head inj ury

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  1. 1. INTRODUCTION: - Any injury that results in trauma to the scalp, skull, or brain can be classified as a head injury. The terms traumatic brain injury and head injury are often used interchangeably in medical literature. Unlike a broken bone where trauma to the body is obvious, head trauma can sometimes be obvious or discrete. In the case of an open head injury, the skull is cracked and broken by an object that makes contact with the brain, this leads to bleeding. Other obvious symptoms can be neurological in nature. The person may become sleepy, behave abnormally, lose consciousness, vomit, develop a severe headache, have mismatched pupil sizes, and/or be unable to move certain parts of the body. While these symptoms happen right after head injury occurs, many problems can develop later in life. Alzheimers disease, for example, is much more likely to develop in a person who has experienced a head injury. ANATOMY & PHYSIOLOGY:- :BRAIN: Brain in divided into 3 main components: cerebrum, brainstem & cerebellum. CEREBRUM Cerebrum is composed of left & right hemispheres. Both the hemispheres can be further divided into 4 major lobes: frontal, temporal, parietal & occipital. Lobes of cerebral hemispheres Functions Frontal Controls higher cognitive functions, memory retention, voluntary eye movements, voluntary motor movements, expressive speech in brocas area. Temporal lobe Contains wernickes area , which is responsible for receptive speech & for integration of somatic, visual & auditory data. Parietal lobe Controlling & interpreting spatial information Occipital lobe Processing of sight These divisions are useful to delineate the portions of neocortex (gray matter), which makes up the outer layer of cerebral hemispheres. Neurons in specific parts of the neocortex are essential for various highly complex &
  2. 2. sophisticated aspects of mental functioning such as language, memory & appreciation of visual spatial relationships. Basal ganglia are a group of paired structures located centrally in the cerebrum & midbrain, near lateral ventricles of both cerebral hemispheres. It controls & facilitates learned & automatic movements. Thalamus (part of diencephalon) is lying above the brain stem & below the basal ganglia. It is the major relay center for sensory & other afferent (i.e., cerebellar) inputs to the cerebral cortex. Hypothalamus is located just below the thalamus & slightly in front of the midbrain. It regulates the ANS & endocrine system. Limbic system located lateral to hypothalamus, near the inner surfaces of the cerebral hemispheres. It is concerned with emotion, aggression, feeding behaviour & sexual response. BRAINSTEM It includes midbrain, pons & medulla. Ascending & descending fibers pass through the brainstem going to & from the cerebrum & cerebellum. The cell bodies , or nuclei ,of cranial nerves iii to xii are in the brainstem. Reticular formation a diffusely arranged group of neurons & their axons that extends from the medulla to the thalamus & hypothalamus, is also located here. Its functions include relaying sensory information, influencing excitatory & inhibitory control of spinal motor neurons, & controlling vasomotor & respiratory activity. RAS , a part of the reticular formation , is the regulatory system for arousal. Medulla acts as respiratory, vasomotor & cardiac function regulatory center. Brainstem also contains centers for sneezing, coughing, hiccupping, vomiting, sucking & swallowing. CEREBELLUM Cerebellum located in the posterior part of the cranial fossa, along with the brainstem under the occipital lobe of cerebrum. Its function is maintain coordinate voluntary movement & to maintain trunk stability & equilibrium.
