Computer-assisted three-dimensional reconstruction of head and neck tumors.

OBJECTIVE: Because head and neck tumors reside in a complex area, having a three-dimensional (3-D) model of the patient's unique anatomical features may assist in the delineation of pathology. The authors describe a new computer technique of 3-D anatomical reconstruction from two-dimensional computed tomography (CT) and magnetic resonance (MR) data and discuss how it represents a step forward in the continuing evolution of 3-D imaging. STUDY DESIGN: The authors selected three patients with solitary head and neck tumors and reconstructed their anatomy in a 3-D format for study. The tumors represented locations in the nose and central skull base (patient 1), temporal bone (patient 2), and neck (patient 3). MATERIALS AND METHODS: MR and CT images from the individual patients were electronically transferred to workstations in the Surgical Planning Laboratory of the authors' institution. Registration (or fusion) was carried out between the MR and CT images. The desired anatomic components underwent segmentation (identification and isolation). Assembly of the segmented images was performed and the resulting structures were integrated to produce a 3-D model. RESULTS: 3-D models of the following were constructed and displayed in an interactive format on high-capacity computer workstations: 1) a skull base sarcoma with extension into the nasopharynx and nose; 2) an acoustic neuroma with internal auditory canal involvement; and 3) a metastatic recurrence of a tongue base squamous cell carcinoma in the posterior triangle of the right side of the neck with extension to the skull base. CONCLUSION: The authors' Surgical Planning Laboratory has developed a 3-D reconstruction technique that has several new features. The models provided a very good 3-D interactive representation of the tumors and patient anatomy. The need now exists to develop this method of 3-D reconstruction of head and neck tumors for potential applications in treatment, research, and medical education.

A comparison of the results of KTP and CO2 laser stapedotomy.

Over the last 10 years, lasers have evolved to become an integral part of stapes surgery. Argon, KTP, and CO2 lasers have all been tested for their improved accuracy and safety in the middle ear. Because of the difference in optical properties between visible light (argon, KTP) and infrared (CO2) lasers, discussions have evolved around which laser is better and safer. In an effort to clarify the issues, a prospective comparison was made of 100 consecutive primary stapedotomies by using either the CO2 or KTP laser.

Osteomyelitis of the temporal bone and skull base in diabetes resulting from otitis media.

The report of a diabetic patient with pseudomonal osteomyelitis of the temporal bone and skull base not associated with an external otitis is presented. The infection started as a serous otitis media. The pathogenesis, clinical and radiologic features, and treatment of this rare condition are described and the literature is reviewed.

Infralabyrinthine approach to the internal auditory canal.

Multiple surgical procedures have been developed to expose the contents of the internal auditory canal. These include the middle fossa approach, the posterior fossa approach, the retrolabyrinthine approach, and the retrosigmoid approach. Each has its own unique benefits, as well as disadvantages. A new posterior-inferior approach to the internal auditory canal (the infralabyrinthine approach) has been developed. This approach affords exposure of at least the medial half of the internal auditory canal while remaining extradural and extralabyrinthine. By dissecting below the posterior semicircular canal, and remaining extradural, hearing is preserved. The dissection can proceed far enough laterally in the internal auditory canal to separate the cochlear and vestibular nerve divisions. Further anatomic considerations, as well as clinical applicability, will be discussed.

Hyperlipidemia in association with childhood sensorineural hearing loss.

In adults there has been an association noted between hyperlipidemia and sensorineural hearing loss. Etiologic considerations include hyperviscosity of the serum, vascular occlusion and an increased susceptibility to noise. Until now this correlation, to our knowledge, has not been made in the pediatric population. Several children with bilateral fluctuating sensorineural hearing losses have been identified with hyperlipidemia. The fluctuations in hearing varied with lipid levels. With dietary controls, the cholesterol levels returned to what would be near the norm for the pediatric population and hearing returned to near baseline. Unexplained fluctuating sensorineural hearing losses in children warrant the consideration of hyperlipidemia. Discovering a potentially reversible etiology for hearing loss is significant but more importantly, may lead to the early detection of hyperlipidemia in the young patient.

The effects of anesthesia on middle-ear effusions.

Surgeons occasionally note a discrepancy between preoperative assessment of middle-ear effusion and operative observation during the placement of ventilating tubes in children's ears. This study was designed to determine whether this variance is secondary to the effects of inhalation anesthesia or misinterpretation of the preoperative exam. Observations were recorded by three distinctly different methods of measurement: the surgeon, the MD-2 Impedance Analyzer, and the Acoustic Otoscope immediately before and after induction of anesthesia. These results were then analyzed and compared with the operative findings. Anesthetic induction was shown to cause alteration in the presence of middle-ear fluid in less than 10% of cases.

Head and neck applications of the milliwatt laser.

The head and neck surgeon often uses the carbon dioxide laser. With the advent of new instrumentation, the frequency of usage will increase. The CO2 miliwatt laser offers the advantages of tissue welding, as well as cutting and ablation by virtue of the small spot size produced combined with low power output. Potential applications include microvascular and microneural anastomoses. The milliwatt laser can be used endoscopically for tissue resection with a high degree of precision with power densities comparable to current CO2 lasers. Moreover, the milliwatt laser can be applied to otology for cutting and welding of the tympanic membrane, tissue removal, and stapedotomy.

Stapedectomy results in a residency training program.

As the total number of stapedectomy procedures has declined, the adequacy of residency training for this procedure must be evaluated. Results of 5 years of stapedectomies performed by the resident otology service at the Massachusetts Eye and Ear Infirmary from Oct 1, 1979, through Sept 30, 1984, are reviewed and compared with other published results. A suggestion is made for improving the residency teaching program.

Sudden hearing loss associated with piroxicam.

Tinnitus has been reported with use of piroxicam (Feldene) a nonsteroidal anti-inflammatory drug. Two cases of temporary hearing loss have also been reported. To the best of our knowledge the patient reported herein represents the first case of permanent hearing loss and tinnitus associated with use of the drug.

Bilateral congenital middle ear cholesteatomas.

Congenital middle ear cholesteatomas remain of interest because of their relative rarity and unknown origin. A 4-month-old child presenting with bilateral congenital middle ear cholesteatomas forms the basis for this report. The nature of the epithelial debris found suggests an external origin. An extended transcanal tympanotomy approach for removal, based upon an operative experience of 11 similar ears, will be discussed.

Intralabyrinthine schwannoma.

The diagnosis of intralabyrinthine schwannoma has been made either accidentally at the time of surgery or at postmortem examination. Brain stem evoked response audiometry and computerized tomography do not add to our ability to make this diagnosis clinically. A case is presented of an intralabyrinthine schwannoma found at the time of transmastoid labyrinthectomy. The literature is reviewed and a composite clinical picture is presented.

The relationship of stria vascularis volume and cochlear duct volume.

To determine whether stria vascularis volume correlated with cochlear duct volume, 1,180 human temporal bones were examined. Fifty-eight ears in 44 persons showed the presence of endolymphatic hydrops. Strial atrophy was found in 143 ears in 83 persons, in five of which it was severe. Eight cases of endolymphatic hydrops occurred in the presence of mild to moderate strial atrophy. A decrease in cochlear duct volume usually accompanied severe strial atrophy. However, a case in which cochlear duct volume was normal in the presence of severe strial atrophy was seen. Cochlear duct volume does not always correlate with stria vascularis volume.