Technique

The dressing is applied in similar manner to the initial postoperative dressing. First, a vertical gathering tie is placed in the temporal fossa. Dressing sponges (4 × 4) are folded in half and placed directly over the fat graft and in the postauricular sulcus to support the auricle (Fig. 60-1A). Next, fluffed Kerlix is placed over the 4 × 4 sponges and the auricle (Fig. 60-1B). A tight wrap of roller gauze is applied (Fig. 60-1C). The direction of the wrap should be from the ear toward the occiput, which ensures that the auricle is not damaged by anterior folding. Also, the vertical tie must be as lateral as possible in the temporal fossa to avoid a pressure point on the forehead. Pressure necrosis of forehead skin can develop easily if attention is not given to this point.

FIGURE 60-1 A, Folded 4 × 4 dressing sponges placed over fat graft site after translabyrinthine acoustic tumor removal. Sponges are also placed in the postauricular crease to support the auricle. B, Fluffed Kerlix in place over 4 × 4 sponges. C, Appearance of dressing after roller gauze wrap. Tape can be applied to secure the position of the dressing; this is especially helpful on the forehead, where the dressing may slide inferiorly onto the brow. Note laterally placed vertical gathering tie. D, Ace wrap in place. Tape can be helpful to stabilize the elastic dressing.

The last layer of this dressing is a 3-inch elastic bandage, which provides the final compression (Fig. 60-1D). The elastic bandage should be wrapped firmly, but patient comfort must be accommodated. Usually, the last several turns can be altered to adjust the exact amount of compression. Ideally, a pressure dressing should be left in place for 4 or 5 days, which allows time for healing of the CSF leak site to occur. A minimum of 48 hours without leakage must pass before the dressing is removed.

In addition to the pressure dressing, other conservative actions should be undertaken. These measures all are directed at decreasing CSF pressure. Straining (Valsalva maneuver) is strictly avoided, and the patient is kept at bed rest with the head elevated 45 degrees. Limited activity, such as bathroom privileges or brief periods of sitting up in a chair, is at the surgeon’s discretion. Stool softeners and cough suppressants can be used. Acetazolamide (Diamox) may be given to decrease CSF production.

Technique

To place the catheter, a lumbar puncture is performed at the L4-L5 level. The patient is placed in either a sitting or a lateral decubitus position. The spinous processes are palpated, and L4-L5 is identified at the level of the iliac crest. The patient is asked to flex the back and bring the knees and chin to the chest. A prepared catheter kit contains all the necessary supplies for preparing, draping, and anesthetizing the site. A 14 gauge Tuohy needle is introduced in the midline with a slightly superior angle between the spinous processes (Fig. 60-2). The obturator is removed at intervals so that the surgeon can look for a flow of CSF. When a good flow of CSF is established, the epidural catheter is introduced through the needle and threaded into the epidural space. The opened side of the bevel of the needle faces the patient’s left or right side on penetrating the spinous ligaments and arachnoid. Before the catheter is threaded, the bevel is turned to open superiorly, facilitating directing the catheter cephalad. With a flow of CSF established, the needle is withdrawn, and the connector is placed on the end of the catheter so that a connection to intravenous tubing can be made. An empty intravenous fluid bag is attached to the tubing, and all connections are secured with tape (Fig 60-3A).

FIGURE 60-2 A, Tuohy needles used for lumbar puncture. B, Close-up of end of Tuohy needle.

Several methods of regulating CSF output exist. This regulation is important because, if CSF is removed too rapidly, tension pneumocephalus and brain herniation can occur.^1–3 Alternatively, if an inadequate amount of CSF is removed, the purpose of the drain is defeated. Humans produce approximately 18 mL of CSF per hour. The natural mechanisms of CSF absorption reduce some CSF; the lumbar drain should remove less than 18 mL of CSF per hour. Common neurosurgical practice is to order 50 mL of CSF removed every 8 hours.

