Head Injuries (I) Dr. Asmaa Fady PhD., MSC., M.B, B.Ch

Learning objectives: By the end of the lecture, the student should know: Forensic anatomy of scalp, skull, meninges and brain. Medico-legal importance of scalp injuries Differences between traumatic & pathological meningitis Types of skull fractures, under each one we have to know, the causative instruments, mechanism of infliction, characters, subtypes, fracture dating and dangers. Types of intracranial hemorrhages, under each one we have to know the mechanism of infliction, subtypes. اسم ورقم المقرر – Course Name and No. 7/5/2019

Scalp Forensic Anatomy Anatomy: Scalp consists of several layers: hairy skin, the subcutaneous fat and connective tissue layer, the galea aponeurosis, a thin layer of connective tissue and periosteum of the skull.

Medicolegal Importance of Scalp Injuries 1- The amount of bleeding is not the clue for the severity of the injury as the scalp is rich in blood supply. 2- There is minimal liability for sepsis but if occurred this would be dangerous [intracranial spread of infection]. 3- Contused wounds may simulate cut wounds [how to differentiate?]. 4- It is important to differentiate between different types of meningitis that will help in the allegation that head injury leads to meningitis.

Differences between traumatic and pathological meningitis   Traumatic Meningococcal Otitis media - History Trauma Sore throat, epidemic Middle ear disease - Evidence of trauma, scalp infection Present Absent - Skull affection May be fractured Normal Temporal necrosis, mastoiditis -Meningeal pus Under lying the wound Generalized-basal Temporal - Bacteriology Similar to that of the scalp Similar to ear organism. 7/5/2019 اسم ورقم المقرر – Course Name and No.

Factors Governing Skull Fractures 1- Force (momentum) i.e. kinetic energy; it is related to mass and velocity. 2- Striking surface area: e.g. head of hammer has small striking surface area while stick has large striking surface area. 3- Position of the head: whether supported or not. 4- Site of the blow: the thinnest areas of the skull are the parieto- temporal bone , the lateral frontal bone and lateral occipital zones. 5- Elasticity of the bone: fractures are more severe in old age (why?)  

Skull fractures caused by blunt instrument SSA Striking Surface Area Large SSA LOW momentum Fissure fracture HIGH momentum Depressed Comminuted fracture localized SSA Localized depressed MODERATE momentum Localized depressed with partial comminution Localized depressed comminuted Firearm fracture of the skull: loss of substance caused by blunt instrument with small striking surface area & very high momentum "bullet".

Skull fractures caused by sharp instruments According to direction tangential Chipped fr vertical According to force cut light Cut comminuted Heavy

Skull Fractures: I) fracture vault of skull. A-Skull fractures due to blunt instruments. Fissure – depressed (localized or not) – comminuted B- Skull fractures due to sharp instruments chipped - cut - cut comminuted caused by sharp instrument passing tangentially

1-Fissure fracture (linear fracture). Characters: 1. Blunt instrument with wide striking surface area and low momentum. 2. It starts at the point of impact. 3. The fissure may bifurcate and may run into sutures of the skull. (Diastatic fracture). 4. Multiple blows may produce multiple fissures. اسم ورقم المقرر – Course Name and No. 7/5/2019

Linear fissure fracture extending to the sutures

Types of fissure fracture Polar fracture: It extends parallel to the line of force and perpendicular to the direction of trauma. Ring fracture: In case of falling from a height on the breech, the head is stationary and the vertebral column is pushed upwards, causing fissure fracture around the foramen magnum. In cases of "upper cut" in boxers, where the chin is pushed upwards, the head of the mandible is pushed hard against the glenoid cavity leading to a fissured fracture around it. Thermal fracture: Fissure occurring in case of severe burn of the head due to evaporation of water from outer before inner table Hinge fracture: Fissure passing across the base separating it into two halves as in road traffic accidents. Diastatic fracture: Fissure pass through skull sutures اسم ورقم المقرر – Course Name and No. 7/5/2019

