Temporal Lobectomy

Abstract

The indications for removal of a lobe from the cerebral hemisphere are discussed in Chapter VII (frontal lobectomy). The position of the patient on the operating table is seen in Fig. 257a or 257 b. The scalp incision and craniotomy are outlined in Fig. 258. The craniotomy reaches about 3¹/₂ cm. posterior to the external acoustic meatus. After the bone flap which hinges on the temporalis muscle has been turned, the remaining squama of the temporal bone (shaded area in Fig. 258) is removed down to the floor of the middle fossa by a rongeur. In Fig. 259 the dura is opened and the broken line indicates the incision to be made into the cortex. Over the nondominant hemisphere the excision may be extended to include the posterior third of the superior temporal gyrus and the bordering superior marginal gyrus. On the dominant side the posterior third of the superior temporal gyrus should be avoided to prevent sensory aphasia (Wernicke). In a unilateral temporal lobe lobectomy, including the transverse temporal gyri, no hearing difficulties are observed. The communicating vein of Labbé cannot be used as an anatomical landmark because of its irregular and unpredictable anatomical position. The bridging veins over the anterior part of the temporal lobe are coagulated and cut near the brain and not near the sinuses. These veins are exposed by riding along the sphenoid ridge with a brain spatula (Fig. 260). It is important not to miss the most medial and inferior veins which drain into the cavernous sinus on the undersurface of the temporal lobe (Fig. 32, p. 28). The cortex of the superior temporal gyrus is incised after we coagulate the pia arachnoid and superficial layers of the cortex. Care is taken to spare the Sylvian vein. The white matter is divided bluntly with a brain spatula, the temporal horn is entered and is covered with a cotton strip to prevent any blood from entering the ventricular system. The choroid plexus is clipped, coagulated and cut. Bipolar coagulation is preferred. Several branches of the middle cerebral artery which go over the temporal tip are clipped and sectioned. It is important to avoid clipping any major branch of the middle cerebral artery which takes a forward loop before it enters the island of Reil. The superior surface of the temporal lobe is left behind (Fig. 261) to preserve the hidden transverse temporal gyrus of Heschl. If the objective in removal of the temporal lobe is primarily to give internal decompression, the excision is stopped at the collateral sulcus and rhinal fissure (Fig. 262). When we expose the undersurface of the temporal lobe and if a lateral (fusiform) branch of the posterior cerebral artery has to be divided, the main trunk of the posterior cerebral artery must be left intact to prevent a cerebral infarction to the occipital lobe.