  3. 3. :PROTECTIVE STUCTURES: MENINGES It consists of 3 protective layers: dura, arachnoid & pia mater. The flax cerebri is a fold of the dura mater , that separates both hemispheres & preventing expansion of brain tissue. SKULL The three bone layers of the skull. The human skull is anatomically divided into two parts: the neurocranium, formed by eight cranial bones that houses and protect the brainand the facial skeleton (viscerocranium) composed of fourteen bones, not including the three ossicles of the inner ear. The term skull fracture typically means fractures to the neurocranium, while fractures of the facial portion of the skull are facial fractures, or if the jaw is fractured, a mandibular fracture. NEUROCRANIUM: The eight cranial bones are separated by sutures : one frontal bone, two parietal bones, two temporal bones, one occipital bone, one sphenoid bone, and one ethmoid bone. The bones of the skull are in three layers: the hard compact layer of the external table (lamina externa), the dipole (a spongy layer of red bone
  4. 4. marrow in the middle, and the compact layer of the inner table (Lamina interna). SCALP The scalp is the anatomical area bordered by the face anteriorly and the neck to the sides and posteriorly. Structure: The scalp is usually described as having five layers, which can conveniently be remembered as a mnemonic. S: The skin on the head from which head hair grows. It contains numerous sebaeceous glands and hair follicles. C: Connective tissue. A dense subcutaneous layer of fat and fibrous tissue that lies beneath the skin, containing the nerves and vessels of the scalp. A: The aponeurosis called epicranial aponeurosis (or galea aponeurotica) is the next layer. It is a tough layer of dense fibrous tissue which runs from the frontalis muscle anteriorly to the occipitalis posteriorly. L: The loose areolar connective tissue layer provides an easy plane of separation between the upper three layers and the pericranium. This layer is sometimes referred to as the "danger zone" because of the ease by which infectious agents can spread through it to emissary veins which then drain into the cranium. The loose areolar tissue in this layer is made up of random collagen I bundles, collagen III. It will also be rich in glycosaminoglycans (GAGs) and will be constituted of more matrix than fibers. P: The pericranium is the periosteum of the skull bones and provides nutrition to the bone and the capacity for repair. It may be lifted from the bone to allow removal of bone windows (craniotomy). BLOOD SUPPLY OF BRAIN CEREBRAL CIRCULATION Cerebral circulation or blood supply of the brain arises from the internal carotid arteries(anterior circulation) and the vertebral arteries(posterior circulation). Each internal carotid artery supplies the ipsilateral hemisphere, whereas the basilar artery form by the junction of the two vertebral arteries, supplies structures within the posterior fossa (cerebellum and brain
  5. 5. stem).The circle of Wills arise from the basilar artery and the two internal carotid arteries. This vascular circle may act as a safety valve when differential pressures are present in these arteries. It also may function as an anstomotic pathway when occlusion of a major artery on one side of the brain occurs. In general, the two anterior cerebral arteries supply the medial and anterior portion of the frontal lobes. The two middle cerebral arteries supply the outer portions of the frontal, partial, and superior temporal lobes. The two posterior cerebral arteries supply the medial portions of the occipital and inferior temporal lobes. Venous blood drain from the brain through the dural sinuses, which form channels that drain into the two jugular veins. SCALP CIRCULATION The blood supply of the scalp is via five pairs of arteries, three from the external carotid (superficial temporal artery, occipital artery & posterior auricular artery) and two from the internal carotid( supratrochlear artery & supraorbital artery ). Note: The walls of the blood vessels are firmly attached to the fibrous tissue of the superficial fascial layer, hence cut ends of vessels here do not readily retract; Even a small scalp wound may bleed profusely. INNERVATION OF SCALP The innervation of scalp can be remembered using the mnemonic, "Z- GLASS" for, Zygomaticotemporal nerve, Greater occipital nerve,Lesser occipital nerve, Auriculotemporal nerve, Supratrochlear nerve and Supraorbital nerve. LYMPHATIC Occipital and posterior auricular nodes, parotid nodes, submandibular and deep cervical nodes . EPIDEMIOLOGY IN INDIA:- Traumatic brain injuries (TBIs) are a leading cause of morbidity, mortality, disability and socioeconomic losses in India and other developing countries. It is estimated that nearly 1.5 to 2 million persons are injured and 1 million succumb to death every year in India. Road traffic injuries are the leading cause (60%) of TBIs followed by falls (20%-25%) and violence (10%). Alcohol involvement is known to be present among 15%-20% of TBIs at the time of injury. The rehabilitation needs of brain injured persons are significantly high and increasing from year to year. India and other developing countries
  6. 6. face the major challenges of prevention, pre-hospital care and rehabilitation in their rapidly changing environments to reduce the burden of TBIs. CAUSES:- Motor vehicle traffic collisions ,Home and occupational accidents, falls, Assaults. CLASSIFICATION:- There are many ways that head injuries can be classified. The three most useful descriptions are: Severity Morphology Mechanism of injury Time of showing impact or consequences Classification as per Severity 1. Severity based on Glassgow Coma Scale Best Eye Response. (4) No eye opening. Eye opening to pain. Eye opening to verbal command. Eyes open spontaneously. Best Verbal Response. (5) No verbal response Incomprehensible sounds. Inappropriate words. Confused Orientated Best Motor Response. (6) No motor response. Extension to pain. Flexion to pain. Withdrawal from pain. Localising pain. Obeys Comm