HEAD INJURIES By Dr. Naveen

Brief In criminal and accidental injuries, the

head is especially vulnerable and an understanding of the mechanism of head injuries is essential in forensic medicine. The head is the heaviest part of the body relative to its size and is poised on the spine in a rather unstable position, being mainly secured by the tone of the neck muscles.

Though the brain is enclosed within a strong bony cranium, distortion and transmitted forces can cause a variety of lesions within the skull, both to blood vessels and neural tissue. It is most convenient to describe head injuries in sequence from the outside to the interior.

Scalp injuries The scalp consists of hairy skin over subcuta

neous tissue, beneath which is the fibrous membrane of the aponeurosis or galea,which is really the tendon of the vestigial epicranial muscles. Underlying this is a thin layer of connective tissue, then the periosteum of the outer table of the skull. The scalp is very vascular and bleeds profusely on damage. It can continue to bleed after death, especially if the head is in a dependent position.

The scalp is often lacerated by impact, as the underlying rigid skull acts as an anvil, against which the scalp can be crushed, Even a blunt impact, from a blow from an instrument or a fall against a hard object, can cause a sharply defined split. This may be mistaken for an incised wound from a cutting instrument, though close inspection of the wound edges will show a narrow zone of crushing and bruising with hairs and fibrous strands crossing the depths of the wound.

When injured by a blunt impact, the scalp often swells markedly, due to oedema and haematoma collecting either above or below the aponeurosis.

A severe glancing or tangential force, either from a blow or especially from a rotating wheel in traffic accidents, may tear off a large flap of scalp, exposing the skull. This may also occur when long hair is entangled in machinery in industrial accidents.

Injury to the bones of the head -Fractures of skull –

Fracture of the skull bones may be simple or compound . However , irrespective of whether closed or open , the fractures of the skull bones may may be of the following types -

Fissures fracture – These are linear or thread like fractures running in a line , straight or curved . A fissured fracture may be continuous over one or two or more bones . Fissured fractures are caused due to impact with hard , tough and flat surface , This type of fracture is often the result of a fall on the ground or after being knocked down on the ground by a vehicle .

Comminuted fracture – When a part of the skull bone cracks into pieces , it is termed comminuted fracture . This occurs often in radiating fashion , with the center being at the site of the impact and fissures radiating from that point in more than one direction , along the direction of radiation of the force of impact .

砖击颅底骨折

砖击左颞骨折

颅底粉碎性骨折

凹陷性骨折—凹陷明显处

船挤

压凹陷性骨折—

凹陷明显

处

二次打

击

Depressed comminuted fracture – This occurs due to forceful localised impact causing multiple linear fractures radiating from the site of impact with depression of the site of impact where the bone breaks into pieces .

Depressed comminuted fractures are called ‘Fracture Ala Signature’ , because , like the signature of a person the weapon which has caused the fracture may leave its impression on the fracture from which the shape and size of the striking part of the weapon can be known .

钉耙打

击

粉碎性骨折—碎片最多处

Thus the depression may be circular , if the striking surface is circular , it will be elongated if the object of impact was an elongated one . This type of fracture may occur in case of primary impact by a vehicle .

In such a case , from the size and shape of the fracture , part of the vehicle striking the head can be known . In homicidal cases , if a hammer has been used , then that also can be guessed from the shape and size of the depressed fracture .

Pond fractureHappening in infant skull.Where the bones are not yet fully

calcified and hence are soft and yield on application of force. Thus, at the site of impact of the force there is a depression but there is no cracking anywhere or there will be very small or minor cracking.

Suture fracture or sutural separationWhen the impact is over an wider area

of the head, there may be separation of the bones at the sutures. In case of elderly subjects where partial calcification of the sutures have occurred there may be fracture in the line of the sutural obliteration, if similar impact is applied on the head over an wider area.

Contre-coup fracture When the impact is over the occipital region, then the

force will be directed anteriorly. In case of its path the force causes vibration. Wherever the force passes through a thin and weak bone in its path, it may cause fracture of the bone.THus , in a case of reasonably heavy impact on the occipital bone,there may not be any fracture at the site of impact due to toughness of the occipital bone,but the force , when passes anteriorly causes frature of the thin orbital plates of the frontal bone, Mechanism of contre coup injury to brain is totally different.

Fracture on the anterior fossa Fracture at the anterior fossa of the base of th

e skull occurs mostly due to an impact in front of the head. Fissured fracture of the orbital plates of the frontal bone may occur due to impact over the occipital bone posteriorly. If the anterior fossa fracture extends upto the sinuses, then there is a chance that this will lead to infection inside the cranial cavity. It is often the extension of fracture of the middle fossa

Fracture of the middle fossaA linear fracture may extend across the

middle fossa including the pituitary fossa. Such fracture commonly occurs due to heavy side by side compression. Middle fossa fracture may extend to the anterior fossa.

Posterior fossa fracture Occur due to the direct impact over the

posterior part of the skull.

Fracture of the mandibleDue to direct impact. Vertical fractures

by the sides of premolars are the most common ones.

