Showing posts with label Cerebral Vasospasm. Show all posts
Showing posts with label Cerebral Vasospasm. Show all posts

Sunday, April 22, 2012

Management of Status Epilepticus (PART 2)

MANAGEMENT OF TONIC- CLONIC  SE:(1,2)
Time from initiation
of observation and
treatment (min)          Procedure
=================================================
        0                         Assesss cardiorespiratory function
                                   as the presence of tonic clonic sta
                                   tus is verified.If ensure of diagnosis
                                   observe one tonic-clonic attack and
                                   verify the presence of unconcious
                                   ness after the end of the tonic clo
                                   nic attack.Insert oral airway and ad
                                   minister 02,if necessary.Insert an in
                                   travenous catheter.Draw venous 
                                   blood to determine anticonvulsant
                                   levels,glucose,BUN,electrolytes,and
                                   complete blood count stat.Draw ar
                                   terial blood for stat pH,PO2,PCO2,
                                   HCO3-.Monitor respiration,blood 
                                   pressure,and electrocardiograph.
                                   If possible monitor encephalograph.


        5                         Start iv infusion with NS contain- 
                                   ing with B complex. Give a bolus    
                                   injection of 50 ml of 50% glucose.


     10                          Infuse 1 mg lorazepam over 5 mi  
                                  nutes also give fosphenytoin to a
                                  total of 17 mg/kg(level >20 mcg
                                  per ml). If hypotension develops
                                  slow infusion rate.Phenytoin 50
                                  mg/ml in propyleneglycol may be
                                  placed in a 100 ml volume control
                                  set and diluted with normal saline.     
                                  the rate of infusion should be 
                                  watched. Alternatively phenytoin  
                                  may be injected slowly by iv.


    20                         If seizures persist give 1mg lorazepam 
                                 intravenously.


    30                         If seizures persist consider pseudo 
                                seizures if no CNS infection or   
                                trauma.Otherwise, phenobarbital 20 
                                mg/kg iv no faster than 100 mg/min  
                                until seizures stop or to a loading of 20 
                                mg/kg(level > 40 mcg/ml).


  60                          If seizure continue, general anesthesia  
                               with pentobarbital is instituted.


120                          If SE continue a neurologist and 
                               anesthesiologist with expertise in SE    
                               should be consulted. Advice from a 
                               regional epilepsy center on the 
                               management of intractable SE also 
                               should be sought Push pentobarbital      
                               until seizures stop or hypotension 
                               arises.With cessation of seizures if
                               still twitching assess EEG to rule out
                               subtle SE.


Generalized convulsive SE is considered a neurologic emergency.
Treatment to secure the airway, provide oxygen,and maintain circulation must be initiated within the first fiew minutes to prevent complications such as hypoxaemia,
systemic hypertension,tachydysrythmia.


Protocols for the treatment of convulsive SE remain somewhat individualized by institution and specialty.
Recent trends have pushed aggressive treatment beginning as soon as 10 minutes into continuous convulsive state. 
In practice this intervention can rarely be effected except in hospital. One of many approaches to control SE is shown as mention above. 
This protocol reflects the current widespread use of lorazepam titrated to effect (0,03 to 0,22 mg/kg) as a subtitute for diazepam.
Parke Davis has withdrawn phenytoin(Dilantin) in favor of the prodrug fosphenytoin(Cerebyx).This a water soluble preparation with pH of 9 is converted in 15 minutes to the active drug phenytoin by tissue phosphatases. It is equally as effective as phenytoin but without complications of the propyleneglycol solvent and higher alkalinity (pH 12).
It can be delivered intramuscularly and more stable in the iv form but it can also precipitate hypotension if adminis-
tered too rapidly.


Phenobarbital as alternative drug when seizure persist after lorazepam. Physicians are using thiopental much earlier in the treatment of SE when phenobarbital is not available.
When phenytoin and phenobarbital are ineffective, a benzodiazepine is often suggested. Midazolam and diazepam have a shorter onset time than lorazepam although lorazepam generally has a longer duration of action with a lower likelihood of severe respiratory depression making it the preferred agent of some clinicians.