Gravity is the standard method of effecting CSF drainage. The collection bag is placed at the level of the patient’s heart or below to create increasing output of CSF as needed. This method requires extremely attentive nursing care to ensure the proper amount of drainage. Drains placed to respond to gravity have highly variable output, and a change in patient position may significantly increase or decrease flow. Establishing an even flow of CSF is difficult, and usually a bolus of fluid is removed, after which the drain is clamped. The system is at risk of occluding during these clamped periods. If flow becomes impaired, removing the amount of CSF ordered becomes impossible.

To avoid some of these problems, we place the intravenous tubing in reverse direction through an intravenous infusion pump. The pump is set at a rate of 6 to 10 mL/hr, and a slow, controlled, continuous flow of CSF is withdrawn from the patient (Fig. 60-3B). Because this system is not gravity dependent, patients may move about without fear of a rapid discharge of CSF. Better patency of the catheter system is maintained because the flow is never stopped. If any occlusion of the system or air in the line is sensed, an alarm is sounded as the pump stops. Other physicians have employed flow-regulated systems,^4,5 but the system described here is a definite improvement over those described. We have employed this system in a large series of patients and have found it vastly superior to gravity drainage.

FIGURE 60-3 A, Site of lumbar puncture at L4-L5 with epidural catheter secured in place by Tegaderm. This provides an occlusive seal over the catheter site and allows for easy inspection of the site. B, IMED pump set up to withdraw cerebrospinal fluid from the patient and into the collection bag.

While the lumbar drain is in place, the patient must be closely observed for signs of infection. The temperature, surgical wound, lumbar drain site, and white blood cell count must be monitored. Samples of CSF may be examined at any time. Headache during CSF drainage is common, but meningismus should not be present. Prophylactic antibiotics are controversial, but are administered by some surgeons. As with a pressure dressing, the lumbar drain should be left in place for 4 or 5 days. We often shut the pump off for the last 24 hours so that if the leak recurs, the drainage can be resumed.

Technique

Ear Canal Closure with Eustachian Tube and Middle Ear Obliteration

In cases with no residual hearing, blind sac closure is the technique of choice. Blind sac closure of the ear canal is accomplished through a postauricular incision with transection of the ear canal. The canal skin is separated from the cartilage of the lateral canal and everted through the external auditory meatus. This everted canal skin is oversewn with a nonabsorbable suture that is left in place for 10 days postoperatively (Fig. 60-4). A flap of mastoid periosteum is developed on a pedicle just posterior to the external auditory canal. This flap is rotated anteriorly and secured as a second layer of closure for the meatus (Fig. 60-5). Next, all canal skin, the tympanic membrane, the malleus, and the incus are removed. To ensure complete removal of squamous epithelium and to enlarge the canal, a canalplasty is performed with a cutting burr. The eustachian tube is curetted and packed with Surgicel, temporalis muscle, and bone wax. Before wound closure, the middle ear and remaining canal are packed with additional muscle. A pressure dressing is placed for 4 postoperative days; a lumbar spinal fluid drain can also be used in the initial postoperative period.

FIGURE 60-4 A, Postauricular approach and transection of ear canal skin and dissection of cartilage from canal skin. B, Everting stitches placed in superior and inferior canal skin. These sutures are grasped with a hemostat placed through the canal and then pulled through, everting the canal skin. C, Everted canal skin is oversewn.

FIGURE 60-5. A, Mastoid periosteal flap is developed for second layer of closure and is pedicled just posterior to meatus. B, Flap is rotated anteriorly and secured with absorbable sutures.

FIGURE 60-6. Middle fossa exposure with removal of tegmen tympani and bony eustachian tube (ET) roof. Cochlea, vestibular labyrinth, facial nerve, and internal auditory canal are also shown.

FIGURE 60-7. A and B, Obliteration of bony eustachian tube with bone wax, bone pâté, and muscle. Inset (B) is a cross section of eustachian tube (ET) showing relationship of internal carotid artery (ICA), tensor tympani muscle, and greater superficial petrosal nerve.

In cases of CSF leak after middle fossa craniotomy in which the tympanic membrane is not intact, one closure option is blind sac closure of the ear canal followed by placement of a bone-anchored cochlear stimulator (Baha implant, Cochlear). Baha placement in this instance would overcome the maximal conductive hearing loss induced by a blind sac closure.