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					                    CEREBRO-VASCULAR DISEASE & STROKE


BLOOD SUPPLY OF BRAIN
CEREBRO-VASCULAR DISEASE & STROKE
   Stroke is the second commonest cause of death in developed countries.
   Hypertension is the most treatable risk factor.
   Thromboembolic infarction (80%), cerebral and cerebellar haemorrhage (10%) and subarachnoid haemorrhage (about
    5%) are the major cerebrovascular problems.

DEFINITIONS
   Stroke is defined as the clinical syndrome of rapid onset of cerebral deficit (usually focal) lasting more than 24 hours or
    leading to death, with no apparent cause other than a vascular one.
   Completed stroke means the deficit has become maximal, usually within 6 hours.
   Stroke-in-evolution describes progression during the first 24 hours.
   Minor stroke. Patients recover without significant deficit, usually within a week.
   Transient ischemic attack (TIA). This means a focal deficit, such as a weak limb, aphasia or loss of vision lasting
    from a few seconds to 24 hours. There is complete recovery. The attack is usually sudden.

PATHOPHYSIOLOGY COMPLETE STROKE
One of three mechanisms is usual:
   arterial embolism from a distant site
   arterial thrombosis
   haemorrhage into the brain (intracerebral or subarachnoid).

Less commonly:
      venous infarction
      carotid or vertebral artery dissection
      polycythaemia (hyperviscosity syndromes)
      fat and air embolism
      multiple sclerosis
      mass lesions (e.g. brain tumour, abscess, subdural haematoma)
      rarities: arteritis, neurosyphilis, systemic lupus erythematosus, mitochondrial disease.

PATHOPHYSIOLOGY OF TRANSIENT ISCHEMIC ATTACK
   TIAs are usually the result of microemboli.

      Principal sources of emboli to the brain are cardiac thrombi and atheromatous plaques/thrombi within the great
       vessels, and carotid and vertebral systems.

PATHOPHYSIOLOGY OF TRANSIENT ISCHEMIC ATTACK
   TIAs are usually the result of microemboli.

      Principal sources of emboli to the brain are cardiac thrombi and atheromatous plaques/thrombi within the great
       vessels, and carotid and vertebral systems.

RISK FACTORS & PREVENTION
    Treatment of hypertension (of vital importance)
    Cessation of smoking; 50% reduction within 1 year reaching normal risk after 5 years
    Active lifestyle
    Moderate alcohol consumption
    Statin therapy
    Anticoagulation in atrial fibrillation
    Weight reduction in obesity
    Treating polycythaemia
    Surgery for carotid stenosis
 RISK FACTORS OF CEREBRAL HAEMORRHAGEa
      Hypertension
     Bleeding disorders
     Pre-existing cerebral aneurysm
     Anticoagulant and antiplatelet drug therapy

 TRANSIENT ISCHEMIC ATTACKS (TIAs)
 Symptoms:
   TIAs cause sudden loss of function, usually within seconds, and last for minutes or hours (but by definition <24 hours).
       The site is often suggested by the type of attack.


                             TRANSIENT ISCHEMIC ATTACKS (TIAs)
                            Features of transient ischemic attacks
                        Anterior circulation          Posterior circulation
                        Carotid system                   Vertebrobasilar system
                        Amaurosis fugax                   Diplopia, vertigo, vomiting
                        Aphasia                           Choking and dysarthria
                        Hemiparesis                       Ataxia
                        Hemisensory loss                  Hemisensory loss
                        Hemianopic visual loss            Hemianopic visual loss
                                                          Transient global amnesia
                                                          Tetraparesis
                                                          Loss of consciousness (rare)

Clinical findings in TIA
      It is unusual to witness an attack.
      Consciousness is usually preserved in TIA.
      There may be clinical evidence of a source of embolus, such as: carotid arterial bruit (stenosis), atrial fibrillation or
       other dysrhythmia, valvular heart disease/endocarditis, recent myocardial infarction or difference between right
       and left brachial BP.

