31 Trauma Flap and Osteo-Dural Decompression Techniques • Acute subdural hematomas. • Decompressive hemi-craniectomy for trauma or stroke with unilateral hemisphere swelling and midline shift. • Position: Patient is positioned supine. • Head: The head is flexed 10–15°, rotated 45° to the contralateral side (if no contraindications). • In case of unstable cervical spine: hard collar has to be kept with ipsilateral shoulder roll; alternatively, the patient might be placed in the lateral position to keep neck in neutral position. • Axillary roll is placed under the contralateral axilla. • Ipsilateral shoulder is pulled down to maximize the opening between head and shoulder. • Reverse question-mark incision (Fig. 31.1) ◦ Starting point: Incision starts at the zygomatic arch, < 1 cm anterior to the tragus. ◦ Run: Incision line runs superiorly and then curves posteriorly at the level of top of the pinna till 4-8 cm behind the pinna, then it is taken superiorly. The incision resembles a “reverse question-mark” shape. ◦ Ending point: It ends 1-2 cm lateral to the midline, behind the hairline. ◦ In case of scalp lacerations, it is advisable to try to incorporate them into the incision. Seek for foreign bodies and excise contused skin edges in elliptical fashion. • Branch of the facial nerve to the frontalis muscle. • Branches of the superficial temporal artery. • Myofascial level ◦ Myofascial level is incised according to skin incision. • Muscles ◦ The periosteum and the temporal muscle are divided using monopolar electrocautery. ◦ Using periosteal elevator and monopolar electrocautery, the scalp flap is detached along with the temporal muscle and reflected (as a single unit) antero-inferiorly. • Branch of the facial nerve to the frontalis muscle • Burr holes ◦ I: The first burr hole is placed at the low temporal area (temporal squama), right above the zygomatic arch. ◦ II: The second burr hole is made at the keyhole. ◦ III: The third burr hole might be placed, as preferred, along the planned craniotomy route. • Craniotomy landmarks ◦ Anterior: Orbital rim. ◦ Lateral: Zygomatic arch. ◦ Medial: 1 cm from the midline, sagittal suture. ◦ Posterior: Lambdoid suture. • Parenchymal, pial vessels or dural sinuses injury when elevating depressed fractures. • Dural sinuses. • “Cruciate/stellate” or in a C-shaped fashion. • Brain cortex. • Parenchymal structures: Lateral aspect of frontal, temporal and parietal lobes. • Arachnoidal layer: Sylvian fissure. • Arteries: Middle cerebral artery. • Veins: Superficial Sylvian vein, superior and inferior anastomotic veins, cortical veins of the lateral surface. • Indications: Bilateral brain swelling. • Schematic representation in Fig. 31.8 • Full description in Chapter 14.
31.1 Indications
31.2 Unilateral Craniectomy
31.2.1 Patient Positioning
31.2.2 Skin Incision
Critical Structures
31.2.3 Soft Tissues Dissection (Fig. 31.2)
Critical Structures
31.2.4 Craniotomy/Craniectomy (Figs. 31.3, 31.4)
Critical Structures
31.2.5 Dural Opening (Figs. 31.5, 31.6)
Critical Structures
31.2.6 Intradural Exposure (Fig. 31.7)
31.3 Variants
31.3.1 Bilateral Frontal Craniectomy