|Year : 2006 | Volume
| Issue : 4 | Page : 767-770
|Spontaneous vertebral artery dissection
A Atre, M Jagtap, A Nanivadekar, S Vaid, S Rawat
Department of Imaging, Ruby Hall Clinic, Pune, India
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|Date of Submission||03-May-2005|
|Date of Acceptance||10-Jun-2006|
Keywords: Spontaneous vertebral artery dissection, M.R.I., M.R. angio, Diffusion weighted imaging, lateral medullary infarct
|How to cite this article:|
Atre A, Jagtap M, Nanivadekar A, Vaid S, Rawat S. Spontaneous vertebral artery dissection. Indian J Radiol Imaging 2006;16:767-70
|How to cite this URL:|
Atre A, Jagtap M, Nanivadekar A, Vaid S, Rawat S. Spontaneous vertebral artery dissection. Indian J Radiol Imaging [serial online] 2006 [cited 2019 Aug 22];16:767-70. Available from: http://www.ijri.org/text.asp?2006/16/4/767/32343
| Case report|| |
A 42 years old lady presented in Neurology OPD with tingling numbness on left side of body and ataxia. There was no history of trauma.
On clinical examination no neurological deficit was found.
Imaging: M.R.I. of the Brain was performed by taking Spin Echo T1 weighted Sagittal, Axial, PD / T2 weighted Axial and FLAIR sagital and Coronal images.
In addition diffusion weighted images and ADC maps were obtained.
On flair images hyperintense signal was seen in the left half of medulla and lower part of the pons.
These areas were hardly bright on Diffusion weighted images. No cerebellar lesions were seen.
Both cerebral hemispheres were absolutely normal.
The left vertebral artery showed hyperintense signal in its wall at the level of arch of C1, (Crescent sign). The distal part of the left vertebral artery did not show the expected flow void and appeared slightly smaller as compared to its counterpart. A possibility of vertebral artery dissection was raised and was confirmed on Fat suppressed T1W images & 3D TOF MR angiogram obtained subsequently.
3D TOF angiogram obtained through the region of neck vessels, base of skull showed narrowing of the left vertebral artery. Right vertebral artery looked normal. Both common carotid arteries and their bifurcations showed normal appearance. Both internal carotids and external carotids showed normal flow.
All these imaging findings are consistent with left vertebral artery dissection leading to ischemia in the left half of medulla and lower part of the pons.
Catheter angio was not done in this patient. Patient was treated with anticoagulants and recovered completely in next two days.
| Discussion|| |
Spontaneous vertebral artery dissection is a rare condition.
The frequency of spontaneous V.A. dissection is one third that of spontaneous internal carotid artery dissection. It is less common than dissection linked to known causes. ,,,,
Various described predisposing factors are: 
1. Fibromuscular disease
2. Connective tissue disease
5. Oral contraceptive use.
Common Clinical symptoms and signs with which these patients presented are - Sudden onset of ipsilateral occipital or upper neck headache. (most common) and signs suggestive of brain stem ischemia especially the Lateral Medullary or Wallenberg syndrome.
Common site and vertebral artery involvement is the segment of artery between Atlas More Details and axis (V3) with 20% cases involving intradural (V4) segment. ,
Hypertension is a common association seen in approximately 50% of patients.
Other associated findings are Fibromuscular hyperplasia seen in approximately 15% of patient, most of the times affecting renal artery.
Arteritis & cystic medical necrosis are additional associations.
Prognosis of Patients with spontaneous Vertebral Artery dissection is good & 90% are expected to make an excellent recovery.  Those associated with SAH have guarded prognosis.
| Imaging|| |
Understanding the course and anatomy of the vertebral artery is a key point in properly identifying and locating a vertebral artery dissection. ,
Vertebral artery is composed of 4 divisions.
1. Proximal (V1) from the subclavian origin (ostium) to the C6 transverse foramen.
2. Intraforaminal (V2) - The vertical course from C6 to C2 within the transverse foramina.
3. Atlantoaxial (V3) - The upward and lateral course from C2 to C1 transverse foramina, then curving posterior and medial to the lateral masses to pierce the atlanto-occipital membrane and dura to the foramen magnum.
4. Intracranial (V4) from the foramen magnum to the lower pons where it joins the opposite vertebral artery to form the basilar artery.
Spontaneous dissection affects segment V3 most frequently.
An imaging strategy to identify these dissections centres around MR Angiography because it allows simultaneous assessment of the intracranial contents for haemorrhage, infarction and detection of dissection.
Although angiography continues to be used in many centers, it is an invasive test that carries a 1-3% risk for inducing stroke and worsening a vertebral dissection.
Commonly shows effects of vertebral artery dissection in brain, like lateral medullary syndrome. High signal changes on T2-weighted studies and diffusion weighted images mark the site of acute infarction. MRI can give clue to diagnosis of dissection. ,,
- Significant dissection leads to occlusion of true lumen, which is seen as loss of flow void.
- Axial T1 sequences are particularly helpful in confirming diagnosis especially if crescent sign (ellipticed bright signal within a vessel). The thrombus in the false lumen is often increased in signal intensity on both T1 weighted and T2W spin echo images owing to presence of extracellular methhaemoglobin. This was clearly seen in our patient.
DWI imaging shows acute infarct as increased signal intensity.
Perfusion imaging when performed will be helpful in deciding line of treatment by identifying diffusion / perfusion mismatch and thus tissue at risk of infarction.
(2) MR Angiography:
MR angiography plays important role in the noninvasive diagnosis and monitoring of vertebral artery injury although there are many technical pitfalls which gives false positive diagnosis / false negative study. But such technical pitfalls can be minimized by performing routine spin echo MR imaging in conjunction with MR angiography.
MRA remains the noninvasive method of choice for initial diagnosis and follow up examination for dissection of the vertebral artery.
Demonstration of hypoplasia / developmental narrowing may assist in modifying treatments, including spinal manipulative therapy.
The key imaging signs are: -
a) Luminal narrowing
c) Demonstration of thrombus as high signal on T1W1.
d) Increased external diameter of the vessel
Often the dissection is best detected on the source partition images used for the generation of MR Angiography images. ,(16)
| References|| |
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Department of Imaging, Ruby Hall Clinic, Pune
Source of Support: None, Conflict of Interest: None
[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4], [Figure - 5], [Figure - 6], [Figure - 7]
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