Fracture of the maxilla It occurs due to direct impact, when the

face of a person directly gets an impact with some hard structure like a wall or a tree, as usually happens in motor-cyclists, colliding against a wall or a tree when he is forcefully thrown forward.

INTRA-CRANIAL HAEMORRHAGES - Haemorrhages inside the skull cavity may occ

ur at different levels and at different sites . Intracranial haemorrhages may be traumatic , or atraumatic (pathological) . When traumatic in origin , there may be accompanying fracture of the skull bone . But in many cases , intracranial haemorrhages may be without fracture of the skull bone , though traumatic in origin.

According to the levels , intra-cranial haemorrhages may be of the following types –1. Extradural or epidural 2. Subdural 3. Subarachnoid 4. Intra-cerebral

Extradural haemorrhage – In most circumstances ,haemorrhage at this level is traumatic in nature . The vessels involved in the trauma are middle meningeal artery (most common due to the peculiar site of involvement ) and dural venous sinuses .

The accumulation of blood occurs most commonly in the temporal region , with fracture of petrous part of the temporal bone .The blood which accumulates causes compression of the brain substance and exerts pressure effects .

The blood is not encapsulated and may not be absorbed for over a long period . Thus chronic cases of extradural haemorrhage are seen . Chronic extradural haemorrhage is more common on the posterior fossa .

Extradural haemorrhage may occasionally occur due to blood dyscrasias In children . Fatality is due to compression effect and timely evacuation of the blood may save the life of the patient .

Subdural haemorrhage is almost always traumatic in nature . Traumatic subdural haemorrhage occurs due to laceration or rupture of the superior longitudinal sinus near the debouchment with superior cerebral vein of the side of impact .

This causes PRIMARY SUBDURAL HAEMORRHAGE when he accumulation of the blood usually occurs at the dorsolateral aspects of the upper surface of either or either or both hemispheres.

SECONDARY SUBDURAL HAEMORRHAGE occurs due to injury (laceration) of the brain substance when the primary site of the haemorrhage is in the brain substance and the extravasated blood accumulates in the subdural space.

. Evacuation of the primary subdural haemorrhage gives good prognosis .

Secondary subdural haemorrhage may cause accumulation of blood on the medial aspects of the occipital lobes or in the midbrain above the pons .Secondary subdural haemorrhage may get encapsulated to form a cyst ,(pachymeningitis haemorrhagica interna). Prognosis of exploration of the secondary subdural haemorrhage is generally grave.

In the general conception ,subdural haemorrhage is more common phenomenon in young adults . when due to trauma ,it involves victims of almost all ages and in many cases almost the whole of the surface of the brain .Even the base may have accumulation of the blood .

Subarachnoid haemorrhage –May be traumatic or natural .When traumatic it may be primary or secondary .In primary subarachnoid haemorrhage the vessels of the circle of Willis ,anterior cerebral artery and less commonly the posterior cerebral artery are involved .

砖击致蛛膜下出血

砖击致蛛膜下出血

割耳后跳楼致额顶挫伤伴蛛膜下出血

通奸女被夫兄

杀

被追捕过程中，硬膜外血肿，蛛膜下出血

Young and elderly adults are the usual victims and it is assumed that even in traumatic subarachnoid haemorrhage trauma may actually be a minor factor in causing the haemorrhage. More important is the condition of the vessels .

Secondary subarachnoid haemorrhage occurs due to contusion and laceration of the cerebrum, the blood defusing to the undersurface of the arachnoid matter.

Natural subarachnoid haemorrhage is primarily due to degenerative changes of the vessels in elderly persons or due to rupture of congenital aneurysm in the young ,which usually occurs in small amount ,mostly near the base of the brain .

CEREBRAL CONCUSSION This being a sequelae of trauma is a m

ore complicated condition of brain structure and function than the term suggest . Literally , cerebral concussion means a ‘jar’ or ‘shock’ to the brain . Though that is what actually happens in cerebral concussion ,there are something more to consider .

陈旧性挫伤

Its pathological and legal status have been questioned in many occasions . Some claim that ,it is a condition which essentially is a sort of shock neurosis without any real pathology or damage to the brain and the ‘cause’ of the individual himself alone ,which should not be linked with any circumstance of assault or accident.

During post-mortem examination of these cases ,no gross or microscopic pathology could be detected in many of these cases .

The most constant post-concussional features are headache ,dizziness and nervousness though there may be other features depending on the extent of internal pathology .

During autopsy in many cases ,cerebral contusion ,oedema or minute haemorrhagic spots may be noticed macroscopically and changes in the nuclei of the nerve cells may be observed by microscopic examination .

Cerebral concussion is more commonly complained of in impacts received on the brain due to sudden deceleration of the moving head than in an impact received by a static head .

In cerebral concussion , there may or may not be any morphological change of the brain .Though the condition may have some functional element in it ,the individual should not be made responsible outright ,in spite of the accepted fact that the condition may be feigned for extracting certain benefit from a circumstance of accident or assault

割耳后跳楼致额顶挫伤伴蛛膜下出血