Reto J. Bale

Minimally Invasive Head Holder to Improve the Performance of Frameless Stereotactic Surgery

Frameless stereotactic procedures crucially depend on the firmness of immobilization. Once registered, shifting of the patient leads to inaccuracy, and the patient registration has to be realigned. To overcome the drawbacks of conventional invasive fixation for neurosurgery and the widely accepted fixation with surgical tape in ENT, the Vogele‐Bale‐Hohner (VBH) head holder has been developed. It permits rigid, noninvasive fixation of the head by using an individualized dental cast attached to the upper jaw by vacuum. Oral intubation is uncomplicated. In addition, a special registration device providing well defined reference points can be mounted to the mouthpiece. We report the first promising clinical applications of this device.

Repositioning Accuracy: Comparison of a Noninvasive Head Holder with Thermoplastic Mask for Fractionated Radiotherapy and a Case Report

PURPOSE To compare accuracy, clinical feasibility, and subjective patient impression between a noninvasive head holder (Vogele Bale Hohner [VBH]; Wellhoefer Dosimetry, Schwarzenbruck, Germany) developed at the University of Innsbruck and the thermoplastic mask fixation system for use in fractionated external radiotherapy. We present a case report of an actual patient fixated in the VBH head holder during radiation therapy. MATERIALS AND METHODS The VBH head holder consists of an individualized vacuum dental cast connected to a head plate via two hydraulic arms allowing noninvasive, reproducible head fixation of even uncooperative patients. Accuracy was tested and compared with that of the thermoplastic mask using the Phillips EasyGuide navigation system on five volunteers. Specific external registration points served as landmarks and their positions were compared after each repositioning. System and operator inaccuracy were also taken into account. The times taken for production and repositioning of the respective fixation devices were compared, and subjective impressions were noted. RESULTS Mean VBH head holder repositioning accuracy was 1.02 mm while that of the thermoplastic mask was 3.05 mm. 69% of mask repositionings showed a deviation > 2 mm and 41% > 3 mm (as opposed to 8% and 1% respectively for the VBH head holder) Those points located farthest away from the respective plane of fixation showed the largest deviations. Both production and repositioning times were similar between the systems; depending upon the patient, the VBH head holder was generally better tolerated than the mask system. CONCLUSION Due to its significantly better repositioning accuracy compared to that of the thermoplastic mask, the VBH head holder is especially suited for external radiation requiring precise repositioning due to critical tissues in immediate surrounding of the area to be irradiated.

CT-MIBI image fusion: a new preoperative localization technique for primary, recurrent, and persistent hyperparathyroidism.

BACKGROUND Successful minimally invasive or imaging-guided operations in patients with primary, recurrent, and persistent hyperparathyroidism are based on the reliability of preoperative parathyroid localization studies. The CT-MIBI image fusion promises a higher diagnostic accuracy than current imaging procedures. The aim of our study was to assess its reliability in correctly detecting enlarged parathyroid glands. METHODS In a prospective study 24 consecutive patients underwent CT-MIBI image fusion as preoperative parathyroid localization procedure. The results of technetium 99m sestamibi single photon emission computed tomography (MIBI-SPECT) alone, today the standard method in parathyroid imaging, and CT-MIBI image fusion were analyzed by a blinded reviewer, and the imaging results were compared with the intraoperative findings. RESULTS For CT-MIBI image fusion a sensitivity of 93% and a specificity of 100% in correctly detecting the position of enlarged parathyroid glands was calculated and compared with a sensitivity of MIBI-SPECT of 31% and a specificity of 87% (P<.001). This new imaging technique enabled us to successfully treat 22 of our patients (92%) with imaging-guided surgery. Twenty (83%) underwent unilateral or minimally invasive operations. CONCLUSIONS CT-MIBI image fusion appears to be superior to MIBI-SPECT in preoperative parathyroid imaging. CT-MIBI image fusion can be performed on existing CT- and MIBI-SPECT units. We recommend this method for preoperative localization in patients with primary, recurrent and persistent hyperparathyroidism.