Diazepam is the fastest onzet (1-3 minutes) and hystoricaly was the treatment of choice because is known as the fastest  medication to terminate seizures. However because of its lipholicity diazepam has a very short duration in CNS (10-20 min). For this reason lorazepam has replaced diazepam as the drug of choice. Its onset in only slower (2-3 min) but its anticonvulsant action typically last for more than 4 hours.
Diazepam has been reported to be effective rectally, and midazolam to be effective intramuscularly and intranasally in children.
If seizures continue to be refractory to treatment with the previously noted drugs, pentobarbital  usually can be used some times thiopental.


Alternatively,volatile anesthetics can also be used. 
Intravenous valproate (depakene) is now available which being tried in refractory status. Any of the other non iv formulated AEDs can be administered via nasogastric tube.
Propofol has been used in ambulances for patient refractory to iv benzodiazepine, given in 30 mg boluses every 30 seconds until the seizure are terminated.There may be a future role for alpha 2 agonist therapy as such drugs become clinically available. 
Dexmedetomidine confered brain protection in an animal
seizure model.


Other protocol for tonic clonic generalized SE based on stage :


Stage             General measures            AEDs  Usual route of adm
Premonitory   Continued neurolo           Diazepam 10mg iv bolus                                                                
                     gic observation,dia         max 5mg/min
                     agnostic SE by ob           Lorazepam 4mg iv bolus                                       
                     serving continued           max 2mg/min                                                    
                     seizure activity of          Midazolam 5mg iv bolus                                                                                               
                     one additional sei           max 4m/min 
                     zure.                             Paraldehyde 5- 10 ml in
                                                         5- 1 ml water or oil
                                                         by rectal First line


Early              Ensure adequate           Diazepam 10mg iv bls
(0-30 mins)     cardiorespiratory          Lorazepam 4- 8mg iv
                     function,iv line,ad-             
                     minister 02,initiate      Second line
                     regular ECG,and BP      Midazolam  5-10 mg iv
                     monitoring,draw         Phenytoin 15-18 mg/kg
                     blood for emergen-     iv loading                  
                     cy investigations,in-    dose(max.               
                     tubation may be          50mg/min.
                     considered.                Paraldehyde solution 4%                                        
                                                      in saline,50-100ml/h                                                                                  
                                                      iv solution
                                                      Lidocaine:iv bolus and
                                                      short infusion.


Established     Set second iv line         First line                 
                     (large veins)admi-        Phenytoin repeate                        
                     nister thiamine 100       7mg /kg iv.                                
                     mg iv and glucose         Phenobarbital                                    
                     D50W-50 ml iv,           10-20 mg/kg iv         
                     treat acidosis,estab      loading dose                                         
                     lished etiology,admis-  (<100mg/m)
                     sion to ICU,intubation   second line        
                     ICU,intubation has to    Diazepam iv infusion       
                     be considered,EEG/     Midazolam iv infusion
                     ECG monitoring.          Paradeldehyde iv infusion


Refractory   Full anesthesia needed    First line
(>120 min)   EEG/ECG monitoring,ar-  Pentobarbital iv/infus
                   terial line,initiate pres-   Propofol iv/infusion           
                   sor therapy when requi-        
                   red monitoring of AEDs    Second line
                   levels intracranial pres-    Isoflurane inhalation      
                   sure monitoring where 
                   appropriate.


In a patient who is actively seizing a lateral position may help prevent aspiration.The choice of iv fluids should include normal saline if phenytoin will be used because phenytoin will precipitate in glucose containing solution 


After 8 mg of lorazepam if seizures have not been aborted
use of another anticonvulsant medication is indicated.
If benzodizepine are effecive in seizure control further seizures need to be prevented with a long acting anticonvulsant.


A loading dose of phenytoin is 18-20 mg /kg ,even at the recomended rate of administration (50mg/min),hypotension is the most common side effect and mandates decreasing the infusion rate.


to be continued

Monday, February 27, 2012

Cerebral Vasopasm (PART 2)

TREATMENT :


Pharmacologic treatment:(1,4)


Numerous drugs have been investigated for prevention or treatment vasospasm but most are ineffective.


Calcium channel blockers (calcium antagonist) which nimodipine has been more extensively studied are the only drugs that have been shown to consistently reduce the mortality and morbidity from vasospasm in all patients with SAH irrespective of the grades. 


Nimodipine, a dehydropyridine calcium antagonist blocks the intracellular influx of extra cellular calcium, preventing arterial smooth muscle contraction. It was initially believed that this agent prevents constriction of vessels; however clinical trial have shown no change in the incidence or severity of angiographic vasospasm.


