Marcus D. Atlas

A New Technique for Hypoglossal‐Facial Nerve Repair

Hypoglossal reinnervation of the facial nerve may be required after a proximal facial nerve injury. The classic hypoglossal‐facial graft procedure involves transection of the donor hypoglossal nerve, resulting in hemiglottic paralysis that, in association with paralysis of other cranial nerves, may cause speech and swallowing difficulties. Multiple lower cranial nerve palsies in conjunction with facial paralysis, as may occur after procedures such as skull base surgery, contraindicate the use of such techniques. The successful use of XII‐VII “interposition jump grafts” without hemiglossal weakness has been described However, a prolonged recovery period and weaker facial reanimation have been seen. In order to attain maximum facial reinnervation while preserving hypoglossal function, we have developed a new technique of XII‐VII repair. This method involves mobilization of the intratemporal portion of the facial nerve remnant, achieving a single anastomosis with the hypoglossal nerve, which has been partially incised. This technique has been used in three patients to date, with 6 to 11 months follow‐up. In all cases facial tone and symmetry have been restored and voluntary facial expression accomplished. The authors conclude that by employing the techniques described highly satisfactory cosmetic and functional results may be expected, without compromising hypoglossal nerve function.

Imaging Destructive Lesions of the Petrous Apex

Cholesterol granuloma and cholesteatoma are the two most common destructive lesions of the petrous apex. Arachnoid cyst is less common. These three expansile lesions are often indistinguishable on clinical grounds. Cholesterol granulomas can be treated effectively through internal drainage into the mastoid cavity or middle ear. Cholesteatomas, however, are managed by more aggressive and complicated removal, which often mandates the sacrifice of hearing. Symptomatic arachnoid cysts are amenable to simple surgical drainage. Therefore, accurate preoperative recognition on computed tomography (CT) and magnetic resonance imaging (MRI) is important in planning proper treatment. Thirteen cases of destructive lesions of the petrous apex are analyzed. The authors experience illustrates that the “typical” CT and MRI radiographic features are diagnostic in some cases, but not in all. In this study the pathologic findings have been correlated with the radiologic features on both MRI and CT.

Evolution of the Management of Hydrocephalus Associated with Acoustic Neuroma

The management of hydrocephalus in association with a cerebellopontine angle tumor is controversial. There is a widely held belief that initial therapy should always be directed toward treatment of hydrocephalus before definitive surgery. The potential problems of cerebrospinal fluid (CSF) shunting and drainage have led to an evolution in the management of hydrocephalus at St. Vincents Hospital. There is growing evidence that complete removal of cerebellopontine angle tumors will result in resolution of hydrocephalus without requiring other methods of CSF decompression. The authors present their experience of 14 patients with hydrocephalus found in a recent series of 104 consecutive cases of acoustic neuroma. This study has detected a significant correlation between hydrocephalus and increasing tumor size (P=.0234). The mean tumor size in this series was 3.8 cm. The series has also demonstrated that successful, safe, and complete tumor removal can be achieved without CSF drainage before surgery.

Hearing preservation in acoustic neuroma surgery: A continuing study

Hearing preservation in acoustic neuroma surgery is possible in a limited number of cases. Although there have been many articles published about hearing preservation, there have been few studies of long‐term hearing results, nor is it known if there is an increased rate of tumor recurrence when hearing preservation is attempted. Twenty‐two patients who underwent a hearing preservation procedure via the retrosigmoid approach were selected from 80 consecutive patients with cerebellopontine angle tumors operated on from February 1984 to November 1987. Useful hearing was retained in 11 cases as reported in a previously published study. Seven patients continue to have useful hearing after 3 to 5 years; 3 have shown a gradual but slight decline. There has been no tumor recurrence in these patients, but 2 patients, operated on early in the series and who had lost hearing, had recurrent tumor.

Calcification of Internal Auditory Canal Tumors

The diagnosis of tumors of the internal auditory canal (lAC) has been greatly simplified by the development of evoked response audiometry, computed tomography (CT), and, more recently, magnetic resonance imaging. The presence of calcification in the lAC is commonly thought to indicate a meningioma. 1.2 However, calcification can occur in other tumors, including acoustic neuroma. We report three cases of calcified intracanalicular tumors believed to be meningioma, but this diagnosis proved to be accurate in only one case.