Computer‐Aided Surgery in the Petrous Bone

Objectives: We demonstrate that computer‐assisted frameless stereotactic navigation with the ISG/ELEKTA Viewing Wand system in the petrous bone is routinely possible with sufficient application accuracy.

Three-Dimensional Image-Guided Endonasal Surgery With a Microdebrider

We report the first intraoperative use of a microdebrider as a stereotactic three‐dimensional (3D) navigation instrument in paranasal and frontobasal surgery. The microdebrider uses rotating blades and an integrated suction device for controlled removal of tissue under video‐endoscopic view. The ISG Viewing Wand uses the patients computed tomography/magnetic resonance (CT/MR) data and a 3D reconstruction thereof and a highprecision position‐sensitive mechanical arm for intraoperative three‐dimensional navigation. We have linked the microdebrider to the Viewing Wand to transform it into a continuously available intraoperative stereotactic localizing device. We discuss the problems related to this extension of the Viewing Wand and demonstrate the practical use in an exemplary polypectomy.

VBH Head Holder to Improve Frameless Stereotactic Brachytherapy of Cranial Tumors

Precise target localization is essential for brachytherapy. We have adapted the VBH (Vogele-Bale-Hohner) head holder (Wellhoefer Dosimetry, Schwarzenbruck, Germany), originally developed at the University of Innsbruck, for frameless stereotactic surgery, for use in brachytherapy of cranial tumors. The VBH head holder allows for rigid, noninvasive head fixation by means of an individualized upper dental cast. Registration rods, rigidly attached to the dental cast, provide stable external points of reference. The dental cast is sucked against the upper palate by vacuum, and then the fixated patient is scanned. During simulation, the targeting device can be positioned with respect to the virtual patient using the ISG Viewing Wand. Following simulation, the real patient is repositioned under vacuum control, the targeting device repositioned as well, and the actual brachytherapy initiated. The VBH head holder is well tolerated by patients and simple to use, and various studies have confirmed submillimeter accuracy. The modified head holder in combination with a new targeting device allows for precise and well-planned insertion of hollow needles into a tumor using frameless stereotactic systems as well as being compatible for uses in other fields.

Einsatz der ISG Viewing Wand in der HNO-Chirurgie

Wir berichten Uber unsere Erfahrungen mit der ISG Viewing Wand, einem intraoperativen System zur computerunterstUtzten dreidimensionalen Navigation. Wir haben dieses System in unterschiedlichen chirurgischen Eingriffen an den NasennebenhOhlen, der vorderen SchAdelbasis und dem Felsenbein eingesetzt. Bis jetzt wurden mit diesem System 59 endonasale endoskopische Eingriffe durchgefUhrt, darunter 43 NebenhOhlenausrAumungen bei chronisch polypOser Sinusitis, 6 Orbitadekompressionen, 7 Tumorresektionen und -biopsien, und 2 Entfernungen von Aspergillomen. Versuchsweise verwendeten wir das System zur UnterstUtzung des Operateurs bei der AusrAumung eines Cholesteatoms. In keinem der FAlle stellte der Einsatz dieses Systemes eine Behinderung dar oder verursachte intraoperative Komplikationen. Unser radiologisches und klinisches Protokoll zur Datenerfassung und zur Eichung des Systems hat sich in der klinischen Routine ausgezeichnet bewAhrt. Der Einsatz von computerunterstUtzten Navigationssystemen stellt eine ausserordentliche Hilfe in der Lokalisation und Identifikation von anatomischen Strukturen dar. Zur Erweiterung des Einsatzspektrums der Viewing Wand, einem passiven «Navigator», entwickeln wir neue Techniken fur endoskopische endonasale Eingriffe im HNO-Bereich.

Perforated right colonic diverticulitis complicating pregnancy at 37 weeks' gestation.