Un underlying condition may be evident
atheroma
hypertension
postural hypotension
bradycardia or low cardiac output
diabetes mellitus
rarely, arteritis, polycythaemia
antiphospholipid syndrome

Differential diagnosis
Mass lesion
Focal epilepsy
A focal prodrome of migraine
Prognosis: Prospective studies show that 5 years after a single thromboembolic TIA:
30% have had a stroke, a third in the first year
15% have suffered a myocardial infarct.
TIA in the anterior cerebral circulation carries a more serious prognosis than one in the posterior circulation
  TYPICAL STROKE SYNDROMES Cerebral infarction
  Clinical features:
        The most common stroke is caused by infarction in the internal capsule following thromboembolism in a middle
         cerebral artery branch. A similar picture is caused by internal carotid occlusion.
        Limb weakness on the opposite side to the infarct develops over seconds, minutes or hours.
        There is a contralateral hemiplegia or hemiparesis with facial weakness.
        Aphasia is usual when the dominant hemisphere is affected.
        Weak limbs are at first flaccid and areflexic.
        Headache is unusual. Consciousness is usually preserved.
        After a variable interval, usually several days, reflexes return, becoming exaggerated. An extensor plantar response
         appears.


                               BRAIN STEM INFARCTION

              CLINICAL PICTURE                      STRUCTURE INVOLVED
              Hemiparesis or tetraparesis          Corticospinal tracts
              Sensory loss                         Medial lemniscus and spinothalamic tracts
              Diplopia                              Oculomotor system
              Facial numbness                      Fifth nerve nuclei
              Facial weakness (LMN)                Seventh nerve nucleus
              Nystagmus, vertigo                   Vestibular connections
              Dysphagia, dysarthria                Ninth and tenth nerve nuclei
              Dysarthria, ataxia, hiccups          Brainstem and cerebellar connections
              Horner's syndrome                    Sympathetic fibres
              Altered consciousness                Reticular formation

              This causes complex signs depending on the relationship of the infarct to cranial nerve nuclei,
              long tracts and brainstem connections

The lateral medullary syndrome
      The lateral medullary syndrome, also called posterior inferior cerebellar artery (PICA) thrombosis, or Wallenberg's
       syndrome, is a common example of brain-stem infarction presenting as acute vertigo with cerebellar and other
       signs. It follows thrombo-embolism in the PICA or its branches, vertebral artery thrombo-embolism or dissection.
       The clinical picture depends on the precise structure damaged.

Clinical picture of PICA occlusion
Ipsilateral
Facial numbness 5th
Diplopia 6th
Nystagmus
Ataxia (cerebellar)
Horner’s syndrome
9th and 10th nerve lesion
Contralateral
Spinothalamic sensory loss
Hemiplegia (mild, unusual)

Lacunar infarction
Lacunes are small (<1.5 cm3) infarcts seen on MRI or at autopsy. Hypertension is commonly present. Minor strokes (e.g.
pure motor stroke, pure sensory stroke, sudden unilateral ataxia and sudden dysarthria with a clumsy hand) are
syndromes caused typically by single lacunar infarcts. Lacunar infarction is also often symptomless.

Hypertensive encephalopathy
This describes the neurological sequelae of malignant hypertension. Severe headaches, TIA, stroke, and rarely
subarachnoid haemorrhage occur. Papilloedema may develop, either as part of an ischaemic optic neuropathy or
following brain swelling due to multiple acute infarcts.
Multi-infarct dementia (vascular dementia)
      Multiple lacunes or larger infarcts cause generalized intellectual loss seen with advanced cerebrovascular disease.
       The condition tends to occur with a stepwise progression over months or years with each subsequent infarct.
       There is eventually dementia, pseudobulbar palsy and a shuffling gait with small steps (parkinsonism). Binswanger's
       disease is an imaging term describing low attenuation in cerebral white matter, with dementia, TIAs and stroke
       episodes in hypertensive patients.

Acute stroke: immediate care, and thrombolysis
       Paramedics and members of the public are encouraged to make the diagnosis of stroke on a simple history and
        examination
       – FAST:
■ Face – sudden weakness of the face
■ Arm – sudden weakness of one or both arms
■ Speech – difficulty speaking, slurred speech
■ Time – the sooner treatment can be started, the better.
       Dedicated units with multidisciplinary, organized teams deliver higher standards of care than a general hospital
        ward

Investigations
The purpose of investigations in both stroke and
TIA is:
       to confirm clinical diagnosis
       to distinguish between haemorrhage and thromboembolic infarction
       to look for underlying causes of disease and to direct therapy, either medical or surgical

Imaging TIA & stroke patients
     Imaging TIA and stroke patients CT and MRI. CT imaging will demonstrate haemorrhage immediately while a
      patient with an infarct may have a normal scan. Infarctions are usually detectable at 1 weeK although 50% are
      never detected on CT. CT or MRI should be carried out urgently in the majority of cases. Diffusion-weighted
      imaging (DWI) MR can identify infarcted areas within a few minutes of onset. Conventional T2 weighting is no
      better than CT. Imaging will also show the unexpected, e.g. subdural haematoma, tumour or abscess.