Multichannel auditory brainstem implantation: the Australian experience

The multichannel auditory brainstem implant (ABI) provides the potential for hearing restoration in patients with neurofibromatosis type 2 (NF2). Programmes for auditory brainstem implantation have been established in two Australian centres. Eight patients have been implanted under the protocol of an international multi-centre clinical trial. Three patients had ABI insertion at the time of first side tumour removal, four at second side tumour removal and one after previous bilateral surgery where there was some residual tumour. The translabyrinthine approach was used in all cases. Successful positioning of the electrode array was achieved in seven of eight patients, all of whom achieved auditory perception with electrical stimulation. Intra-operative electrically evoked auditory brainstem response testing was successful in four patients and was useful in confirming correct electrode position. In six cases post-operative psychophysical and auditory perception testing demonstrated that useful auditory sensations were achieved. Five of these patients regularly used the implant. In one patient electrode placement was unsuccessful and only non-auditory sensations occurred on stimulation. In the remaining patients non-auditory sensations were minimal and avoidable by selective electrode programming. Auditory brainstem implantation should be considered in patients with NF2. The greatest benefit is seen in patients without debilitating disease who have non-aidable hearing in the contralateral ear.

Diffuse neurofibroma obstructing the external auditory meatus

A case is presented of a 36-year-old male with narrowing of the external meatus due to a diffuse neurofibroma. This unusual variety of neurofibroma spreads superficially and has many ecstatic blood vessels. The size, vascularity, uncertain edges and a tendency to recur makes surgical removal difficult. The treatment options are discussed.

The Cerebellopontine Angle: Does the Translabyrinthine Approach Give Adequate Access?

A long‐standing but unfounded criticism of the translabyrinthine approach is the misperception that this approach does not give adequate access to the cerebellopontine angle. Because of what is perceived as limited visualization and operating space within the cerebellopontine angle, some surgeons still believe that the translabyrinthine approach is inappropriate for large acoustic tumors. In this study, the surgical access to the cerebellopontine angle by virtue of the translabyrinthine approach is measured and analyzed. The parameters are compared with those measured for the retrosigmoid approach. This series objectively confirms that the translabyrinthine approach offers the neurotologic surgeon a shorter operative depth to the tumor, via a similar‐sized craniotomy. This permits superior visualization by virtue of a wider angle of surgical access. Such access is achieved with the merit of minimal cerebellar retraction.

Evaluating the Role of Magnetic Resonance Imaging Scans in the Surgical Management of Acoustic Neuromas

Objective To assess the reliability of magnetic resonance imaging (MRI) in predicting the size and position of an acoustic neuroma, with particular reference to the intracanalicular portion.Objective To assess the reliability of magnetic resonance imaging (MRI) in predicting the size and position of an acoustic neuroma, with particular reference to the intracanalicular portion. n n n nStudy Design Prospective study comparing the position of the tumor in the internal auditory canal on fast spin-echo MRI with the actual position measured intraoperatively. n n n nMethods The study was performed in a tertiary referral neurotology center, encompassing both the public and private health care systems. Fifteen consecutive patients admitted for acoustic neuroma removal via the translabyrinthine approach were studied. The main outcome measure was tumor position in the internal auditory canal expressed in millimeters, accurate to the nearest 0.5 mm. n n n nResults The fast spin-echo MRI was accurate within an error of 1 mm in predicting the lateral extent of the tumor in the internal auditory canal. n n n nConclusion Fast spin-echo MRI can accurately predict the lateral extent of an acoustic neuroma and allow accurate planning of the surgical approach.

The management of dysphagia in jugular foramen surgery

From 1985-1994, the Skull Base Unit at St. Vincents Hospital, Sydney, operated on 61 patients with tumours involving the jugular foramen. Pre-operative assessment by a Speech Pathologist and the institution of swallowing techniques prior to surgery have improved post-operative morbidity. Ancillary procedures at the time of surgery were not required in the majority of cases. An individual assessment of each patient early in the postoperative period was found to be more important with regard to the benefits of supplementary surgery. The majority of patients with dysphagia settled with conservative management and only a few underwent ancillary surgery. It is perceived that the cortical and subcortical control of swallowing is a major factor in the rehabilitation of these patients.