ayanzen RH, Bird CR, Keller PJ, McCully FJ, Theobald MR, Heiserman JE. Cerebral MR venography: normal anatomy and potential diagnostic pitfalls. AJNR Am J Neuroradiol. 2000; 21: 74-8.

  5. Lalive PH, de Moerloose P, Loyblad K, Sarasin FP, Mermillod B, Sztaizel R. Is measurement of D-dimer useful in the diagnosis of cerebral venous thrombosis? Neurology. 2003;61:1057-60.

  6. Stolz E, Trittmacher S, Rahimi A, et al. Influence of recanalization on outcome in dural sinus thrombosis: a prospective study. Stroke. 2004;35:544-7.

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  Conflict of Interest:
  None declared.

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• Published on: 20 July 2005

  CVT present with seizure alone

  • Joe Jacob Alappat, Neurologist
  • Other Contributors:
    • Kumar Sampath

  Dear Editor,

  I read your well made article with great interest. This condition is very common in our institution, consisting about three to five admissions per month or even more in the summer months. A vast majority are in the post partum period patients. This condition is especially high here probably due to some socio-cultural habits of the inhabitants. The beliefs they enact are withholding fluid intake in the...

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  Dear Editor,

  I read your well made article with great interest. This condition is very common in our institution, consisting about three to five admissions per month or even more in the summer months. A vast majority are in the post partum period patients. This condition is especially high here probably due to some socio-cultural habits of the inhabitants. The beliefs they enact are withholding fluid intake in the postpartum period as well as smoking them with herbal fumes to prevent infections based on their local customs.

  They present to the emergency department with seizure, motor weakness, signs of raised intracranial tension secondary to sinus venous thrombosis. A group of patients present only with seizures. The seizures are often focal, which are ultimately localised to the site of venous infarcts. We also see numerous patients with involvement of the deep venous system as well. Diagnosis is made from clinical suspicion, clinical examination and MR imaging of the brain with MR Angiogram. They do extremely well with anticoagulation. A large percentage of them were found to have procoagulant states.

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  Conflict of Interest:
  None declared.

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