It is now postulated that improved outcome is related either to decrease in vasospasm in the microvasculature which is not visualized by angiography or to a modification of calcium influx into the damage cells which limited the extent of neural injury.


Interestingly none of these favourable studies with calcium antagonist prophylaxy was able to demonstrate any signifi
signicant change in the incidence or severity of vasospasm.


Nicardipine is another dehydropyridine calcium antagonist in high dose intravenous has been investigated for prevention of vasospasm.


Nicardipine studied in SAH therapy continuous iv infusion for 14 days after SAH has shown to decrease the incidence of vasospasm but compared with placebo,nicardipine has not shown to improve clinical of vasospasm outcome at 3 months.


Nimodipine,60 mg every 4 hours should be used enterally as soon after the ictus as possible ;preferably before 96 hrs.


It is continued for 14 to 21 days 


Hypotension is seen in about 5% of patients treated with enteral nimodipine and in 28% to 33% of patients treated iv nicardipine.


Therefore the BP should be monitored carefully;the hypo
tension is typically readily treatable with fluid adminstra 
tion.Pulmonary oedema,presumably as manifestation of high output congestive heart failure(CHF) has also been associated with dehydropyridine therapy.


An early clinical trial of tirilazad mesylate,a potent lipid peroxidation inhibitor in Europe,Australia and New Zealand demonstrated that at 6 mg per kg per day,a significant reduction in symptomatic vasospasm occured primarily
primarily in men.However a subsequent trial in North America involving 897 patients failed to demonstrate any improvement over placebo.


A subsequent trial with a higher dose(15mg/kg per day) in women demonstrated a slight improvement in mortality in patients with poor neurologic grade but no difference from the placebo group when all patients were considered.


Approaching from another direction,a clinical trial with a hydroxyl radical scavenger (nicaraven) reported a 35% reduction of the incidence of delayed ischemic deficit.


These result although promising,await confirmation with a larger clinical trial.


In retrospective study,patients taking aspirin before their SAH had reduced risk of delayed ischemic deficit and there
fore the use of aspirin post aneurysm clipping require further study.


 HYPERVOLEMIC,HYPERTENSIVE AND HEMODILUTION
 (TRIPLE H)(1,2)
 The rationale behind induced hypervolemia and hyper
 tension is that in SAH the ischemic area of the brain have 
 impaired autoregulation and thus CBF depends on the  
 intravascular volume and mean arterial pressure(MAP).

The aims of triple H therapy is to optimize cerebral 
 perfusion by increasing CBF and improving flow 
 characteristics by haemodilution.

Hypervolemia is achieved by the administration of some 
 combination of colloids,crystalloids and blood products.
 Colloid may at times be superior to crystalloid solution in 
 maintaining hypervolemia.

This therapy is most successful if instituted early when the 
 neurologic deficit are mild and before the onset of 
 infarction.However prophylactic treatment initiated before aneurysm clipping,is associated with a significant risk of rebleeding(19% in one series).


Other concerns include worsening of cerebra oedema,
increasing ICP,and causing hemorrhage into an infarcted area.Other systemic complications included pulmonary oedema(7% to 17%),myocardial infarction(2%),dilutional hyponatremia(3% t0 35%),and cogulopathy(3%).


To optimized theraphy and minimize the potential cardio
vascular and pulmonary complication,invasive monitors including direct arterial pressure,CVP or preferably a pulmonary artery catheter are essential.


Sufficient iv fluids are infused to increase the CVP to 10 mmHg or the pulmonary artery wedged pressure (PAWP) t0 12 to 20 mmHg.


In recent study where a starling curve was constructed in nine patients with a ruptured aneurysm ,Levy and Giannotta observed the increasing the PAWP from 8 to 14 mmHg correlated with significant increases in left ventricular stroked work  index,stroke volume index,and cardiac index.


However further volume expansion to increase PAWP to above 14 mmHg resulted in  a decline in the cardiac index.


The initial step is to increase cardiac output and BP with agressive volume expansion.In addition to maintanance fluids of 2-3 litres per day,colloids or packed red cell are used to obtain the following:
             -Hematocriet of 30-35%
             -PAWP of  8-14 mmHg
             -Cardiac Index(CI) of 4,5L/m2/min
             -Systemic vascular resistance(SVR) index of 1400-
              2000 dyne/sec/cm3.
             -SBP of 120 -150 mmHg in unclipped and 160-200 
              mmHg in clipped aneurysm.
 Although iv fluid alone is often effective is at times 
 insufficient to raise BP or reverse the ischemic symptoms;
 vasopressors are then initiated to induce hypertension .

