Vertebral dissection

The incidence of diagnosed internal carotid artery dissection is approximately 1-4 per 100000 per year. Vertebral dissection is a little less common. The actual incidence of dissections is likely to be considerably higher, but the diagnosis is often missed, particularly in older patients. Usually only one artery is involved but in about 10%, multiple arteries... 

Valsalva maneuver (paradoxical embolism, or low flow) Carotid/vertebral dissection (Ch. 6)... 

Any injury in the days and weeks before ischemic stroke or TIA onset is important and may not be spontaneously volunteered by the patient particularly where this occurred some time previously. A head or neck injury might have caused a chronic subdural hematoma (highly unlikely if more than three months previously) or carotid or vertebral dissection (Ch. 6). 

Dissection of the internal carotid and vertebral arteries is a common cause of stroke, particularly in young patients. Although many occur due to trauma, it is estimated that over half occur spontaneously. The mechanism of stroke following arterial dissection is either by artery-to-artery embolism, by thrombosis in situ, or by dissection-induced lumenal stenosis with secondary cerebral hypoperfusion and low-flow watershed infarction. Occasionally, dissection may lead to the formation of a pseudoaneurysm as a source of thrombus formation. Vertebrobasilar dissections that extend intracranially have a higher risk of rupture leading to subarachnoid hemorrhage (SAH). ° ... 

Jacobs A, Lanfermann H, Neveling M, Szelies B, Schroder R, Heiss WD. MRI- and MRA-guided therapy of carotid and vertebral artery dissections. J Neurol Sci 1997 147 27-34. 

Schievink W. The treatment of spontaneous carotid and vertebral artery dissections. Curr Opin Cardiol 2000 15 316-321. 

Dissect the vertebral column. Note the cell bodies of lumbar motor neurons are more rostral than their exit points, i.e., L4 cells bodies are in upper lumbar or even lower thoracic vertebrae, even though the spinal nerve exits at the fourth lumbar vertebrae. The more caudal vertebral column contains only the cauda equina, the dorsal, and ventral roots of lower lumbar and sacral motor neurons (Fig. 20.2). 

Fix the spinal cord in the intact vertebral column using Bouin s fixative, either by immersion after dissection or by transcardial perfusion prior to dissection. The bone of the vertebrae will eventually decalcify in Bouin s (requiring 2-4 weeks), or after 24 h, the sample can be transferred to decalcifying solution overnight. 

Fig. 20.2. The spinal cord and cauda equina. The caudal spinal cord does not completely fill the caudal vertebral column. As a result, the dorsal and ventral roots of lumbar and sacral neurons are very long, spanning from the more rostral cell bodies to the more caudal exit points. Therefore, the dissected spinal cord resembles a horse s tail. The practical effect of this anatomy is that it becomes very hard to reliably determine the level of the spinal cord that is being studied in any given cross-section.

Abstract a-Latrotoxin (a-LTX) from black widow spider venom induces exhaustive release of neurotransmitters from vertebrate nerve terminals and endocrine cells. This 130-kDa protein has been employed for many years as a molecular tool to study exocytosis. However, its action is complex in neurons, a-LTX induces massive secretion both in the presence of extracellular Ca2+ (Ca2+e) and in its absence in endocrine cells, it usually requires Ca2+e. To use this toxin for further dissection of secretory mechanisms, one needs an in-depth understanding of its... 

Spontaneous dissection of the internal carotid or the vertebral artery is an important cause of ischemic stroke in young adults (Fig. 1.3). In the late 1970s Fisher et al. (1978) and Mokri et al. (1979) described dissections of carotid and vertebral arteries as detected by modern diagnostic techniques rather than by post-mortem examination. This may occur... 

Liu Y, Karonen JO, Vanninen RL et al. (2004) Acute ischemic stroke predictive value of 2D phase-contrast MR angiography-serial study with combined diffusion and perfusion MR imaging. Radiology 231 517-527 Lucas C, Leclerc X, Pruvo JP et al. (2000) [Vertebral artery dissections follow-up with magnetic resonance angiography and injection of gadolinium]. Rev Neurol (Paris) 156 1096-1105... 

The smallest vertebrates are homogenized whole and most laiger animals can be dissected and different tissues removed for storage in 1.5-ml Eppendorf microtubes at — 70° until homogenized. Heart, kidneys, or liver are sufficient to score more than 20 proteins testes, spleen, brain, and muscle can be sampled for tissue-specific enzymes. Additionally, blood, muscle, and/or saliva from most vertebrates can be conveniently sampled without killing the animal. During all sample preparation steps, keep tubes on crushed ice. 

Vertebral artery dissection has been described in a previously healthy man with a 3-year history of daily oral amfetamine abuse (26). 

Since this patient had no known risk factors for vertebral artery dissection and had abused amfetamine daily for 3 years with escalating amounts, an association between metamfetamine and vertebral artery dissection cannot be excluded. The local and systemic vascular impacts of amfetamine could have contributed to initial changes (along with smoking), resulting in dissection. 

Zaidat OO, Frank J. Vertebral artery dissection with amphetamine abuse. J Stroke Cerebrovasc Dis 2001 10 27-9. 

Penetrating and non-penetrating neck injuries are more likely to damage the carotid than the better protected vertebral artery. The vertebral artery appears to be more vulnerable to rotational and hyperextension injuries of the neck, particularly at the level of the atlas and axis. Laceration, dissection and intimal tears may be complicated by thrombosis and then embolism and, therefore, ischemic stroke at the time of the injury or some days or even weeks after the injury. Later stroke may be a consequence of the formation of a traumatic aneurysm, arteriovenous fistula or a fistula between the carotid and vertebral arteries (Davis and Zimmerman 1983). 

Schievink WI (2001). Spontaneous dissection of the carotid and vertebral arteries. New England Journal of Medicine 344 898-906 Schievink WI, Michels VV, Piepgras DG (1994). Neurovascular manifestations of heritable connective tissue disorders. A review. Stroke 25 889-903... 

Sturzenegger M, Matde HP, Rivoir A et al. (1993). Ultrasound findings in spontaneous extracranial vertebral artery dissection. Stroke 24 1910-1921... 

Headache is not uncommon around the time of stroke onset. It is more often severe in primary intracerebral hemorrhage than ischemic stroke, and more often severe with posterior than anterior circulation strokes. If the headache is localized at all, it tends to be over the site of the lesion. Headache is more common in cortical and posterior circulation than lacunar infarcts (Kumral et al. 1995). Severe unilateral neck, orbital or scalp pain suggests internal carotid artery dissection, particularly if there is an ipsilateral Horner s syndrome. Severe occipital headache can occur with vertebral artery dissection. Headache is also a particular feature of venous infarcts. Unusual headache in the days before stroke would suggest giant cell arteritis or perhaps a mass lesion rather than a stroke. 

Atypical antipsychotic drugs Chronic subdural hematoma (Ch. 7) Vertebral/carotid artery dissection (Ch. 6) Fat embolism (Ch. 6) nternal carotid artery stenosis (distal) Dural arteriovenous fistula (Ch. 7)... 

Until recently, catheter angiography was the standard imaging modality to confirm or exclude carotid or vertebral artery dissection (Fig. 12.2) because ultrasound was neither specific nor sensitive enough. However, there is now a widespread consensus that cross-sectional MRI, to show thrombus within the widened arterial wall, combined with MR angiography is the safest and best option. 

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