Irreversible disability is traditionally associated with cerebral vascular disease (CVA) and it is under-estimated that there are 2 million fatalities from vascular disease every year. Although medical measures help in acute ischemia, they are only palliative in an established stroke and in prevention of a repeat stroke. 

Cerebral revascularization is the goal. Of late, there is an  increasing acceptance of surgical revascularization even in acute episodes. 

Etiology:

Arterial thrombosis and atherosclerosis with occlusion of the cerebral arteries is the single most common cause of stroke in more than 50 percent of patients.  

Thirty to 50 percent of the cases have had previous transient ischemic attacks. 

Other  rarer causes include trauma to the carotid/vertebral arteries, collagen diseases, moyamoya disease, fibromuscular dysplasia, vasospastic conditions (SAH, migraine etc), and the conditions which alter the rheological properties if the blood such as,  polycythemia, leukemia etc.  

There are risk factors, such as, hypertension, hypercholesterolemia, atherselerosis, cardiac abnormalities, diabetes mellitus, obesity, and lack of physical activity.. 

Clinical features:

The earliest sign of the CVA is the transient ischemic attack (TIA). The other findings may be a history of diplopia, atherosclerosis of the retinal arteries, speech difficulties, motor or sensory changes, abnormalities of cerebellar function etc.

Transient ischemic attacks (TIAs) are usually described as related to the carotid or vertebral-basilar arterial systems. It is defined as an acute cerebral dysfunction resulting from vascular problem, which recovers within 24 hours. 

Carotid territory: 

The classic history for transient ischemic attack in the carotid system is one of swift onset of contralateral weakness or numbness of the arm or leg. Dysphasia occurs if the dominant hemisphere is involved. Impaired vision of the eye on the side of the diminished carotid flow takes place. This clinical phenomenon usually indicates a decrease in regional cerebral perfusion, and produces a neurological deficit, the onset of which is usually sudden with gradual progression of the symptomatology.

Carotid artery occlusion is caused by atherosclerosis, arteriosclerosis and atheroma, and is compounded by the extension of cholesterol and calcium deposits into the branches of the common carotid artery, specifically the internal carotid artery.

There are five items, which would bring one to suspect involvement of the carotid arteries:

1. Blindness in one eye during the TIA attack.

2. Emboli in the retinal vessels.

3. Bruit over the carotid artery.

4. Significant lowering of the retinal arterial pressure on the affected side.

5. Any sign of retinal artery ischemia.

Vertebral-basilar territory:  

Damage to this system is also characterized by a very swift onset of symptoms with neurological phenomenon such as ataxia, monoparesis, hemiparesis, quadriplegia, numbness (frequently shifting from one side to the other), vertigo, defects in either visual field, diplopia, dysarthria, aphasia and occasionally, clouding of consciousness. Vertigo is perhaps the most common symptom of TIA in this distribution.

Prolonged reversible ischemic defect (PRIND) is one where the signs and symptoms lasts for a week followed by recovery.

Progressing stroke (PS) is one where the deficit continues to progress in a stepwise fashion despite adequate medical therapy.  

Stroke is a sudden, unheralded progressive neurological deficit due to a vascular pathology; the deficit becomes complete in few hours. It is usually associated with altered sensorium and hypertension. 

Associated  carotidynia (pain over the carotids) suggest a carotid pathology.

Investigations:

TIAs should be regarded as an emergency. The risk of stroke is greatest in the weeks following TIA and patients should be referred for further investigations at the earliest. The initial evaluation of a patient in whom a transient ischemic attack is suspected should include laboratory tests, electrocardiography, and imaging studies. Since imaging of the head may reveal a nonischemic cause, such as a tumor or subdural hematoma, and may provide information about the cause of ischemia, it is recommended that CT or MRI of the head be part of the evaluation of all patients. Doppler ultrasonography or other noninvasive investigations of the carotids should be performed rapidly, ideally within 24 hours.