The most widely used vasopressors are dopamine,dobu-
 tamine,nor adrenaline or phenylephrine.

If after volume expansion the above parameters cannot be achieved or there are no improvement in neurologic status
inotropes(usually dopamine 2,5-15 mcg/kg/min)are started.


The use of appropriate inotropes/vasopressors is guided by a pulmonary artery catheter.


In some cases nimodipine may have to be withdrawn as it can interfere with attempt to induce hypertension.


Triple H therapy may induce a vagal response,as well as profound diuresis ,requiring administration of large amounts of iv fluids.


Atropine (1 mg im every 3 to 4 hrs ) may be given to maintain the heart rate between 80 and 120 beats/min,and aquous vasopressin(pitressin)( 5 units im) may be adminis
tered to maintain the urine output at less than 200 ml/hr.


The BP is treated to a level necessary to reverse the signs and symptoms of vasospasm or to a maximum of 160 to 200 mmHg systolic,in patients whose aneurysm has been clipped 
If the aneurysm has not been clipped then SBP is increased to only 120 to 150 mmHg.


The elevated BP must be maintained until the vasospasm resolves which usually in 3 to 7 days.


Response to therapy can now be monitored non invasively using the TCD,improvement in vasospasm is associated with a decrease in flow velocity.


PET has been performed in patients not responding to triple H therapy,to diagnose any hypoperfused area which are not infarcted,which will benefit from an improvement in blood flow. CBF values <20 ml/100g/min,have been found in the affected hemispheres of patients with symptomatic vaso
spasm and values<12 ml/100g/min have been associated with irreversible changes.


The BP is manipulated using inotropes to see wether there is any increment in blood flow to these hypoperfused areas.


Hemodilution the last component of triple H therapy is based on the correlation of hematocriet and whole blood viscosity.As the Hematocriet and viscosity decrease,the cerebrovascular resistance corresponding decreases and CBF increases and the oxygen carrying capacity is decrease.


Experimental study that suggested that hematocriet of 33%
provides an optimal balance between viscosity and oxygen carrying capacity and this has been applied clinically.


Phlebotomy or blood transfusion are performed to maintain a hematocriet 33%.


 Non Pharmacologic treatment:
 Reduction of ICP:(1)
 In patient has elevated ICP ,cerebral perfusion may be 
 improved by lowering the ICP.
 Improvement in neurologic status with this treatment 
 alone has been reported.

 Interventional neuroradiology:

Percutaneous angioplasty (PTA):(2,4)


If the patient is in imminent danger from severe diffuse vasospasm refractory to triple H therapy ,these spastic arterial segment may be forcibly dilated by means of small low pressure balloon placed through intra arterial catheter.
In expert hands this associated with the permanent rever
sal of vasospasm and clinical improvement in one half to two thirs of patients but there is a risk that the vessels may rupture and dissect with this technique so the procedure should be restricted to experienced interventional neuro
radiologis.


 Intra arterial papaverine:(2)
 The proximal segment of the anterior cerebral arteries,and 
 distal middle cerebral arteries are not amenable to balloon 
 dilatory because of size or angle of take off.

 The instillation over several hours of high concentration
 of intra arterial papaverine has been associated with rever
 sal of vasospasm in some cases.

 Papaverine ,a phosphodiesterase inhibitor causes the accu
 mulation of cycle adenyl monophosphate within smooth 
 muscle leading to vasodilatation.

 There has been tendency for spasm to recur and the 
 infusion may have to be repeated but it is sometimes 
 associated with clinical improvement.

 However,papaverine can precipitate systemic hypotension 
 and intracranial hypertension so measures to support BP 
 and control ICP  must be immediately available.


 Prophylaxis:(2,3)

 Early surgery permits the mechanical removal of fresh 
 blood clot by suction and irrigation.

 As blood in the subarachnoid space precipitate cereb-
 ral vasospasm,it has been postulated that drugs which 
 dissolve this blood clot may reduce the incidence of 
 cerebral vasospasm and improve outcome.

 Once the offending aneurysm has been secured by a clip 
 it is possible to place tissue plasminogen activator within 
 the subarachnoid space,either at the time of surgery or 
 subsequently through catheters to faciltate the early 
 fibrinolysis the clot ,thus reducing the amount of decaying
 blood pressing against the arteries. 

