Vertebrobasilar insufficiency: Difference between revisions
No edit summary |
|||
Line 10: | Line 10: | ||
===Subclavian Steal phenomenon=== | ===[[Subclavian Steal]] phenomenon=== | ||
A stenotic lesion in the subclavian, located proximal to the vertebral artery, results in reversing the flow of blood in the vertebral artery when superimposed with increased arm activity(4). | A stenotic lesion in the subclavian, located proximal to the vertebral artery, results in reversing the flow of blood in the vertebral artery when superimposed with increased arm activity(4). | ||
Revision as of 22:04, 13 February 2016
Background
Vertebrobasilar insufficiency (VBI) is characterized by diminished bloodflow through the vertebral or basilar arteries. The two vertebral arteries originally branch proximally from the subcalvian artery and travel through the vertebrae and distally join to become the basilar artery. Symptoms result from diminished circulation to the posterior brain, brainstem and cerebellum. Head-turning can cause ipsilateral vertebral artery to temporarily occlude; if the contralateral vertebral artery is stenotic, this may lead to syncope. This is also known as Bow hunter's Syndrome[1]
- Head extension may also provoke symptoms. Neurologic symptoms tend to not present when one vertebral artery remains patent[2]
- Symptoms may result secondary to arterial plaques, arterial dissection, compressive lesions, or subclavian steal (see below). Posterior strokes encompass 20-30% of all strokes[3]
- Cervical ostephytes can also directly compress vertebral arteries and cause VBI symptoms[4].
Bow hunter's syndrome (Rotational vertebral artery compression)
- Head turning causes temporary occlusion of the ipsilateral vertebral artery. VBI results if the contralateral vertebral artery has a fixed occlusion[5]. Improvement of symptoms in neutral position is considered pathognomonic[6]
Subclavian Steal phenomenon
A stenotic lesion in the subclavian, located proximal to the vertebral artery, results in reversing the flow of blood in the vertebral artery when superimposed with increased arm activity(4).
Clinical Features
Symptoms
- Numbness/tingling
- Vertigo/dizziness
- Changes in vision
- Nausea/vomiting
- Weakness
- Dysphagia
- Dysarthria
- Syncope
Differential Diagnosis
Vertigo
- Vestibular/otologic
- Benign paroxysmal positional vertigo (BPPV)
- Traumatic (following head injury)
- Infection
- Ménière's disease
- Ear foreign body
- Otic barotrauma
- Otosclerosis
- Neurologic
- Cerebellar stroke
- Vertebrobasilar insufficiency
- Lateral Wallenberg syndrome
- Anterior inferior cerebellar artery syndrome
- Neoplastic: cerebellopontine angle tumors
- Basal ganglion diseases
- Vertebral Artery Dissection
- Multiple sclerosis
- Infections: neurosyphilis, tuberculosis
- Epilepsy
- Migraine (basilar)
- Other
- Hematologic: anemia, polycythemia, hyperviscosity syndrome
- Toxic
- Chronic renal failure
- Metabolic
Diagnosis
Work-up
- Glucose check
- Full neuro exam
- TM exam
- CTA or MRA (diagnostic study of choice) of the neck/brain if symptoms consistent with central cause
Test | Sensitivity |
HINTS | 100% |
MRI (24hrs) | 68.40%[7] |
MRI (48hrs) | 81%[7] |
CT non con | 26%[8] |
HINTS Exam
Proposed as method of distinguishing peripheral cause from cerebellar/brain stem CVA in the Emergency Department population [9][10][11]
Inclusion Criteria
- HINTS exam should only be used in patient with acute persistent vertigo, nystagmus, and a normal neurological exam.
- HINTS exam, when done correctly, has high sensitivity and specificity in distinguishing peripheral vs central etiologies of vertigo
- Note that the original study was done by neuro-ophthalmologists in a differentiated patient base. This exam has not been studied in a large ED population yet
The 3 components of the HINTS exam include:
HINTS Test | Reassuring Finding |
Head Impulse Test | Abnormal (corrective saccade) |
Nystagmus | Unidirectional, horizontal |
Test of Skew | No skew deviation |
- Always use correct terminology; "HINTS negative" does not convey a clear interpretation. State "HINTS central" or "HINTS peripheral" as suggested in literature
- If able, specify the exact exam finding as shown by chart above
Head Impulse Test
Test of vestibulo-ocular reflex function
- Have patient fix their eyes on your nose
- Move their head rapidly in the horizontal plane to the left and right
- When the head is turned towards the normal side, the vestibular ocular reflex remains intact and eyes continue to fixate on the visual target
- When the head is turned towards the affected side, the vestibular ocular reflex fails and the eyes make a visible corrective saccade to re-fixate on the visual target [12][13]
- Normally, a functional vestibular system will identify any movement of the head position and instantaneously correct eye movement accordingly so that the center of the vision remains on a target.
