Understanding Vascular Causes of Vertigo by Dr. Abdulhussein Kareem

Vascular causes of vertigo By DR.Abdulhussein Kareem

Objectives; 1.To know the underlying cause of vertigo and to treat accordingly. 2.To differentiate between peripheral and vascular causes of acute vertigo.

Abnormalities of blood flow to the vestibular system are relatively common causes of vestibular symptoms and may be difficult to be diagnosed or distinguished from other causes. The vertigo results may be permanent due to arterial occlusion or hemorrhagic infarction or may be temporary due to arterial stenosis , vascular spasm ,or inadequate perfusion pressure. Stroke is also more common in migraine.

The blood supply to the inner ear , brainstem ,and cerebellum arises from the vertebrobasilar system. About 50% of vertebrobasilar TIA present with isolated vertigo ,which frequently lasts over an hour. Vertigo can occur from occlusion of any of the three major circumferential branches of the vertebral or basilar arteries ,AICA , PICA , and the superior cerebellar artery.

Blood flow to the inner ear is provided by the internal auditory artery which is a branch of AICA in 80% of people but in 20% ,it arises from PICA or from the basilar artery.

AICA arises constantly from the basilar art on each side at the junction of its lowest and middle thirds and passes laterally and downwards to cross the CP angle and the8th cranial nerve. At this point ,the internal auditory artery is given off ,passing almost immediately into the internal auditory meatus.

Immediately before or after crossing the 8th nerve, the main artery divides into two branches; 1.One branch passes laterally and downwards on the medial and anterior border of the cerebellar hemisphere and the send a branch which anastomoses with a cerebellar branch of the PICA.

2.Other branch which passes directly laterally and curls around the upper edge of the flocculus,where it lies on the surface of the middle cerebellar peduncle and then passes on to the cerebellar hemisphere proper and anastomoses with all the 3 cerebellar arteries. The main artery itself also supplies the pons(lateral part) and medulla oblongata(upper part).

Posterior inferior cerebellar artery (PICA); It is the largest branch of the vertebral artery ,originating from the intracranial portion of the vertebral artery 10_20 mm before the vertebrobasilar junction ,however it may arise from the basilar artery , extracranial portion of the vertebral artery , or ascending pharyngeal artery , or may be completely absent.

The PICA separates into two major trunks , the anterior and lateral trunks. It supplies the lower medulla , posteroinferior cerebellar hemisphere , and inferior vermis

Initial evaluation ; Acute vestibular syndrome(AVS) ,is the sudden (over hours or faster) onset of vertigo , nausea , vomiting , gait unsteadiness , head motion intolerance , and nystagmus . This presentation most commonly occurs with vestibular neuritis . Although most AVS is not caused by a vascular event ,it is important to quickly differentiate vertigo of vascular origin from peripheral vertigo.

The presence of neurologic features such as ataxia , dysarthria , or other neurologic signs suggests a vascular cause of AVS but the may be absent in more than half of patients. Early imaging studies such as CT and MRI scans have a low sensitivity for acute infarction. Vestibular tests(HINTS).

Vertebrobasilar insufficiency; It is a significant cause of vertigo in the elderly population which is characterized by abrupt onset , usually lasts several minutes and frequently associated with nausea and vomiting ,vertigo alone occurs in 1% of cases Other symptoms like headache , diplopia ,ataxia , numbness , weakness , or oropharyngeal dysfunction.

The underlying cause is usually atherosclerosis of the subclavian , vertebral , or basilar arteries ,due to HT or hyperlipidemia. Or due to subclavian steal syndrome. Lateral medullary syndrome (Wallenberg syndrome); It results from occlusion of the ipsilateral vertebral artery or PICA leading to infarction of the dorsolateral medulla.

Clinical features; 1. Sensory deficits affecting the trunk and extremities on the opposite side of the infarct. 2.Sensory and motor deficits affecting the face and cranial nerves in the ipsilateral side. 3.Vertigo,ipsilateral facial pain , diplopia , dysphagia , and dysphonia. Examination shows ipsilateral Horner syndrome and spontaneous nystagmus.

Hearing loss is absent because AICA is spared. Most patients with Wallenberg syndrome will have residual neurologic deficits months or years after acute infarction. Lateral pontomedullary syndrome; Infarction in the dorsolateral pontomedullary region and the inferolateral cerebellum due to lesion of the AICA .

There is combined loss of vestibular and auditory function due to involvement of the labyrinthine artery . The common initial symptoms are severe vertigo , nausea , and vomiting. Hearing loss , tinnitus , and facial paralysis. Cerebellar symptoms and nystagmus. Contralateral loss of pain and temperature sensation. Vertigo may persist for several weeks due to damage of central compensation mechanism.

MRI of AICA occlusion

MRI PICA occlusion

Cerebellar infarction ; Occlusion of the vertebral art , AICA ,PICA , or SCA may result in infarction confined to the cerebellum without brainstem involvement. Clinical features; Severe vertigo with vomiting. Ataxia . Nystagmus.

After a latent interval of 24 to 96 hours , some patients develop progressive brainstem dysfunction due to compression by a swelling cerebellum. Progression to quadriplegia , coma , and death may follow unless surgical decompression is performed.

Cerebellar hemorrhage ; Spontaneous intracerebellar hemorrhage causes neurologic symptoms that rapidly progresses to coma and death. The initial symptoms are severe vertigo , vomiting , and ataxia. Brainstem symptoms may not be present early which may lead to confusion with peripheral vestibular problem.

Diagnosis by CT scan and MRI. Treatment ; Depends on the site and size of the hematoma. It is associated with high mortality rate up to 75%.

Vertebral Artery Dissection; The symptoms of VAD are nonspecific and include dizziness , neck pain , headache , and nausea or vomiting. Dizziness is the most frequent symptom. The condition is due to a tear in the vertebral artery allowing blood to enter a false lumen in the wall of the artery and separates its layers which can lead to stenosis or dilation of the vessel.

It is more common in patient with connective tissue diseases and those who sustained neck trauma. It may result in stroke in two-thirds of patients and accounts for about 2% of cases. It may be mistaken for migraine or musculoskeletal disorders. It presents in the age of 45 and less.

Diagnosis; CT or MRI angiography; Treatment; Antiplatelet and anticoagulants. Endovascular treatment.

Cerebellar hemorrhage

Imaging; Imaging studies should be considered in patients with acute onset spontaneous vertigo ,particularly if they have vascular risk factors. The initial bedside evaluation is by HINTS which is more sensitive than CT or MRI in early hours. CT scan without contrast is the first to be done

Thin sections taken including the cerebellum, brainstem , and the 4thventricle . MRI can detect the ischemia and hemorrhage early by using DWI MRI. MRA can detect the stenosis or occlusion of the vessel

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