Dear Editor: Diverticular disease of the colon represents a quite common clinical condition in developed countries, showing a tremendous preponderance in the left-sided colon. Its prevalence increases with age, reaching about 75% for those over the age of 80 years. In young adults diverticulosis is a rare condition. Thus, diverticular disease rarely affects gestation and is usually not taken into consideration when facing pregnant women with abdominal complaints. This letter has been written with the intent of sensitising this entity because complicated diverticulitis results in acute danger for both the mother’s and the unborn child’s lives. A 33-year-old pregnant woman was admitted for surgical consultation because of increasing right lower quadrant pain at 37 weeks’ gestation. Relevant previous medical history included the amputation of the right lower extremity for Ewing sarcoma during childhood. Throughout the 2 days preceding her admission, she had noticed the gradual onset of right lower and right mid abdominal pain accompanied with nausea and two episodes of vomiting. Neither chills, diarrhea, rectal bleeding nor other gastrointestinal symptoms were observed by the patient. Mild constipation since the onset of pregnancy was her only abdominal complaint over the last few months. On examination, the patient was afebrile and in good condition, the fundal height was correct for the gestational age. Her abdomen was soft and non-distended, but the right mid and lower abdomen were pressure-sensitive. There was no abdominal tenderness reflecting peritoneal irritation. Peristalsis sounds were normal and rectal examination was unrevealing. Laboratory examination showed an elevated white blood cell count and C-reactive protein of 15.3 g/l and 10.6 mg/dl respectively. Urine tested positive for leucocytes and erythrocytes, but was negative for nitrite. Abdominal ultrasound showed inflammatory infiltration of the paracaecal tissue and a faecalith of unclear location at the site of the appendix or the caecum. A singleton, vertexpresented fetus with growth parameters correct for gestational age and amniotic fluid volume was found. Following this first examination, the patient’s symptomatology was considered consistent with the start of appendicitis. Given the patient’s afebrile status, the discrete clinical findings and the patient’s negative clinical history concerning diverticulosis, diverticulitis was not considered to be causing the symptoms. In order to avoid surgery and allow for eventual spontaneous recovery and labour, in-patient conservative management with short-term clinical observation was prescribed. The patient received intravenous hydration, parenteral double antibiotics and anJ. Bodner (*) . G. Wetscher . W. Mark Department of General and Transplant Surgery, Innsbruck University Hospital, Anichstrasse 35, 6020 Innsbruck, Austria e-mail: johannes.bodner@uibk.ac.at Tel.: +43-512-50480763 Fax: +43-512-50422577

Computer-Assisted Interstitial Brachytherapy

We present the current state-of-the art of computer-assisted interstitial (fractionated) brachytherapy as a “picture-book” without wanting to give an in-depth presentation of either brachytherapy itself or of otolaryngologic aspects of oncologic treatment. However, our results show that 3D-computer-assisled navigation techniques can successfully be applied in interstitial brachytherapy to exactly plan the hollow-needle’s position(s) in order to reach a prospective planning of brachytherapy which exploits the full 3D-information of the modern imagery and incorporates state-of-the-art navigational techniques.

Computer-Aided Surgery in Otolaryngology

Endoscopic surgery of the paranasal sinuses is increasingly employed for the treatment of nose and sinus pathologies. However, despite the wide availability of excellent optical systems and high-resolution computed tomography, serious complications related to this surgical technique have been reported. May et al. (1994) reported an incidence of 0.85% for major complications and 6.9% for less serious ones. The major negative consequences include orbital damage (disturbances of vision and eyeball motility or position) and intracranial complications (haemorrhage, meningitis, anosmia, carotid or optical nerve lesions), while the reported minor complications are epistaxis and ecchymosis and/or periorbital emphysema. To reduce these risks, the techniques of image- guided neurosurgery are also being applied in the field of otorhinolaryngology. This type of surgery is particularly useful in cases where the anatomical landmarks are altered or absent (as in neoplasms and revision operations), in the presence of bleeding or rare anatomical variations such as sphenoethmoidal cells (Onodi cells) or infraorbital ethmoid cells (Haller cells), as well as in orbital decompression, optic nerve surgery, the draining of abscesses (orbital and epidural) and resection of tumours of the skull base (Anon et al. 1997; Fried et al. 1997; Anon 1998). Particular assistance in these conditions is given by frameless stereotactic systems, which enable visualization of the actual spatial location of the surgical instrument on preoperatively acquired images.