Penetrating head injuries caused by a new weapon, the side dome
Sviri, Gil Ephraim
The “side dome” is a mix of high and low explosives with a multitude of small metal balls molded within a specially designed half-sphere that directs the explosion wave and the projectiles in one direction to augment the harm. This weapon, originally designed by guerrilla and terrorist groups, is now used by regular armies. This report presents one craniocervical and eight cranial injuries caused by this new weapon and discusses the cases’ various clinical features, the paucity of intracerebral cavitation damage along the missile track, the need for only minimally aggressive surgery, and the relatively favorable outcome. In all cases, the helmet offered good protection and the entry of the projectiles was just below its rim in an upward direction.
Introduction
During the last decade, there has been widespread use of a new weapon: the side dome.” It was first developed by guerrilla and terrorist groups and is now used by regular armies. In its initial primitive form, the side dome consisted of a concave metal sheet filled with explosives and various metal fragments activated by a trip wire or by remote control. It was designed to maim by both a shock wave and multiple injuries at close range. This weapon proved to be effective. and consequently it was adopted and manufactured by regular armies. Today, a mix of high and low explosives and a multitude of metal balls are molded within a specially designed half-sphere (hence the name side dome) that directs the explosion wave and the projectiles in one direction to augment the harm. We present and discuss the various clinical features of one craniocervical and eight cranial injuries caused by this new weapon. Despite the injured soldiers’ proximity to the explosion site, the helmet and the shield vest offered, in most instances, adequate protection, and the majority of the penetrating injuries were to the nonsheltered extremities or just below the rim of the helmet.
Patients The patients were soldiers of the various forces operating in the arena of southern Lebanon: Israel Defense Forces, Southern Lebanon Army, and United Nations observers. Israel Defense
Forces Medical Corps personnel provided initial resuscitation and treatment. All but one of the wounded (patient 4) were evacuated directly to Rambam [Maimonides) Medical Center (RMC) by helicopter (flight time of approximately 30 minutes).
Patient 1
Thirty minutes after the explosion of a side dome, this person was found in a coma with a dilated right pupil. He was rapidly intubated, ventilated, stabilized with intravenous fluids, and evacuated to RMC. Entry wounds were found behind the left ear and in the left shoulder, elbow, and leg. Brain computed tomography (CT) revealed an entry site through the left mastoid bone overlying contused brain with several bone splinters. The track of a metal ball passing through the lateral ventricles had caused intraventricular hemorrhage. The projectile was located in the right frontal lobe after ricocheting from the right parietal bone, stirring acute subdural hematoma. Injuries to the left extremities proved to be superficial. The subdural hematoma was evacuated by right frontoparietal craniotomy. Left temporal craniectomy enabled debridement of necrotic brain tissue and hemostasis at the entry site. The patient died 4 days later after developing uncontrolled intracranial pressure as a result of multiple expanding hematomas located along the projectile track.
Patient 2
Projectiles of a side dome hit a 22-year-old soldier standing in an armored car. He was immediately rendered unconscious with no spontaneous breathing, and the emergency medical team promptly intubated and evacuated him to RMC. On admission, he was unconscious, with no response to painful stimuli below the neck: quadriplegia was evident. He was hemodynamically unstable, with hypotension and bradycardia. There were multiple entry wounds in the right axilla and shoulder and two in the right cervical region. Five balls were located at the right upper chest. CT disclosed two metal spheres in the cervical soft tissues, air in the upper spinal canal. and epidural hematoma at the level of Cl-4. Blood filled the fourth ventricle. The patient was treated with intravenous fluids. phenylephrine, and a high dose of methylprednisolone. The epidural hematoma was evacuated. Two days later. he regained consciousness. but he remains quadriplegic and has required mechanical ventilation for 2 years.
Patient 3
A 23-year-old officer triggered the explosion of a side dome while leading his platoon. Rendered unconscious with multiple penetrating injuries, he was transported to RMC ventilated and hemodynamically stable. Examination disclosed small bowel lacerations, compound comminuted fractures of the left distal femur and patella, and a left eye severed by an intraocular projectile. Brain CT revealed that a metal ball had entered just above the left orbit, traversed to the right hemisphere. and ricocheted to the occipital pole, causing acute right subdural hematoma (Fig. 1). The hematoma was evacuated and the other injuries were treated. The left eye had to be enucleated. Intracranial pressure remained within normal values. Four days after the injury, the patient started to regain consciousness. He complained of loss of vision in the right eye; however, the pupil reacted well to light. Vision returned within 1 week, at first to the temporal field, and about 10 days later to the nasal field. There was left hemiparesis that cleared within 6 months. At follow-up examination 22 months later, the patient reported recovery from all injuries apart from the loss of his left eye. Neurological recovery was complete without any overt sign of cognitive deficit. A low, very small nasal field defect could be detected. This defect did not hinder useful vision.