MRI is more sensitive, in particular for previous hemorrhage. MRAngiography, a noninvasive test, permits the visualization of blood flow in vessels without the need for catheters or contrast agents.  The technology can yield information regarding collateral blood flow and is nearly as effective as conventional angiography in estimating disease at the carotid bifurcation. It is suitable for replacing the invasive conventional angiography method in most cases. Further technical developments with regard to spatial resolution are still required for improved visualization of small vessels and terminal branches of intracranial vessels.

Ultrasonography, being cost effective, should be used as a screening tool to exclude patients with no carotid artery disease from further testing.

B-mode imaging provides images of various levels, or planes, enabling the creation of a three-dimensional image of the carotid artery wall and surround structures.  This technique provides information on the type and extent of arterial damage, but blood clots sometimes do not appear and the method cannot distinguish a severely narrowed from a completely occluded artery. 

However, its reliability is highly dependent on the technician. The recent availability of ultrasound contrast agents helps to distinguish between pseudo- and true occlusions, improves ultrasound images and should help to reduce operator variability. Color and spectral Doppler ultrasound are now recognized as the best screening tests for carotid artery stenosis. The evidence for its use as the sole diagnostic imaging modality prior to carotid endarterectomy is examined. Supplementary imaging is especially advisable when results of DUS are technically limited.

Transcranial Doppler (TCD) assesses intracranial arterial flow in the distal ICA, the middle, anterior, and posterior cerebral artery stems, and ophthalmic artery. Hemodynamic significance extracranial and intracranial ICA occlusion and the availability of collateral circulation may be studied satisfactorily.Transorbital (ophthalmic artery), submandibular (distal ICA), transtemporal (Anterior cerebral. Middle cerebral and posterior cerebral), and foramen magnum (posterior circulation) approaches are employed for a comprehensive assessment. Serial TCD examination may reveal dynamic changes in cerebral circulation that may be missed on a single MRA study. Preoperative TCD can be used to identify patients who do not require a shunt during carotid endarterectomy. In acute ischemic stroke, TCD can be used to elucidate stroke mechanisms, plan and monitor treatment, and determine prognosis. In an era when stroke is increasingly being recognized as an emergency requiring immediate treatment, TCD may be capable of providing rapid information about the hemodynamic status of the cerebral circulation, within the time frame of the rather small 'therapeutic window'.

Ophthalmodynametry and oculoplethysmography offer an indirect indication of ipsilateral carotid occlusion. Ischemia of the macular region is necessary to produce transient monocular blindness and local retinal blood flow has been reduced to the flow threshold of electrical failure in patient. Ophthalmic artery flow reversal is not only quite specific for severe ICA disease, and also provides additional hemodynamic insights (i.e., the inadequacy of other collateral channels such as the anterior communicating artery.

Doppler CO2 / Acetazolamide (diamox) test: CBF measured early after acetazolamide administration could be useful to confirm the clinical diagnosis of TIA.  No increase in CBF during hypercapnia or following acetazolamide suggests that the cerebral arterioles are maximally dilated and the procedures to improve the blood flow, such as EC-IC bypass will not help.

Surgical revascularization:

a) Carotid territory:

The overall risk of a stroke, following a TIA, is about 12% during the first year, rising to 30% within 5 years. 

The risk is higher, about 30%, with internal carotid stenosis, whereas those with complete carotid stenosis are unlikely to develop a stoke in the same territory. 

The stenosis will progress in more than 50% of cases over the subsequent 1-5 years.

The role of carotid endarterectomy is now well established. 

Various other procedures are being tried with no satisfactory evidence based benefit.

1) Carotid endarterectomy: 

Indications:

The ideal patient for carotid endarterectomy is one who presents with a history of transient ischemic attack, hemispheric or retinal and  has no neurological deficit on physical examination and who has a stenotic lesion at the orifice of the internal carotid artery.  

TIAs of embolic origin do well with endarterectomy, whereas, the flow related ones do not do as well. 

Patients with stroke within previous 6 months with 70%-99% stenosis of ipsilateral ICA. 

Patients with lesser stenosis but an ulcerative plaque.

