**1. Introduction**

The World Health Organization in 1980 defined stroke as "the rapidly developed clinical signs of focal (or global) disturbance of cerebral function, with symptoms lasting 24 hours or longer or leading to death, with no apparent cause other than of vascular origin" [1]. In 2013, the American Stroke Association for the 21st century came up with a new broader definition of stroke [2]. The new definition of stroke includes "brain, spinal cord, or retinal cell death attributable to ischemia, based on 1. pathological, imaging, or other objective evidence of cerebral, spinal cord, or retinal focal ischemic injury in a defined vascular distribution; or 2. clinical evidence of cerebral, spinal cord, or retinal focal ischemic injury based on symptoms persisting ≥24 hours or until death, and other etiologies excluded" [2]. Stroke is a major cause of morbidity and it remains the second leading cause of death worldwide after ischemic heart disease [3, 4]. Stroke is also the third most common cause of disability with significant increase in stroke burden in the world and especially in developing countries [5]. On average in the United States (U.S.) someone has a stroke every 40 seconds [6].

Stroke is divided into ischemic and hemorrhagic stroke. Hemorrhagic stroke is further divided into intracerebral and subarachnoid hemorrhage. Approximately 85% of all strokes are ischemic with the remaining 15% being hemorrhagic [7]. We have currently moved away from using terms such as "cerebrovascular accident" and "reversible ischemic neurologic deficit" [7].

Transient ischemic attacks (TIA) also known as "warning strokes" are defined by the American Heart Association and American Stroke association as "brief episodes of neurological dysfunction resulting from focal cerebral ischemia not associated with permanent cerebral infarction" [8]. Although it is difficult to count the exact numbers of patients suffering from TIAs, in the U.S. this number has been estimated to be 200,000–500,000 per year [8].

Ischemic stroke is the result of a blockade of the arteries that supply the brain. The most common criteria used for classifying the causes of ischemic stroke are the Trial of ORG 10172 in Acute Stroke Treatment (TOAST) criteria [9]. The TOAST criteria group the causes for ischemic stroke into five main groups which include: 1) large-artery atherosclerosis, 2) cardioembolic, 3) small-vessel occlusion, 4) stroke of other determined etiology and 5) stroke of undetermined etiology [9].

Hemorrhagic stroke results from the rupture of a blood vessel resulting in blood outside the vessel in the brain parenchyma. Intracerebral hemorrhage has an annual incidence of 10–30 per 100,000 population and there has been an 18% increase in intracerebral hemorrhage in the last ten years [10]. Subarachnoid hemorrhage is the presence of blood in the subarachnoid space, the space between the arachnoid mater and the pia mater. Common causes of subarachnoid hemorrhage include trauma, rupture of an intracranial aneurysm and perimesencephalic hemorrhage [11]. The overall global incidence of aneurysmal subarachnoid hemorrhage is 7.9 per 100,000 people per year [12]. Rupture of a cerebral aneurysm resulting in subarachnoid hemorrhage remains a neurosurgical emergency. The mortality rate for patients hospitalized with non-traumatic subarachnoid hemorrhage can be higher than 25% [13].

Risk factors of stroke have been well established some of which are hypertension, hyperlipidemia, diabetes and smoking [14]. Prevention of stroke can be achieved by managing the above risk factors. Prevention of stroke is key as survivors of stroke often face poor functional outcome as well as cognitive and physiological impairment [15].

The National Institutes of Health Stroke Scale (NIHSS) is a scale used by medical personnel to determine the severity of the neurological deficit following a stroke [16]. The scale ranges from 0 to 42 with higher scores reflecting a worse neurological impairment [16]. The NIHSS can also be used after treatment to assess any improvement in clinical symptoms. The NIHSS is probably the most widely used stroke scale. However due to some limitations efforts are made to improve and modify it [17]. Another widely used scale to predict functional outcome following a stroke is the modified Ranking Scale (mRS) [18]. The mRS is a categorical scale ranging from 0 to 6 with score 0 referring to a fully independent patient and score 6 referring to someone being dead [18].

The key in managing a patient who is experiencing a stroke is early recognition of symptoms. Any patient who is suspected of having a stroke should undergo emergent computed tomography of the brain in order to determine whether the stroke is ischemic or hemorrhagic in nature. If hemorrhagic stroke is excluded, ischemic stroke is suspected and if there are no contraindications intravenous tissue plasminogen (tPA) activator should be administered. Computed tomography perfusion (CTP) is necessary to identify the salvageable brain region. Computed cerebral angiography (CTA) should also be performed to look for any large vessel occlusion. If a proximal large vessel occlusion in the anterior circulation is identified patients who meet the criteria can undergo endovascular mechanical thrombectomy to relieve the obstruction.

*The History of Neurosurgical Management of Ischemic Stroke DOI: http://dx.doi.org/10.5772/intechopen.95477*

Following mechanical thrombectomy the modified Thrombolysis in Cerebral Infarction (mTICI) grade is used to determine the percent of arterial revascularization. Over the years the scale has been modified. The original scale had scores ranging from 0 to 4 [19]. The scores on the most recent scale range from 0 to 3 with score 2 being divided into a, b and c [20]. mTICI 0 refers to no perfusion or anterograde flow beyond the site of occlusion [20]. mTICI 1 refers to penetration but no perfusion [20]. mTICI 2a refers to some perfusion with distal branch filling of less than 50% of territory visualized [20]. mTICI 2b refers to substantial perfusion with distal branch filling of more than equal to 50% of territory visualized [20]. mTICI 2c refers to near complete perfusion except for slow flow in a few distal cortical vessels, or presence of small distal cortical emboli [20]. mTICI 3 refers to complete perfusion with normal filling of distal branches [20].

Stroke is a health condition that neurosurgeons deal with on an everyday basis. Over the years the management of ischemic stroke is a field that has been rapidly evolving and advancing. The focus of this book chapter will be to discuss the history that has led to the current techniques used by neurosurgeons for treating ischemic stroke.
