A stroke, much like a heart attack, is a condition involving obstruction of blood vessels. However, while a heart attack typically results from the prevention of blood circulation in the arteries, strokes are the prevention of blood circulation in the brain. Stroke is the third-leading cause of death in the United States and the second-leading cause of death worldwide. Those who survive may struggle with serious disability and impairment, which is why treatments like left-side stroke recovery and right-side stroke recovery are so crucial.
Knowledge of the vascular anatomy, the network of blood vessels in the brain, can help us better determine the exact size and location of a stroke. This, in turn, is helpful in planning strategies for stroke patients’ recovery.
The brain is composed of the paired cerebral hemispheres (the cerebrum), the diencephalon, the brain stem, and the cerebellum.
The cerebrum is the largest portion of the brain, and contains a convoluted series of ridges. This region of the brain is divided into two hemispheres by a long fissure called the longitudinal fissure, and is further subdivided by into smaller lobes. The name of each lobe corresponds to the bone that covers it.
The frontal lobe contains four gyri, or ridges. One gyrus (the pre-central gyrus) controls all the major movements of the body. The frontal eye fields control eye movements. The motor speech area, also known as Broca’s area, controls speech. Significantly, the motor speech area is located in whichever hemisphere is dominant in that individual. For example, for right-handed individuals it will be in the left hemisphere. This area is especially susceptible to damage by strokes. Patients who suffer strokes in this region may be unable to articulate in words what they’re capable of thinking.
The parietal lobe of the cerebrum is the primary sensory area, and is concerned with sensations like touch, temperature, and pain.
The occipital lobe primarily functions to process visual information. The temporal lobe, composed of three gyri, processes auditory information. One part of the temporal lobe, Wernicke’s area, serves language and comprehension. Strokes in this area can prevent patients from speaking understandably. Finally, the limbic lobe, hidden deep in the brain, belongs to the limbic system which helps manage emotions.
The diencephalon lies between the cerebrum and the brain stem, and is composed of the thalamus, hypothalamus, and epithalamus.
Like the cerebrum, the cerebellum is divided into two lobes. Located posterior to the occipital and parietal lobes, the cerebellum coordinates balance and smooth motion of the musculoskeletal system.
Finally, the brain stem at the lower back of the brain consists of the midbrain, pons, and medulla oblongata. The superior colliculus of the midbrain is responsible for reflexes to visual stimuli in the head, eyes, and body, while the inferior colliculus is responsible for auditory stimuli. The pons has a bulbous appearance and helps coordinate information between the cerebrum and cerebellum. The pons is separated from the cerebellum by a ventricle containing cerebral spinal fluid. The medulla oblongata contains cardiac and respiratory centers that regulate the heart and breathing.
The posterior portion of the brain receives blood from the basilar artery, a union of two vertebral arteries that pass through the cervical vertebrae and enter the cranium through a pass known as the foramen magnum. The basilar artery climbs along the brain stem and forms two posterior cerebral arteries. It’s these arteries that nourish the posterior portion of the cerebrum. Stroke affecting the basilar artery may result in dizziness, coma, headache, pinpoint pupils, quadriplegia (loss of movement in both arms and legs), and dysphagia (difficulty swallowing).
The superior cerebellar arteries branch from the basilar artery. Among the regions of the brain it supplies are the superior surface of the cerebellar hemispheres, most of the white matter in the cerebellum, and portions of the midbrain. The anterior inferior cerebellar artery branches from the basilar artery near the pons. Strokes that affect the superior cerebellar artery can cause ataxia, an inability to voluntarily coordinate muscle movements. Strokes that affect the anterior interior cerebellar artery can cause ataxia, sudden hearing loss, vertigo, facial paralysis, and Horner’s body syndrome (a condition of the sympathetic nervous system that results in drooping eyelid).
The anterior portion of the brain receives blood from the bilateral carotid arteries. The common carotid arteries pass through the neck along one side of the trachea. Just below the mandible, each of these arteries branches into the internal and external carotid arteries.
The internal carotid artery ascends the neck until it reaches the base of the neck and enters the brain. Once on the brain’s inferior surface, it splits into several branches. One branch supplies blood to the eye and associated structures. Damage to this artery from stroke can cause sensory loss, especially in the lower extremities, and mental confusion.
Importantly, the anterior and middle cerebral arteries provide blood to the cerebrum, and stroke affecting the middle cerebral artery can result in hemianopsia (loss of vision in half the visual field) and hemiparesis (weakness on one side of the body).
Strokes that affect the internal carotid artery result in hemianaesthesia (loss of sensation on one side of the face and on the opposite side of the body) and hemiplegia (partial or total paralysis of half the body). If the ophthalmic artery is affected, the patient may suffer from visual loss. If the dominant sphere is affected, he or she may experience difficulty comprehending and expressing language (aphasia). However, in some instances there may not be any symptoms. This can occur if the patent posterior communicating artery supplies a sufficient amount of circulation to that part of the carotid artery that lies in the cranium.
Left-brain stroke recovery focuses on the left half of the brain, which typically plays a more significant role in speaking ability than the right brain. (It should be noted that simplistic popular distinctions between the left brain and right brain are largely bogus). Aphasia is a common problem for people who have suffered a stroke on the left side of the brain, and patients with this condition may forget the right words in a given situation, speak in short, fragmented, or incomplete sentences, and have trouble comprehending conversations. They may also suffer from dyscalculia, a weakened ability to grasp mathematics, or apraxia, in which the performance of everyday tasks like putting on clothes is diminished. Some patients even struggle with amnesia and sudden changes in their emotional makeup.
Right-brain stroke recovery treats the side of the brain primarily associated with depth perception and visual-spatial functions. Patients who have suffered a stroke to the right half of the brain may be prone to ignore people or things on the left side of their bodies (hemispatial neglect), or even deny ownership of their left limbs. Anosognosia is a rare condition in which patients aren’t aware that they’ve been disabled in any way and may try to carry on as before, with sometimes disastrous results. Stroke victims may also suffer from reduced visual memory and trouble interpreting body language and non-verbal clues, and may not be able to register sarcasm. This, in turn, creates trouble in social situations.
Recovery from hemorrhagic stroke should begin immediately after stroke. A physical therapist may begin range-of-motion rehabilitative exercises in the hospital by moving a patient’s limb or having them move their own limb. Gradually a patient should return to sitting, standing, and other daily activities like bathing and dressing. Length of recovery time will vary from patient to patient.
Patients seeking recovery from stroke will find a range of minor and major stroke recovery treatments at the New York DNR. We use advanced virtual reality and computer technology to rehabilitate stroke victims by identifying brain injuries and allowing both patients and therapists to practice activities in a simulated environment that can’t be achieved in an ordinary clinical setting. At the New York DNR we use Computer-Assisted Rehabilitation Environment to treat post-stroke injuries. A sophisticated technology developed by the U. S. Army, CAREN uses force-plate and motion-capture technology to identify postural and alignment problems and restore locomotion and balance.