Traumatic occlusion of the carotid and spontaneous dissection of the carotid may be considered for endarterectomy.

Acute stroke, when the procedure can be performed within 2-3 hours of the onset (with no evidence of infarct on CT), is a controversial indication, becoming less and less controversial of late.

Progressive stroke despite effective medical measures, and occlusion of an asymptomatic carotid, while investigating the symptomatic carotid or vertebro basilar territory  are other controversial indications.

Surgical technique:

Preoperative counseling is important as preparation of the patient mentally helps a great deal in overcoming the fear and anxiety. If the patient is on antiplatelets already, ASA may be continued through the procedure. But Clopidogrel is stopped two days pre operatively in our practice.

In the operative room patient is sedated with 1mg Medzolam intravenously after securing venous access and arterial pressure monitoring catheter. Arterial pressure is monitored continuously as fluctuation during the procedure can affect the cerebral circulation.

Positioning of the patient is extremely important as hyperextension of the neck may kink the vetebrals which will be the likely source of blood supply during cross clamping of ICA.

Intraop monitoring: 1) EEG: Electroencephalography is a sensitive detector of cerebral ischemia and a valuable tool for determination of need for shunting during carotid endarterectomy. A statistically significant increase in intraoperative stroke rate is associated with the development of an abnormal EEG (1.1%), contralateral internal carotid artery occlusion (1.8%), and the combination of both abnormal EEG and contralateral internal carotid occlusion (3.3%).

2) SSEP: If available, use of SSEP is the ideal monitoring under general anesthesia. Registration of SEPs is simple to perform and indicates with a high sensitivity and specificity critical cerebral hypoperfusion during cross-clamping. Progressive reduction of up to 50% of N20, P25 amplitude is suggestive of ischemia. SSEPs not only help to identify patients with insufficient collateral blood flow who benefit from specific cerebral protection, such as shunt, but also to avoid improper and hazardous application of these measures in patients with sufficient cerebral perfusion. In addition, correct shunt function is immediately indicated by recovering potentials.  

3) Stump pressure measurement: Measurement of ICA stump backpressure helps in deciding on the need for a shunt. Reports  suggest that surgery without a shunt when the ICA back pressure is low(less than 50 mm/hg), produce significant deficit.

4) Transcranial Doppler (TCD): The perioperative stroke rate can be reduced by appropriate measures, taken by the surgeons, based on findings of TCD monitoring.TCD will help detect high blood flow velocities.The clinical significance of bilateral flow velocity increases soon after surgery is uncertain, but very high blood flow velocities might be a signal for cerebrovascular hyperperfusion. In those patients, increased postoperative surveillance is recommended.  

None of the haemodynamic criteria by stump pressure and TCD are absolutely reliable in predicting the need for carotid shunt. The usefulness of monitoring cerebral function during the procedure is closely related to the experience of the surgical team. No one method of monitoring in selective shunting has been shown to produce better outcomes. No prospective randomised or quasi-randomised trials have been performed and the conclusions therefore remain unchanged. Recommendations whether to practise cerebral monitoring or not, and what method should be used for this purpose, cannot be given presently.

Procedure: We prefer regional anesthesia. It obliviates the need for extensive introperative monitoring for cerebral ischemia. Careful assessment of cerebral perfusion can be made by direct interaction with the patient. This is by far the best mode of assessment of cerebral perfusion when compared to other modalities like TCD and SSEP. Regional anesthesia is obtained by both superficial and deep cervical block. Deep cervical block involves infiltration of local anesthetic agents around C2, 3, and 4 at the exit foramina. Superficial block involves infiltration around the cervical plexus at the lateral border of the sternocleidomastoid muscle at the level of external jugular vein. We use approximately 40cc of 0.375% Bupivacaine for this as the anesthetic effect lasts as long as 6-8hrs.