Patient 4
After the explosion of a side dome, this 21-year-old soldier was found to have some oozing from a little wound just below the rim of his helmet in the posterior temporal region. He was conscious and talked. Considered only lightly wounded, he was transferred to a secondary center. Two hours later, he became confused and drowsy and was transported, ventilated and under the influence of muscle relaxants, to RMC. CT of the head disclosed that a metal ball had traversed from the lower left temporal region to the vault of the right parietal lobe, producing contusion and intracerebral hematoma with mass effect visible at the entry site (Fig. 2). The entry wound was debrided and the hematoma was evacuated. The postoperative course was uneventful, and intracranial pressure remained stable. More than 2 years after the injury, the patient is doing well at college, albeit with minimal cognitive deficit.
Patient 5
Various metal fragments packed into an improvised side dome injured a 21-year-old soldier. A few projectiles damaged his right groin, and the emergency medical team was busy controlling the hemorrhage and stabilizing blood pressure. Upon arrival at RMC, the patient was conscious but complained of blindness. The pupils reaction to light was brisk, but there was no reaction to threatening movements. A small entry wound was seen above the left eyebrow just below the rim of the helmet. Brain CT revealed a small metal fragment that had entered the forehead, traversed the hemisphere, and was lodged in the occipital pole after recoiling from the parietal bone. The femoral vessels were repaired; only minimal debridement was required for the head wound. Five days after the injury, the scope of blindness had reduced to hemianopia. One month later, the visual field defect was reduced further to right homonymous quadrantanopia. The visual fields did not change in the ensuing 5 months. A minimal cognitive deficit does not prevent the patient from pursuing a career and gaining full employment as a systems analyst.
Patient 6
This 26-year-old battalion physician was injured in an explosion of a side dome. He did not lose consciousness, but he was confused and complained that he could not see. The only external injury was a left temporal small entry wound just above the zygomatic arch. He was quiet, as if stunned, and continued to complain of blindness. Both pupils reacted briskly to light, but there was no reaction to threatening movements. Responses to simple questions were correct, but mild motor aphasia was evident. No motor deficit was found. CT revealed minute bone fragments adjacent to the entry site in the left temporal region and the bloodstained track of a metal ball that had lodged in the left occipital lobe adjacent to the falx (Fig. 3). Surgery was limited to superficial debridement. As the patient’s confusion cleared, the range of blindness shrunk to right homonymous hemianopia, which in turn was reduced to less than superior quadrantanopia within 2 weeks. Five months later, the patient still has minimal anomia.
Patient 7
The explosion of a side dome maimed the lower limbs of this 22-year-old soldier and caused massive blood loss from the groin: there was no loss of consciousness. The emergency medical team, absorbed in controlling the hemorrhage, left the other injuries to be evaluated at RMC. After surgical repair of the patient’s femoral arteries and the application of an external fixator to the fractured bones, the patient awoke complaining of an excruciating headache. The skull radiograph resembled an air ventriculography (Fig. 4. A metal sphere had entered the corner of the frontal sinus, injured the posterior wall, lacerated the dura, and made its exit via the opposite corner of the sinus. The dura was repaired through endoscopic exploration of the sinus. Recovery was uneventful.
Patient 8
Several projectiles of a side dome injured this 32-year-old person in the head. The armor of his car protected the rest of his body. He was rendered unconscious immediately and exhibited very shallow and irregular breathing. Resuscitation and evacuation to RMC were prompt. He was unconscious on admission, showing no response to deep pain; quadriplegia was evident. He had pinpoint pupils with skewed deviation of the eyes and was hemodynamically unstable, with hypotension and bradycardia. Vasopressors were required to establish proper circulation. Several wounds were visible in the face and scalp. CT disclosed that only one metal fragment had penetrated the skull: after traversing the inferior aspect of the left temporal lobe, it was lodged just anterior to the brain stem. There were massive subarachnoid and intraventricular hemorrhages (Fig. 5). Two days later, basilar artery vasospasm was diagnosed based on transcranial Doppler findings. After 10 days, the blood flow velocities returned to normal values. The patient regained consciousness and from then on made a slow but constant recovery. Six weeks after the injury, exhibiting minimal spastic quadriparesis, the patient was fit to be transferred to a rehabilitation center. Four months later, he could walk unaided, and fine skilled movements of the hands are slowly returning.
Patient 9
The explosion of a side dome activated by remote control injured a 22-year-old patrol sergeant. There was profuse bleeding from the right groin and thigh; blood was trickling from a little wound just below the rim of the helmet, above the right eye. There was no loss of consciousness, but left hemiparesis was noted. The hemorrhage was controlled and blood pressure was stabilized. At RMC, after the repair of the injured vessels of the groin, CT of the head disclosed the track of a metal ball that had penetrated just above the right eyebrow, ascended to the vault, and ricocheted to the depth of the right parietal lobe. Only very few minute bone splinters were seen at the entrance site, so minimal debridement of the entry wound was sufficient. The patient had an uneventful recovery, and at 22 months after the injury he has moderate cognitive deficit. There are no lateralizing signs.
