Disability Skills 1:
Skull Trephination
Although uncommon, acute epidural hematoma injuries are important injuries because they are reversible when they are managed quickly. They also occur mainly in teenagers and young adults in the prime of life. An important point is that the brain under this hematoma is usually normal, as opposed to the frequently severely injured brain beneath a subdural hematoma.
In many rural hospitals, CT scanning is readily available. If so, a quick CT scan is of great help. It identifies the side of the head where the hematoma is located and also shows if the hematoma is clotted or only partially so. Pure clot appears all white, while fresh blood is black. Partial clotting is the usual finding, signifying active bleeding and a hematoma that can be decompressed through a small hole. It also distinguishes between a subdural and an epidural. A “walk, talk, and deteriorate” presentation usually signifies epidural hematoma, but subdural hematomas may present this way on rare occasion.
Skull Trephination for Acute Epidural Hematoma. The middle meningeal artery lies between the temporal bone and the dura in a vulnerable area of the skull just in front of the ear and above the zygomatic arch on each side. Temporal bone fractures here can lacerate the artery, which then bleeds into the potential space between the inner surface of the skull and the dura. PEDS: This is an injury of young people, probably because the dura is less adherent to the skull in youth as compared to older persons. Typically, the patient receives a hard blow to the side of the head with a brief loss of consciousness. He or she regains consciousness but becomes lethargic about an hour or so later. (This is the “walk, talk, and deteriorate” presentation.) Weakness on the opposite side of the body occurs simultaneously. The appearance of a Babinski sign on the side of weakness is an early finding. A pupil dilates as the third cranial nerve (oculomotor) on the side of the hematoma becomes distorted by the uncus of the brain as it herniates downward through the tentorial notch. Seizures are common during the herniation process. Ultimately, the brainstem herniates, resulting in apnea and death.
Rescuing a patient from this inexorable and ultimately fatal process involves:
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Rapid sequence intubation (RSI) and moderate hyperventilation when the patient loses consciousness. Do not give long lasting paralytic or sedative. Etomidate as a sedative and succinylcholine as a paralytic are good choices.
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Administration of mannitol, 1 g/kg IV. Some neurosurgeons prefer hypertonic saline. (Consult with your neurosurgeon.)
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Administration of a loading dose of fosphenytoin 18 mg PE/kg IV at a rate of 125 mg/min or phenytoin 18 mg/kg IV at a rate of 50 mg/min.
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Insert a Foley catheter to prevent bladder distension.
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If the patient has a seizure, stop it with diazepam 5 to 10 mg IV.
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Observation for signs of further progression of the herniation process, such as pupil dilatation, seizure activity, and posturing.
If the herniation syndrome continues despite these first measures, perform skull trephination on the side of the hematoma. If a CT scan is unavailable, select the side of the skull on the side of the dilated pupil. The epidural hematoma is located on the side of the dilating pupil 80% of the time. An epidural hematoma can cause the opposite pupil to dilate by pushing the oculomotor nerve on that side against the tentorium. Rarely, the epidural hematoma will not be encountered by bilateral trephines as described.
Be decisive. Careful, rapid, and accurate assessment as the herniation syndrome unfolds allows you to act at the right moment. Neurosurgical standards state that this clot should be evacuated within 15 minutes of a determination that herniation is progressing. Consult with a neurosurgeon. The lucid interval between injury and deterioration means that the underlying brain is probably normal.
Procedure
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Elevate the level of the resuscitation cart so that the patient’s head is easily controlled and within easy reach. Adjust lighting. Shave and prep the sideburn area of the scalp. Drape off the area with sterile towels. An assistant should firmly grasp the patient's head to stabilize it during the procedure. Make a vertical scalp incision over the squamous portion of the temporal bone starting just above the zygomatic arch about 2 finger breadths in from of the tragus of the ear and going directly upward. Make the incision about 2 inches long.
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Continue the incision down through the underlying temporalis muscle, avoiding the temporal artery if possible. If brisk bleeding results, use Raney clips to control it. Insert a self-retaining scalp retractor to provide exposure and hemostasis. Expose an area of the skull about the size of a quarter (about 1 inch in diameter). Use a periosteal elevator to scrape the periosteum off of the skull, taking care to not let it slip under the zygomatic arch.
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Use a ½ inch Galt trephine with a detachable handle. Adjust the centering point of the Galt trephine (available from Sontec Instruments) so that it protrudes about 1/8 inch. Twist the spike and the trephine into the skull. When the trephine is cutting into the skull all around its circumference, retract the spike completely and continue twisting until the trephine has penetrated 4 mm or until you feel a slight give. Remove the trephine and attempt to remove the plug of skull with small Adson pickups with teeth. Continue twisting until it is loose. Clot and blood exude from the trephine. The patient improves immediately.
This trephine is more like a saw than a drill. You need not press hard to cut through the skull. The cutting portion is slightly conical; it will not plunge into the brain. Keep the skull plug sterile; send with the patient to tertiary center for neurosurgical definitive care. Use a Dandy nerve hook to gently tease clot from the trephine. Do not touch the brain or apply suction. Cover the wound with sterile dressing. Apply Raney clips to the scalp edges to control bleeding. Vol II—Disab Skills 2 Raney Scalp Clips
Give IV antibiotics, such as ceftriaxone 2 g IV (PEDS: 50 mg/kg up to 2 g in children). Keep the patient's chest and head elevated about 15 to 30 degrees if possible. Maintain cervical spine immobilization. Continue observation for signs of improvement or deterioration. Paralysis does not affect pupillary size or reactivity. Repeat neural exam frequently.
A
trephine tray should include a Wietlander self-retaining retractor, a
periosteal elevator,
a Dandy nerve hook, a Galt trephine, and a Raney
clip applicator forceps.
Reference
Rockswold GL, Pheley PJ. Patients who talk and deteriorate. Ann Emerg Med. 1993;22:1004-1007.