Just before making the incision patient is given Fentanyl 25mg intavenously for additional sedation. Incision is made parallel to anterior border of sternomastoid from the level of thyroid in cartilage to just below mastoid process.

recurrent plaque or with an unexplained thrombus at the site of previous endarterectomy. Clamps are sequentially released after arteriotomy closure. External carotid circulation is established first as any small debris from the operative site may be released into extra cerebral circulation. Internal carotid clamp is released at the end. If the haemostasis is satisfactory reversal of the heparin may not be required.

The wound is closed after placing a suction drain as the wound is likely to ooze due to preoperative antiplatelet therapy.

Post operatively, close neurological observation is necessary by a dedicated nurse. Post operatively patient can be started on oral fluids after two hours and all the medication as before including anti platelets. There is no indication for routine anticoagulant therapy.

Use of Shunt: The only method currently accepted by all surgeons to achieve cerebral protection, is the use of shunt during carotid endarterectomy. The relative risk of shunting versus not shunting during carotid endarterectomy was analyzed by Sundt TM jr et al retrospectively in 1935 cases undergoing carotid endarterectomy for carotid ulcerative stenosis. The need for shunting was based on a correlation between electroencephalographic changes and a fall in cerebral blood flow below the critical level required for adequate perfusion during the period of carotid occlusion. Patients were divided into four risk categories for surgery, based on medical and neurological risks and angiographic findings. Shunts were required in 30% of the low risk group and 56% of the high risk group. Based on the severity of reductions of cerebral blood flow during the period of carotid occlusion it is concluded that 12% of all patients would have sustained a major deficit, 15% a minor or transient deficit, and 20% a transient deficit without shunting. The risk of shunting 792 cases in this series was 0.5%. Overall minor morbidity, major morbidity, and mortality each approximated 1% in this series.

It has been suggested that external shunts, placed between the common carotid artery and the internal carotid artery (ICA), is safe and efficacious in cases that do not permit the placement of an internal shunt. A new type of temporary extraluminal shunt, connecting the femoral to the internal carotid artery with the interposition of a roller pumps to regulate the blood flow has been reported. This method allows one to perform carotid endarterectomy without interrupting the blood flow to the brain.

Complications:

The operative mortality and morbidity  is 1-5% in various studies.

The majority of strokes after carotid endarterectomy are thromboembolic and many can be traced to technical failures, such as the creation of an intimal flap, incomplete plaque removal, or the creation of kinking or stenosis during arterial closure. Severe and damaging cross-clamp ischemia in patients with poor collateral flow to the ipsilateral hemisphere underlies fewer postoperative strokes but may be detectable with intraoperative cerebral monitoring. 

Intraoperative shunts may reduce the risk of stroke in this subgroup of patients; some surgeons use intraoperative shunts in all patients.

Microsurgical method increases the precision and safety of every aspect of carotid endarterectomy, including complete plaque removal, prevention of intimal flaps, nonstenosing arteriotomy closure, and intraoperative shunt insertion when necessary.

Restenosis occurs in about 20%; use of dacron or vein patch during arteriotomy closure when ICA internal diameter is <5mm is recommended.

To improve the prospects for postoperative carotid artery patency, use of antiplatelet therapy both preoperatively and postoperatively is advised.

Results:  The first report from the North American Symptomatic Carotid  Endarterectomy Trial (NASCET), which concluded that carotid endarterectomy is highly beneficial to patients with recent hemispheric and retinal transient ischemic attacks or nondisabling strokes and ipsi-lateral high-grade stenosis (70-99%) of the internal carotid artery, reported a cumulative 9% risk of any ipsilateral stroke over 2 years in the surgical group of 328 patients. In the perioperative period, 18 surgical patients (5.5%) had cerebrovascular events: 12 minor (3.7%), 5 major (1.5%), and 1 fatal (0.3%).

pre-op     post-op                           angio - ICA stenosis

In that study, three of the major strokes were due to carotid occlusion in the early hours after endarterectomy, and 10 of the minor strokes were also delayed in onset and were presumably embolic.

MRC European Carotid Surgery Trial (ECST) suggests the patients with a  stenosis <30% need not be operated; benefit of surgery in those with 30-69% stenosis is not conclusive.