This appear to be effective way of preventing vasospasm.
 However,a recent trial using tissue plasminogen activator 
 showed a reduction in angiographic vasospasm but no 
 improvement in symptomatic cerebral vasospasm or 
 neurologic deterioration.

 These fibrinolytic agents have a potential to cause 
 bleeding by dissolving normal clot,so only patients at high 
 risk of developing vasospasm should be choosen for this 
 type of prophylaxis.


 Summary 

 One of the most devastating complications of SAH is 
 cerebral vasospasm.

 which can cause delayed focal or diffuse ischaemic 
 neurologic deficits.

 The frequency of occurence as determined by angiography 
 is estimated to be 40% to 60%,however clinically significant 
 and symptomatic vasospasm occurs at lower frequency (20% to 30%).

 Blood in the subarachnoid space precipitate cerebral vaso
 spasm,the component in the blood implicated in pathoge
 nesis of vasospasm is currently thought to be oxyhemoglo
 bine.

 Progressive impairment in level of conciousness or increase 
 in focal neurologic deficit occuring more than four days 
 after bleeding episode should raise the suspicion of cereb  
 ral vasospasm.

 There is general belief that early surgery and the removal 
 of blood reduced the risk of developing cerebral vasospasm
 Numerous drugs have been investigated for prevention or 
 treatment of vasospasm but most are ineffective.

 Calcium channel blockers of which nimodipine has been 
 more extensively studied are the only drugs that have been 
 shown to consistently reduce the incidence of poor 
 outcome by 40% to 70%.

 Triple H therapy aims to increase cerebral perfusion by 
 increasing CBF and improving flow characteristic by 
 haemodilution.

 To optimize therapy and minimize the potential 
 cardiovascular and pulmonary complications,invasive 
 monitors including direct arterial blood pressure,CVP or
 preferably a pulmonary artery catheter are essential.
 If there is no improvement after volume expansion ,the use 
 of inotrope(dopamine,dobutamine and phenylephrine ) are 
 started.


 If the patient is imminent danger from severe diffuse 
 vasospasm or refractory to triple H therapy  then PTA can 
 be alternatif treatment.

 When cerebral arteries are not amenable to balloon 
 dilatory because of size or angle of take off,intra arterial 
 papverine can be choosen.

 REFERENCES :
1.Lam M Arthur :Cerebral aneurysm :Anesthetic 
   concidreation;Cottrell E James,Smith S David;Anesthesia 
   and Neurosurgery ;4th edit.Mosby A harcourt Health 
   Sciences Company ,2000:pp 373-6


2.Weir K Bryce:Intracranial Aneurysm and AV Malformation
   Surgical Consideration ;Albin S Maurice;Textbook of 
   Neuroanesthesia with Neurosurgical and Neuroscience 
   Perspective ;The Mc Graw Hill Companies Newyork,StLouis 
   San Franscisco,1997:pp 852-3.


3.Godsiff S Leisha,Matta FBasil:Intensive care management 
   of intracranial hemorrhage ;Matta F Basil,Menon K David
   Turner M John:Textbook of Neuroanesthesia and Critical 
   Care,Greenwich Medical Media Ltd,London
    2000,pp 335-9.


4.Chang W.J.Cherylee,Bleck P Thomas:Neuroscience Inten
   sive Care:StoneJ.D.Sperry J.Richard;The Neuroanesthesia 
   Handbook;Mosby Year Book Inc.USA,1996;pp457-60.

Sunday, February 26, 2012

Cerebral Vasopasm (PART I )

DEFINITION : (2,3,4)


Vasospasm is the prolonged intense constriction of the larger conduction arteries in the subarachnoid space,which initially surrounded by subarachnoid clot it is likely that spasmogens are released from the breakdown of red blood cell trapped by fibrin mesh in in the the abnormal environment of subarachnoid space.The etiology remain uncertain but appears to be related to the amount and distribution of blood in the subarachnoid space.


This may also be due to local mechanic pressure effects from the high pressure arterial bleeding of the aneurysm or from the clot itself.


Pathogenesis :(1,3)


The vasospastic artery has a structural and pathologic changes within the vessel wall, such as swelling and necrosis of the smooth muscle cells. Although the exact mechanism and cause of spasm have not been completely elucidated,a reasonable hypothesis is that one or more vasoactive substances contained in the blood in the basal cisterns induce changes in the cerebral arteries to cause severe constriction.