Discussion
Throughout history, conflicts and disputes have been accompanied by guerrilla warfare and terrorist activities that add novel methods and means to the hostilities. These developments are later incorporated into the arsenal of regular armed forces. The side dome, at first a makeshift terrorist or guerrilla weapon, is used and manufactured today by regular armies. It is used mainly as a booby trap to maim and cause havoc in scouting patrols or convoys. The damaging potential is related to the distance between the target and the dome. RMC experience shows that among the patients wounded by the side dome there was no instance of helmet or shield vest penetration. Lethal injuries, occurring in most cases at very close range to the explosion site, were caused by either the effects of the blast or direct damage to major blood vessels in the groin, axilla. or neck. In such cases, death occurred before the wounded reached RMC.
Low-energy projectiles were the cause of injury in our patients, although high-velocity projectiles are customarily considered the cause of military firearms injuries. This latter assessment should be reexamined. because it is the impact energy, rather than the explosion velocity, that is consequential. Thirty-six years ago, Freytag.1 in a study that to this day remains singular and frequently quoted, analyzed the various courses taken by low-energy, penetrating bullets. She drew attention to the absence of cavitation. the large hematomas, and the exit wounds seen in penetrating injuries caused by projectiles of high impact energy2,3′ The possibility that the bullet may ricochet from the skull or even the falx or the tentorium was another feature of injuries caused by low-energy projectiles.
The absence of a muzzle causes a rapid decline in the velocity of side dome projectiles. In this series. the helmet offered good protection, and the projectiles pierced the skull only from below, just at the helmet’s rim. This mode of penetration through the skull base has existed since Biblical times,4 and its role in modern warfare was highlighted in a survey of the Israeli early wartime neurosurgical experience in Lebanon (1982-1985).5 This upward course of the projectile was seen in six of our nine patients (Fig. 2). It seems that better protection of the cranial base and the cervical region might have prevented some of the injuries described above. However, the decision to offer a more protective, low-reaching helmet and a higher vest is not purely a medical one; in military considerations, the protection of the soldier is often secondary to his or her efficiency and performance in combat.
There was one death in this series. Here was a deadly combination of several aggravating factors: the projectile’s transventricular trajectory, which is notorious for unfavorable outcome23: the long time lapse between injury and resuscitation, which added hypoxic insult to cerebral injury; and the brain’s compression from an acute subdural hematoma. A recent report on a series of critically head-injured soldiers from the Lebanese theater of war demonstrated that immediate intensive resuscitation is of the utmost importance.6
The tragic outcome of patient 2 was caused by direct impact to the spinal cord, which caused immediate cessation of function; the chances of recovery in such cases are practically nil. In addition, a considerable blow must have been transmitted to the medulla as well, as was made evident by the blood-filled fourth ventricle.
The patients in our series were operated on according to the guidelines of minimally aggressive surgery.7 No complications were encountered during the follow-up period.
The main features observed in this series were: an ascending track of the projectile from the skull base to higher levels (patients 1, 4, 5, 6, 8, and 9); a long intracerebral track of the missile, often without major neurological impairment (patients 1, 3, 4, 5 and 9): a very small amount of intracranial bone splinters at the metal balls’ entry site compared with the amounts found in injuries caused by missiles of high muzzle velocity (patients 1, 3, 4, 5, and 6); intracranial ricocheting of the metal ball (patients 1, 3, 5, and 9); the formation of acute subdural or intracerebral hematomas at the point of intracranial impact (patients 1, 3, and 4); and the immediate life-threatening injury was hemorrhagic shock from lower limb injuries, especially at the groin (patients 5, 7. and 9).
The course of visual symptoms observed in patients 3, 5, and 6 is especially interesting. Despite the involvement of only one occipital lobe. these patients initially complained of total blindness that within several days turned out to be homonymous hemianopia: this was further minimized to quadrantanopia in patient 5, whereas in patients 3 and 6 the visual field was restored almost completely. It may be that in addition to the injured occipital lobe, the contralateral lobe also sustained an impact, transmitted through the falx, that caused concussion and transient loss of function that presented as blindness. The classic studies investigating the effects of penetrating head injuries on the visual system are based on examinations carried out long after injury.s-” We could not find reports concerning the dynamics of recovery from penetrating injury to the occipital lobe. It is tempting to suggest that we witnessed an instance of von Monakow’s diaschisis and its resolution.l2’13
Armed conflicts are ceaselessly incited, and new weapons and military technologies do not remain confined to restricted regions. There is unavoidable harmful spillage even into civilian life. The damage inflicted by these weapons should be recognized by those assigned to treat injuries from firearms.
Acknowledgment
This study was supported by the generosity of the Joseph Szydlowsky Foundation. The authors are greatly indebted to the commitment of Mrs. S. Stem.
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The Center for Treatment and Applied Research in Head Injuries. the Department of Neurosurgery. Rambam (Maimonides) Medical Center, and B. Rappaport Faculty of Medicine. The Technion Israel Institute of Technology. Haifa, Israel. This manuscript was received for review in August 1998. The revised manuscript was accepted for publication in December 1998. Reprint & Copyright G by Association of Military Surgeons of U.S., 1999.
Copyright Association of Military Surgeons of the United States Oct 1999
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