2) Extracranial to intracranial (EC-IC) bypass:

Superficial temporal to middle cerebral artery bypass (STA-MCA): Small vessel disease (about 20% of all ischemic patients), middle cerebral artery occlusion where endovascular thrombectomy has failed or is not feasible, and total ICA occlusion may benefit from a EC-IC bypass procedure. 

This procedure was popular in the 70s. It involves anastomosis of the superficial temporal artery to one of the cortical branches of the middle cerebral artery.

The skin in incised over the proximal STA, just above the zygoma. The STA has at least two major branches (frontal and parietal) and they should both be followed distally. The STA is dissected with a small cuff of tissue to prevent vessel injury. The larger branch is freed.

A small craniotomy centered over the sylvian fissure is made and a recipient artery is selected and dissected from the archnoid to follow anastomosis.

The STA is ligated and divided and the proximal STA is occluded with a temporary clip.

The recipient art is transiently occluded between two temporary clips and an end to side anastomosis is performed with 10-0 monofilament suture. Cerebro-protective techniques, including hypothermia and barbiturates help.

This provides initial flows of 25-50ml / minute; with time the bypass may mature, allowing enlargement of STA and delivery of a higher flow. Occipital artery to the intracranial circulation has also been tried.

Interposition vein graft is recommended by some, especially when STA is not satisfactory.

Complications include aneurysmal dilatation and rupture of the graft and emboli from the graft site.

Anecdotal reports and uncontrolled patient series suggested that STA-MCA bypass may be beneficial. However the National institutes of health (NIH) study in 1985 concluded that these procedures do not help in preventing a stroke, despite an overall graft patency rate of 96% and low surgical morbidity. They may have a place when everything else fails in the highly selected patients where the metabolic reserve studies suggest a compromised CBF. In the treatment of inoperable ICA giant aneurysms where the risk of ischemic complications due to ICA ligation is high, EC-IC bypass may be used as a prelude to ICA ligation.  Chronic biochemical abnormalities due to brain ischemia may improve after cerebral revascularization.

Vertebro-basilar territory:

The cerebellar infarctions carry poor prognosis with an acute mortality rate of 20-30%. They are mostly due to poor flow (due to stenosis and poor collaterals) due to diffuse atherosclerosis of the vessels. Medical therapy is the first line of therapy. Several procedures have been tried in those with persisting symptoms. There has been no randomized study.

The simplest procedure, perhaps, is carotid endarterectomy if a significant stenosis is found while investigating a vertebrobasilar TIA; the stenosed carotid may be asymptomatic. It is most readily accepted if the angiogram shows filling of the posterior cerebral artery via the stenotic ICA, or filling of the posterior circulation from the ICA because of vertebral occlusion or a persistent hypoglossal or trigeminal artery.

Good outcome with vertebral endarterectomy, which is similar to carotid endarterectomy, has been reported. Posterior circulation bypass ( occipital artery to PICA for occlusion proximal to the PICA and a superior cerebellar artery or P1 segment of the posterior cerebral artery anastomosis for lesions at the mid or distal basilar) have been described.

Extra cranially, the left subclavian artery, next to the carotids and the vertebrals, is most commonly involved in atheroscleorosis. Subclavian syndrome is most commonly treated by carotid-subclavian bypass. The cervical vertebral artery may occasionally compressed by cervical osteophytes. Anterior cervical decompression ,reportedly, helps.

b) Indirect revascularization procedures:

Patients present with stroke or intracranial hemorrhage due to bleeding from the friable vessels with major morbidity and mortality. Children usually present with cerebral ischemia. Intracranial hemorrhage is common in adults. Without treatment, there is progressive deterioration of neurologic function and re-hemorrhage.

Treatment of all these patients with nonatherosclerotic occlusive diseases is similar to that of moyamoya patients. Medical therapy with vasodilators, steroids, and antibiotics is only minimally effective. Various surgical procedures have been tried with mixed results.