Further investigations
     Routine bloods (for polycythaemia, infection, vasculitis, thrombophilia, syphilitic serology, clotting studies,
      autoantibodies, lipids)
     Chest X-ray
     ECG
     Carotid Dopplers
     Angiography

Management of cerebral infarction
    The possible sources of embolus should be sought (e.g. carotid bruit, atrial fibrillation, valve lesion, evidence of
     endocarditis, previous emboli or TIA)
    Assess hypertension and postural hypotension
    The brachial blood pressure should be measured in each arm; a difference of more than 20 mmHg is suggestive of
     subclavian artery stenosis.
    The neurological deficit should be carefully documented.
Immediate management
    Admit to multidisciplinary hospital stroke unit if possible.
    General medical measures
    Care of the unconscious patient, Oxygen by mask, Assessment of swallowing, Check BP and look for source of
     emboli.
    Immediate brain imaging is essential.
    Cerebral infarction : If CT shows infarction, give aspirin (300 mg/day initially) antiplatelet therapy if no
     contraindications, give alteplase thrombolysis, which must be started within 3 hours (aim for 90 min) of stroke;
     informed consent is essential.
    Cerebral haemorrhage: If CT shows haemorrhage, do not give any therapy that may interfere with clotting.
     Neurosurgery may be required.

Further management
     Appropriate drugs for hypertension, heart disease, diabetes, other medical conditions
     Other antiplatelet agents, e.g. dipyridamole
     Question of endarterectomy
     Question of anticoagulation
     Speech therapy, dysphagia care, physiotherapy, occupational therapy
     Specific neurological issues, e.g. epilepsy, pain, incontinence
     Preparations for future care

Long term management
Medical management
     Treatment of all risk factors
     Antihypertensive treatment
     Antiplatelets: Combined aspirin 75 mg daily and dipyridamole 200 mg twice daily is probably the best prophylaxis
      against further thromboembolic stroke or TIA.
     Anticoagulants: in AF, prosthetic valves, cardiomyopathy

Surgical treatment
      Internal carotid endarterectomy: Surgery is recommended in TIA or stroke patients shown to have internal carotid
       artery stenosis greater than 70%. Successful surgery reduces the risk of further TIA/stroke by approximately 75%.
       Endarterectomy has a mortality around 3%, and a similar risk of stroke.
      Percutaneous transluminal angioplasty (stenting) is an alternative procedure.

Rehabilitation (speech therapy & physiotherapy)
     Skilled physiotherapy in the first few weeks after stroke, relieves spasticity, prevents contractures and teaches
      patients to use walking aids.
     In aphasia: It is possible that spontaneous return of speech is hastened as much by normal conversation with a
      relative as by a therapist.
     If the patient cannot swallow safely without the risk of aspiration, either nasogastric feeding or percutaneous
      gastrostomy will be needed.

Prognosis
     Twenty-five per cent of patients die within 2 years of a stroke. Around 30% of this group die in the first month
     Gradual improvement usually follows stroke, although the late residual deficit may be severe. Of those who
      survive, about one-third return to independent mobility and one-third have serious disability requiring permanent
      institutional care.

Intracerebral hemorrhage
This comprises:
      intracerebral and cerebellar haemorrhage
      subarachnoid haemorrhage
      subdural and extradural haemorrhage/haematoma.
Etiology
      Intracerebral haemorrhage causes around 10% of strokes.
      Haemorrhage is usually massive, often fatal and occurs in chronic hypertension and at well-defined sites - basal
       ganglia, pons, cerebellum and subcortical white matter.

Recognition
     At the bedside, there is no entirely reliable way of distinguishing between intracerebral haemorrhage and
      thromboembolic infarction. Both produce stroke. Intracerebral haemorrhage, however, tends to be dramatic with
      severe headache. It is more likely to lead to coma than thromboembolic stroke.
     Brain haemorrhage is seen on CT imaging immediately - as intracerebral, intraventricular, or subarachnoid blood.
      MR imaging may not identify an acute haemorrhage correctly in the first few hours. Thereafter T2 weighted MR is
      very reliable.

