Vertebral Artery

• proximal portion:

  • enters the transverse foramen at C6 (88%)
  • other levels of entry occur between C3 + C7 (12%)
  • courses between longus colli + anterior scalene muscles
  • most common anomaly: origin from aortic arch --> usually enters formen of transverse process at C5/4
  • tortuosity + kinking are more common of this portion than elsewhere
  • artery can be compressed by the fascia of the scalenovertebral angle
• transverse portion:

  • courses from point of entry at spinal column to transverse foramen of C2
  • susceptible to compression by osteophytes + other degenerative changes of cervical spondylosis
  • maximum rotation + extension decrease flow
• suboccipital portion:

  • extends from exit of C2 to point of penetration of spinal canal
  • passes inferior to posterior OA membrane
• intracranial portion:

  • runs from penetration of dura mater into arachnoid space at level of foramen magnum to formation of basilar artery
• identify the structures:

  A) anterior longitudinal ligament

  B) anterior tubercle of transverse process

  C) ais

  D) vertebral body

  E) cut edge of pleura

  F) intertubercular lamella of transverse process

  G) IVD

  H) joint head of first rib

  I) lateral mass of atlas

  J) posterior tubercle of transverse process

  K) scalenus anterior

  L) transverse process of atlas

  M) ventral ramus of third cranial nerve

  N) vertebral artery

  
• tunica intima:

  • most delicate layer
  • severe trauma or plaque formation can cause tearing + separation from tunia media
  • causes rapidly flowing blood to be forced between intima + media
  • result is dissection of intima from media
• 4 regions of VA where lesions have been identified:

  • entrance of transverse foramen of C6
  • as artery passes through transverse foramen of C6-C2
  • at C1 foramen
  • as VA perforates the dura mater
• during head rotation the right, the left transverse forament moves anteriorly + slightly right when imparts a marked stretch on the left VA
• kinking + stretching of the contralateral VA can be observed with 30 deg of head rotation
• stenotic + aneurysmal lesions are most common in distal segment of the artery at level of C1 + C2
• blood flow through the carotid atery during VA occlusion increased by 1.5 times
• extracranial compression of the VA is the greatest during cervical rotation + extension; if sustained the arterial flow takes longer to return to normal
• beauty parlor stroke syndrome:

  • episode of VBA insufficiency with cerebellar infarction
  • caused by hyperextension of neck
• most common symptoms of VA dissection:

  • severe neck pain
  • brainstem or cerebellar ischemic symptoms
  • occipital headache
  • blurred vision
• types of dizziness:

  • type 1: vertigo/oscillopsia
  • type 2: presyncope
  • type 3: disequilibrium
• traumatic pathologies that may cause dizziness:

  • VA injury
  • intracranial bleeds
  • cerebral concussion
  • brainstem concussion
  • labyrinthine concussion
  • cervical joint injury
• dizziness immediately after trauma + associated with delayed pain could be caused by:

  • VA injury
  • labyrinthine concussion
  • cerebral concussion
• arterial dissection is an uncommon vascular wall condition that typically involves a tear in the artery lining + formation of an intimal flap
• clinical factors most likely to cause VA damage:

  • inadequate assessment for risk factors
  • potentially dangerous thrust technique
• a standard routine of assessment, prior to manipulating a patient would be:

  • a thorough history + subjective examination
  • cranio-vertebral or cervical scanning exam
  • specific segmental stress tests
  • pre-manipulative hold
• VBI testing:

  • extend, rotate, + side-bend head over edge of table
  • eyes remain open
  • have pt count backwards from 30 .
  • positive: diplopia, dysphagia, dysarthria, dizziness, nystagmus, + n/v
• hautard's test:

  • differentiate articular v. vascular vertigo
  • modification of rhomberg for cerebellar disease
  • pt sits on table with both arms bent to 90 deg with forearms supinated
  • pt closes eyes
  • positive: loss of position of one or both arms (tests nonvascular proprioception loss) x
• scotoma: loss of function within the visual field; common complaint of difficulty reading/watching TV + having to look from the side of the eye
• hemianopia: viual loss in half of the visual field; lesion lies at the optic chiasm
• quadranopia: visual loss in a quarter of the visual field; lesion lies posterior to the optic chiasm
• homonymous hemianopia: visual loss bilaterally right or left; results from lesion behind optic chiasm
• heteronymous field loss: loss is left + right; cuased by lesoion behin optic chiasm
• drop attacks: sudden collapses without losing consciousness
• dysphagia: difficulty swallowing; most common symptom of lateral medullary syndrome
• dysarthria: difficulty speaking
• dysphonia: horse or raspy speech
• Aniscoria: asymmetrical pupils
• ptosis: pathological depression of superior eyelid that covered part of the pupil
• jerk nystagmus: fast component (saccades) in one direction + slow recovery to midline
• nonjerk nystagmus: pendular with no fast component; equal displacement on each side of midline