STA-MCA bypass in adults, encephloduroarteriosynangiosis, encephalomyosynangiosis, and encephaloomental-synangiosis in children are the available procedures. Direct superficial temporal artery to middle cerebral artery bypass is considered the treatment of choice, although its efficacy, particularly for hemorrhagic disease, remains uncertain.

Encephalomyosynangiosis involves direct placement of temporalis muscle on the cerebral cortex. This may induce seizures.

Encephloduroarteriosynangiosis developed by Matsushima  is popular. STA is mobilized and placed directly on the cortex. The free artery with a cuff of surrounding soft tissue is simply sutured to the dura.

Encephaloomental-synangiosis (omental-cerebral transposition) may provide an alternative. The omentum is mobilized from the abdomen in a subcutaneous tunnel and placed over cerebral cortex as a pedicle graft or, as a free graft with microsurgical anastomosis of the gastroepiploic artery and vein to the STA and the superficial temporal vein. Omentum contains biologically active substances taking part in neural transmission and has angiogenic and neurotrophic action.

Combined procedures give the best results. Spontaneously developed leptomeningeal anastomosis might be the key factor for the efficacy of indirect bypass in elderly patients with moyamoya /stenotic cerebrovascular disease. There is no controlled study available. Satisfactory results are reported. 

 Surgery for Acute Stroke:

To appreciate the role of surgery in acute stroke, it is imperative to understand the pathophysiology of stroke.

Recently, the effectiveness of many medical therapies for brain edema and the subsequent increased ICP has been challenged. Recent studies have shown a very high mortality rate despite aggressive medical treatment strategies to lower ICP, which have included osmotherapy, hyperventilation, barbiturate administration, hypothermia, and anticoagulation therapy guided by ICP monitoring. Compared with these, decompressive craniectomy seems to result in a much better outcome; surgical decompression should be performed before inducing deep barbiturate coma in these patients; a surgical decompression performed after failure of ultrahigh barbiturates is too late.

1) Craniectomy and decompression:

A decompressive procedure in selected stroke patients is the most practiced surgical intervention in acute strokes. Any surgery should be effective, rational, and safe. An ipsilateral decompressive surgery fulfils all three criteria. The procedure is, certainly, simple and safe.

The intracranial mass effect can be compensated without an increase in ICP by resorption of cerebrospinal fluid (CSF) and by shifting CSF into the spinal canal. When the reserve spaces become completely exhausted, mass effect leads to an exponential increase in ICP. The equation is expressed by the pressure-volume curve. The studies provide evidence that decompression leads to a shift to the right of the pressure-volume curve and, therefore, to a massive increase in compliance and a reduction of ICP. The rationale for decompressive surgery is supported by these studies.

The available results suggest the effectiveness of decompressive surgery as a salvage procedure.

Associated illnesses and the attitude of the family members to accept a severe neurological deficit, especially in developing countries where there is no adequate rehabilitation centers, must also be considered. As in any surgery, patient selection, and meticulous postoperative management play a major role in the outcome. Associated illnesses must be attended to.

The aim is patient salvage during the acute period of brain swelling. None of the available medical therapies provide substantial relief from the oedema and raised ICP, or at best, they are temporizing in most cases.

The technique is simple. Judicious timing is the key for success. Craniectomy should be performed early, before severe impairment of brain perfusion occurs. Computerized tomography might be able to predict the dynamics of the ensuing clinical course to assist in indicating early intervention in some patients. There are no systematic reports about quantitative analysis of the size of craniectomy required to be effective. Traditionaly, craniectomy is planned according to the area of infarct. A wide craniectomy with a duraplasty is, routinely, recommended.