Several mediators have been postulated including serotonin
histamine,cathecolamine,prostaglandins,angiotensin,lipid
peroxidase,endothelin and oxyhemoglobin.


The component in the blood implicated in the pathogenesis of vasospasm is currently thouht to be oxyhemoglobin.


The cerebrovascular tone is regulated by a balanced between vasodilatating and vasoconstricting factors.


The suppressived interaction of oxyhemoglobin with endothelium derived relaxing factor nitric oxide (patent vasodilator) coupled with stimulated production of endo
thelin(potent vasoconstrictor) is the postulated cause
of vasocerebral spasm. In experimental vasospasm the increase in the perivascular concentration of oxyhemoglobin and deoxyhemoglobin parallels the time course of vasospasm. In support of this hypothesis,early intracra-
nial operation (within 48 hours) to remove extravasated subarachnoid blood has been shown to be effective in reducing the occurence of vasospasm and associated neurologic deterioration.


INCIDENCE:(1,3)


In study vasospasm accounted for 13,5% the overall morta
lity and major morbidity. 


Not all patients with subarachnoid hemorrhage(SAH) will develop vasospasm and its severity,time course and prognosis are largely inpredictable.


The incidence and severity of delayed cerebral vasospasm have been shown to correlate with the amount and location of blood in the basal cisterns. 


The frequency of occurence as determined by angiography is estimated to be 40% to 60%. 


However,clinically significant and symptomatic vasospasm occurs at a lower frequency (20% to 30%).


This difference may be explained by the varying degree of vasospasm. As established lower limit of cerebral blood flow(CBF) compatible with normal brain function is appro
ximately 15 to 20 ml/100 g/min.


Thus considerable reduction in CBF can occur from vaso
spasm without clinical symptoms.


When symptomatic vasospasm develops, approximately 50% of the patients will die or be left with serious residual neurologic deficits.


Typically angiographically detectable vasospasm is not seen until 72 hrs after SAH, the incidence peaks 7 days after SAH and it is seldom seen after 2 weeks.The onset of vasospasm is generally 3-5 days after SAH, and duration of 2-4 weeks.


CLINICAL MANIFESTATION: (1,2)


Clinical manifestation most commonly gradually but may also occur abruptly include a decrease in the level of conciousness new onset of focal sign and mutism. 
Hijdra et al found that the patients with delayed cerebral ischemia from vasospasm had a decreased in the level of conciousness that may be accompanied by but was never preceded by focal signs.


Progressive impairment in level of conciousness or increase in focal neurologic deficit occuring more than four days after SAH should raise the suspicion of cerebral vasospasm.


DIAGNOSIS: (2,3)


Cerebral angiography remains the gold standard for diagno
sing vasospasm which is seen as smooth vasoconstriction in cerebral vessel.


Vasospasm may be limited the area surrounding the rup
tured aneurysm or it may be widespread when it is asso
ciated with poor prognosis.


Although an angiogram remains the definitive diagnostic tool for vasospasm,and although transcranial Doppler ultrasonography (TCD) is unreliable as a measure of CBF in patients with SAH because vasospasm associated changes in vessel diameter, it has become valuable for diagnosing vaso
spasm non invasively prior the onset of clinical symptoms.


As the vessel diameter is reduced for a given blood flow,red blood cell velocity (FV) increases. 


Hence, cerebralvasospasm is considered present when FV > 12o cm/sec or the ratio between the FV in the middle cerebral aretery(MCA) and the FV in the internal carotid artery(ICA) exceeds 3, should decrease with effective treatment.


TCD is increasingly being used to diagnose vasospasm especially in sedated and ventilated patients, as it has advantage of being a noninvasive bedside test and TCD results did not have any adverse influence on management or outcome.


Cerebral angiography should be performed in any patient with clinically suspected vasospasm despite negative TCD findings.


Other methods which can be used to diagnose vasospasm include photonemision tomography and positron emission tomography(PET).


PET has been performed in patients not responding to triple Htheraphy,the aim is to diagnose any hypoperfused area which are not infracted.


Which will benefit from an improvement in blood flow.
CBF values <20 ml/100g/min have been found in the affected hemisphere of patients with symptomatic vasospasm and values <12ml/100g/min have been asso
ciated with irreversible changes.


to be confinued

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