Managing hemorrhagic stroke
    The principles are those for cerebral infarction. The immediate prognosis is less good.
    Antiplatelet drugs and, of course, anticoagulants are contraindicated.
    Control of hypertension is vital.
    Urgent neurosurgical clot evacuation is sometimes considered when there is deepening coma and coning
     (particularly in cerebellar haemorrhage).
    The outlook is usually poor.

Cerebellar hemorrhage
     There is headache and rapid reduction of consciousness with signs of brainstem origin (e.g. nystagmus, ocular
      palsies).
     Gaze deviates towards the haemorrhage.
     There are unilateral or bilateral cerebellar signs, if the patient is awake.
     Cerebellar haemorrhage sometimes causes acute hydrocephalus. Emergency surgical clot evacuation is often
      necessary after imaging.

Subarachnoid hemorrhage (SAH)
Causes
      Saccular aneurysms
      Arteriovenous malformation (AVM)
      No lesion found
      Rare associations: bleeding disorders, mycotic aneurysms

Clinical picture of SAH
      There is a sudden devastating headache, often occipital. This is usually
       followed by vomiting and often by coma.
      The patient remains comatose or drowsy for several hours to several days,
        or longer.
      After major SAH there is neck stiffness and a positive Kernig's sign.        Internal carotid artery aneurysm
      Papilloedema is sometimes present.
      Minor bleeds cause few signs, but almost invariably headache.
Investigations
      CT imaging is the initial investigation of choice. Subarachnoid or
       intraventricular blood is usually seen.
      Lumbar puncture is not necessary if SAH is confirmed by CT, but
       should be performed if doubt remains. The CSF becomes yellow
       (xanthochromic) several hours after SAH. Visual inspection of the
       supernatant CSF is usually sufficiently reliable for diagnosis, but there
       is a move to use spectrophotometry to estimate bilirubin released from
       lysed cells to define with certainty SAH in doubtful cases.
      MR angiography is usually performed in all potentially fit for surgery,
       i.e. generally below 65 years and not in coma. In some cases, no
       aneurysm is found despite a definite SAH.


Complications                                                                              A-V malformation
    Blood in the subarachnoid space can lead to obstruction of CSF flow and hydrocephalus. This can be
     asymptomatic but may cause deteriorating consciousness after SAH. Diagnosis is by CT. Shunting may be
     required.
    Severe arterial spasm (visible on cerebral angiography and a cause of coma or stroke) sometimes complicates SAH.
     It is a poor prognostic sign.

Management
    Immediate treatment of SAH is bed rest and supportive measures.
    Hypertension should be controlled.
    Dexamethasone to reduce cerebral oedema and to stabilize the blood-brain barrier.
    Nimodipine, a calcium-channel blocking agent, reduces mortality.
    When angiography demonstrates aneurysm, a direct neurosurgical approach to clip the neck of the aneurysm is
     carried out.
    Invasive radiological techniques, such as inserting a fine wire coil into an aneurysm are also used.
    Direct surgery, microembolism and focal radiotherapy ('gamma knife') are used in AVM.

Subdural hematoma
     SDH means accumulation of blood in the subdural space following rupture of a vein. It usually follows a head
      injury, which may be trivial. The interval between injury and symptoms may be days, weeks or months. Chronic,
      unsuspected or spontaneous SDH is common in the elderly and in alcohol abuse.
     Headache, drowsiness and confusion are common; symptoms are indolent and often fluctuate. Focal deficits such
      as hemiparesis or sensory loss develop. Epilepsy occasionally occurs. Stupor, coma and coning may follow, but
      there is a tendency for SDH to resolve spontaneously.

Extradural hemorrhage
     This follows a linear skull vault fracture tearing a branch of the middle meningeal artery. Blood accumulates
      rapidly over minutes/hours in the extradural space. The most characteristic picture is of a head injury with a brief
      duration of unconsciousness followed by a lucid interval of recovery. The patient then develops a progressive
      hemiparesis and stupor, and rapid transtentorial coning, with first an ipsilateral dilated pupil, followed by bilateral
      fixed dilated pupils, tetraplegia and respiratory arrest.
     An acute subdural haemorrhage presents in a similar way.

Management
    Suspected extradural or subdural haemorrhage needs immediate imaging.
    Extradural bleeding requires urgent neurosurgery. If performed early, the
      outlook is excellent.
    Subdural bleeding may allow; more conservative management - even
     large subdural collections can resolve.
     Progress is assessed with serial imaging, but close liaison with a
     neurosurgeon remains essential.

				
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