Ideally, as described by Cushing,, the craniectomy should extend to the base and include drilling of the sphenoid ridge for adequate decompression. Achieving a decompression down to the floor of the middle fossa (subtemporal decompression) seems to be important in this surgical technique, because this procedure relieves pressure from the basal temporal lobe. Good results with this technique were reported even though this form faces the risk of temporal lobe herniation and necrosis. As the dura is opened, pale infracted brain herniates out. The herniation may subside with hyperventilation and osmotherapy. The author recommends excision of persistent herniated brain to prevent strangulation and necrosis. Duraplasty is performed with either silastic lyodura or pericranial grafts.The graft is secured with sutures in a way that allowed the initial incision to spread not more than 2 to 3 cm.This achieves smooth bulging rather than fungus like herniation of brain into the craniectomy, avoiding shearing injuries, impairment of venous drainage, and enhancement of cerebral edema. It is also recommended that in bifrontal craniectomy, the sphenoidal ridges and the anterior walls of the middle cranial fossa be preserved to prevent temporal lobe forward migration. Some groups have suggested resection of infarcted and even noninfarcted brain tissue. Some others recommend resection of the infarcted cerebral tissue and a temporal lobectomy. Japanese surgeons recommend additional excision of the hippocampal gyrus also to relieve peduncle compression, and blockage of cerebrospinal fluid circulation. Another small group of surgeons include a slit in the tentorium to relieve further compression. The author recommends a subdural positive pressure drainage at the end of the procedure helps to facilitate CSF drainage if required post operatively and may be incorporated with an ICP monitor.

The author recommends that conservative measures, such as hyperventilation and osmotherapy, must be tried before surgery is considered and that the decompressive procedure is performed prior to frank clinical deterioration. Ideally, the patient should be young with a GCS of >5, and no serious systemic illness, and must have a supporting family. There may be occasions when the patient selection needs to be individualized. The procedure is mainly to give the maximum chance to preserve life. There is a group of reluctant surgeons who feel, a decompressive procedure do not alter the final outcome. Discouraging outcomes in patients do not invalidate the method; good results confirm its usefulness. The increase in brain edema after decompressive craniectomy led to a discussion in the neurosurgical literature and to questioning the usefulness of the procedure when treating severely brain-injured patients. Brain edema only increases if the brain is already irreversibly severely damaged. Such patients have a poor prognosis, which is no argument against decompressive craniectomy. At present decompressive surgery might be the most promising therapeutic option. For decisive answers, randomized, controlled clinical trials are needed.

Cerebellar infarcts: Older hypertensive men with diffuse atherosclerosis are commonly affected. Previous myocardial infarction or cerebral infarcts are often noted together.Cardiogenic embolus is thought to be the etiological factor in about 50% of the cases. Trauma is an occasional cause. Pediatric group is being recognized increasingly.

The infarct is usually unilateral, and the PICA territory (posteroinferior aspect of the cerebellum) is the site involved. The superior cerebellar artery is an uncommon site of occlusion. Extensive infarction may involve 1/3 or1/2 of the hemisphere and brainstem compression. 25% of them are hemorrhagic.

 2) Revascularization procedures:

The role of revascularization procedures in acute stroke is still in the experimental stage. Emergency carotid endarterectomy is a controversial indication, becoming less and less controversial of late. Patients must have angiographically demonstrated lesion and no infarction in a CT. There is no randomized trial. Tissue plasminogen and interventional endovascular procedures are more often preferred.

Recent reports suggest moderate success of emergency carotid endarterectomy in patients a) with cresendo TIAs, b) with severe stenosis in angiography, and c) with disappearance of a previously auscultated bruit, presumably indicating acute occlusion. The presence of good collateral flow is a favorable prognostic sign. The technique is the same as in elective endarterectomy. Clinical results are best in patients with mild to moderate deficit and a rapid course from onset of deficit to surgery.

Despite excellent postoperative results, the outcomes in patients after STA-MCA anastomoses are not better than the results from medically treated patients. Other procedures such as posterior circulation bypass, vertebral endarterctomy, arterial anastomses, and corrction of subclavian steal have not been tested sufficiently.

Hemorrhagic transformation is frequently seen on CT scans obtained in the subacute phase of ischemic stroke. Its prognostic value is controversial. Hemorrhagic transformation of an ischemic infarct is managed the same way as an ischemic infarct is.

Hemorrhagic stroke: (discussed elsewhere)