2- Depressed fracture Subtypes of depressed fracture a- Depressed localized fractures. Cause: due to a heavy blunt object having a localized striking surface. e.g. head of a hammer. Shape: It takes the shape & size of striking surface of the causal object (rounded, square, triangular, etc …..). b- Depressed comminuted fracture: Cause: It occurs due to a blow with heavy blunt object having a wide striking surface area and high momentum e.g. car accidents, fall from high and block of wood. Shape: There is a wide depression of bone comminuted into numerous fragments. In this condition the fragments of bone must be removed by a lion forceps. They are usually accompanied with brain injury. اسم ورقم المقرر – Course Name and No. 7/5/2019

Depressed localized fracture Depressed localized fracture with complete comminution Depressed localized fracture with partial comminution

Comminuted Fracture of the skull with evident bone loss       Comminuted Fracture of the skull with evident bone loss

B) Skull fractures caused by sharp instruments A- Sharp and heavy instruments (e.g. the blade of an axe, cleaver or chisel). 1- Cut comminuted: The fracture has regular, straight sharply cut edges with bone comminution B- Sharp and light instrument e.g. knife 1- Cut fracture: with regular, straight, sharply cut edges. 2- Chipped fracture: Caused by the blade passing tangentially involving only the outer table, it occurs at mastoid process, nuchal region, parietal eminences or frontal bone. اسم ورقم المقرر – Course Name and No. 7/5/2019

Injuries caused by sharp instruments: cut fracture chipped fracture

II) - Fracture Base of the Skull Usually fissure fractures More common than fractures of the vault because the base is less elastic and is weakened by the presence of multiple foramina.

Types and clinical presentation of Fracture Base of the Skull A) Fracture anterior fossa: It presents by black eye, subconjunctival hemorrhage and rhinorrhea & nasal bleeding (DD. Of black eye). B) Fracture Middle fossa: It presents by otorrhea and bleeding from the ear. C) Fracture posterior fossa: It presents by nuchal stiffness due to escape of blood and CSF into the neck tissues.

Healing of Skull Fractures Fissure fracture Gluing of the edges: one week. Smoothening of the edges: 2-3 weeks. Complete closure: 3-4 months. Other types of fractures: Smothering of the edges: 3weeks. Filling of the bony gap by a fibrous membrane in 6-12 months This membranous area is a permanent infirmity being (Long term Complications; Jacksonian Epilepsy)

Injuries to Meninges 1- Extradural hemorrhage (EDH) This hemorrhage results from trauma leading to fissure fracture or bone spicules that injure the blood vessels. It never occurs pathologically Middle meningeal artery or its branches [common and rapid accumulation].

Extradural hemorrhage Mechanism A blow to the temple leading to fracture of the temporal bone causing tear of the middle meningeal artery. Leakage of the high pressure arterial blood strips the dura off the inner skull table forming hematoma.

Injuries to Meninges 2-Subdural haemorrhage [SDH] More common than extradural hemorrhage, it results from trauma to the head and may occur without skull fracture or pathological conditions. Types A- Acute: due to trauma to the head leading to tear of the vessels in subdural space. B- Chronic: It is initiated by minor trivial repeated trauma to the head patients predisposed by (e.g. Atherosclerosis, blood diseases… etc).

Subdural hemorrhage

Injuries to Meninges 3- Subarachnoid hemorrhage (SAH). A- Traumatic (Due mainly to trauma to the head): It is uncommon to be alone, so, it is associated with all penetrating injures of the brain as will as many blunt injuries that give rise to extradural & subdural hemorrhages. B- Pathological More common than traumatic. Occurs due to rupture Berry Aneurysm Congenital Aneurysm due to congenital absent of the media in one of the arteries in circle of Willis, it is common in young age. Leading cause of sudden death in young adults.

Subarachnoid hemorrhage

اسم ورقم المقرر – Course Name and No. 7/5/2019