- This reflex fails in peripheral causes of vertigo affecting the vestibulocochlear nerve unilaterally; thus, failure of the reflex unilaterally is reassuring (since the cause is peripheral)
- Note that in central causes of vertigo, test may show normal reflex response OR failure of the reflex BILATERALLY
Nystagmus
- Observation for nystagmus in primary, right, and left gaze
- No nystagmus (normal) or only horizontal unilateral nystagmus (fast direction only in one direction) is reassuring
- Any other type of nystagmus is abnormal, including vertical or bidirectional nystagmus
Test of Skew
- Have patient look at your nose with their eyes and then cover one eye
- Then rapidly uncover the eye and quickly look to see if the eye moves to re-align.
- Repeat with on each eye
- Skew deviation is a fairly specific predictor of brainstem involvement in patients with acute vestibular syndrome. The presence of skew may help identify stroke when a positive head impulse test falsely suggests a peripheral lesion.
- Skew is also known vertical dysconjugate gaze and is a sign of a central lesion
- A positive HINTS exam: 100% sensitive and 96% specific for the presence of a central lesion.
- The HINTS exam was more sensitive than general neurological signs: 100% versus 51%.
- The sensitivity of early MRI with DWI for lateral medullary or pontine stroke was lower than that of the HINTS examination (72% versus 100%, P=0.004) with comparable specificity (100% versus 96%, P=1.0).
- If any of the above 3 tests are consistent w/ CVA obtain full work-up (including MRI)
Management
Medical management
- Lower cholesterol
- Control hypertension
- Smoking cessation
- Antiplatelets
Surgical management
- Endarterectomy
- Bypass grafting
- Stenting
Disposition
- Admit
See Also
External Links
References
- ↑ # Go G, Hwang S-H, Park IS, Park H. Rotational Vertebral Artery Compression : Bow Hunter’s Syndrome. Journal of Korean Neurosurgical Society. 2013;54(3):243-245. doi:10.3340/jkns.2013.54.3.243.
- ↑ Ibrahim Alnaami, Muzaffer Siddiqui, and Maher Saqqur, “The Diagnosis of Vertebrobasilar Insufficiency Using Transcranial Doppler Ultrasound,” Case Reports in Medicine, vol. 2012, Article ID 894913, 3 pages, 2012. doi:10.1155/2012/894913.
- ↑ Ibrahim Alnaami, Muzaffer Siddiqui, and Maher Saqqur, “The Diagnosis of Vertebrobasilar Insufficiency Using Transcranial Doppler Ultrasound,” Case Reports in Medicine, vol. 2012, Article ID 894913, 3 pages, 2012. doi:10.1155/2012/894913.
- ↑ Tintinalli
- ↑ # Go G, Hwang S-H, Park IS, Park H. Rotational Vertebral Artery Compression : Bow Hunter’s Syndrome. Journal of Korean Neurosurgical Society. 2013;54(3):243-245. doi:10.3340/jkns.2013.54.3.243.
- ↑ # Go G, Hwang S-H, Park IS, Park H. Rotational Vertebral Artery Compression : Bow Hunter’s Syndrome. Journal of Korean Neurosurgical Society. 2013;54(3):243-245. doi:10.3340/jkns.2013.54.3.243.
- ↑ 7.0 7.1 http://www.cnsuwo.ca/ebn/downloads/cats/2010/CNS-EBN_cat-document_2010-07-JUL-30_a-negative-dwi-mri-within-48-hours-of-stroke-symptoms-ruled-out-anterior-circulation-stroke_4494E.pdf
- ↑ Chalela JA, Kidwell CS, Nentwich LM, et al. Magnetic resonance imaging and computed tomography in emergency assessment of patients with suspected acute stroke: a prospective comparison. Lancet. 2007;369:293–8.
- ↑ http://ec.libsyn.com/p/a/d/d/add761f2a2847ea5/hints-exam.pdf?d13a76d516d9dec20c3d276ce028ed5089ab1ce3dae902ea1d01c0873ed8cc5fe910&c_id=2502227
- ↑ http://www.ncbi.nlm.nih.gov/pubmed/18541870
- ↑ http://hwcdn.libsyn.com/p/1/c/d/1cd6b38a89c178a1/diff-of-vertigo.pdf?c_id=2502226&expiration=1380995436&hwt=0a8bc67ea910e018a1543ebea192f668
- ↑ Barraclough K, Bronstein A. Vertigo. BMJ. 2009;339:b3493
- ↑ Kuo CH, Pang L, Chang R. Vertigo - part 1 - assessment in general practice. Aust Fam Physician. 2008;37(5):341-7