Radical excision of a craniobasal tumor involving the middle cranial fossa. Technical note

Craniobasal tumors affecting the middle cranial fossa are rarely treated radically; the main problem to solve is the presence of important nervous and vascular structures in this region. The Authors report a case of complete removal of a malignant tumor involving the temporal bone and the middle cranial fossa. Surgery was performed by the cooperation of the neurosurgical and the ENT teams.     

The versatile frontal sinus approach to the floor of the anterior cranial fossa. Technical note

A technique to expose the anterior cranial base is described with entry through the anterior and posterior walls of the frontal sinus. Burr holes are avoided in the visible portion of the forehead. Expansion of the operative field may be accomplished, if necessary, by supplemental superior frontal or supraorbital rim osteotomy. The technique is rapid, safe, and provides excellent operative exposure and superior cosmetic results.     

Clip-grafts in microvascular decompression of the posterior fossa. Technical note

A method is described for the protection of the trigeminal root from recurrent vascular irritation or compression after posterior fossa microvascular decompression. A vascular clip-graft, using a Sundt clip of suitable size, is applied to the sensory root of the trigeminal nerve. The technique has proven safe and effective in a series of nine patients followed for up to 28 months.     

Technical note: "look-ahead" navigation method for K-wire fixation in rhinoplasty.

OBJECTIVE: The Kirschner wire (K-wire) technique for fixation of rib cartilage grafts to the maxilla is a powerful tool in rhinoplasty. It gives the nose unparalleled anterior projection. However, the technique is challenging because of poor maxillary visualization through the open rhinoplasty approach. Inaccurate K-wire placement can cause dental injury or violation of the nasal/palatal mucosa. This study evaluates the efficacy of a surgical navigation system to guide K-wire placement. STUDY DESIGN: K-wires were placed, through an open rhinoplasty approach, into the maxilla of 12 fresh cadaver heads by a single surgeon. Six control specimens had K-wires placed without navigation. Six treatment specimens had K-wires placed with the "look-ahead navigation method," in which a surgical navigation device was attached to the K-wire gun. All maxillae were then sectioned to determine the final location of the K-wires. RESULTS: Four out of five (80%) of the K-wires were successfully placed in the treatment group, although only 3 out of 6 (50%) of the K-wires were successfully placed in the control group. One treatment K-wire was dislodged during the sectioning process and had to be excluded. The average K-wire deviation in the axial plane was less for the treatment group (0.2 +/- 0.4 mm) than for the control group (1.8 +/- 1.5 mm; P < .05). CONCLUSION: When surgical navigation is used in K-wired cartilage strut graft placement to maxilla, it can improve the accuracy of K-wire placement. This may result in reduced complications due to errant K-wire placement.     

New approach for cochlear implantation: cochleostomy through the middle fossa.

The middle fossa approach was used in 11 patients with profound bilateral hearing loss for insertion of a cochlear implant. Fibroadhesive otitis media (n = 1), bilateral cavity radical mastoidectomy (n = 1), autoimmune inner ear disease (n = 2), previous cranial trauma (n = 1), genetic prelingual deafness (n = 5), and otosclerosis (n = 1) were the causes of deafness. A cochleostomy was performed on the most superficial part of the basal turn, and the electrode array was inserted up to the cochlear apex. Speech perception tests (1-9 months after cochlear implant activation) yielded better results in these patients compared with a homogeneous group of postlingually deaf patients operated on through the traditional transmastoid route. Insertion of the implant through the middle fossa cochleostomy furnishes the possibility of stimulating areas of the cochlea (ie, the middle and apical turns) where a greater survival rate of spiral ganglion cells is known to occur, with improvement of information regarding the formants relevant for speech perception.     

Orbital surgery: repair of the frontal fossa by "en bloc" removal and self-replacement of the orbital roof. Technical note

The orbital roof may be repaired with implants or duplication of the frontal bone flap. A simple and safe method is presented in which a flap of orbital roof is "en bloc" removed and replaced to reconstruct the normal bony anatomy of the frontal fossa.     

Computer-generated surgical simulation of morphological changes in microstructures: concepts of "virtual retractor." Technical note

The authors' goal was to develop a computer graphics model to simulate the displacement and morphological changes that are caused by the retraction of fine intracranial structures. The authors developed an application program to interpolate the contour of models of an artery and a retractor. The center of the displacement was determined by spatial coordinates, and the shape of the displacement of the arterial model was calculated using a cosine-based formula with representation of a brain retractor. This computer graphics model was applied to the simulation of the displacement and morphological changes that occur when retraction is performed in the optic nerve. An illustrative case is presented, in which the optic nerve was displaced by a retractor to simulate the surgery performed in a carotid cave aneurysm of the internal carotid artery. The authors have named this methodological tool a "virtual retractor." This new navigational system for open microneurosurgery would be useful in teaching surgical microanatomy and in presurgical operative planning.     

Posterior fossa stereotaxic biopsy using the Brown-Roberts-Wells stereotaxic system. Technical note

Stereotaxic biopsy has been shown to be a reliable means of diagnosing posterior fossa lesions. The authors describe a technique for infratentorial transcerebellar stereotaxic access to posterior fossa parenchymal lesions using the Brown-Roberts-Wells apparatus in its standard commercial configuration. The necessity for tissue diagnosis of these lesions is briefly discussed.     

Identification of internal acoustic canal in the middle cranial fossa approach: a safe technique.

BACKGROUND: The middle cranial fossa approach (MCFA) is a very valuable functional approach in the armamentarium of the neuro-otologic surgeon. Identification of the internal acoustic canal (IAC) in MCFA is one of the most tedious steps. Many techniques have been described to locate the IAC safely when using the MCFA. OBJECTIVE: We sought to describe a safe technique for identification of the IAC and to demonstrate its feasibility in temporal bone dissections, as well as to discuss our clinical experience with this technique. METHODS: The surgical anatomy of the 20 temporal bones were evaluated and measured, especially by defining the medial and lateral ends of the IAC and relations to the nearby located structures. Measurements were obtained at 3 levels: the width of the IAC at the level of the fundus, the width of the IAC at the level of the porus, and the safe distance around the IAC at the meatal level. The medial and lateral IAC end widths were compared with each other and with the safe area at the meatal level. RESULTS: The smallest, the largest, and the mean values were recorded. The mean width of the IAC at the level of the porus was found to be more than 3-fold that of the width of the IAC at the level of the Bill's bar, and the ratio between the width of the medial safe area around the IAC and the lateral end of the IAC was found to be more than 7-fold as wide. CONCLUSION: This technique offers direct quick exposure of the IAC, without handling the facial nerve and the inner ear structures. Forty-five cases of operations with the same technique showed excellent ease and safety of identifying the IAC medially in the MCFA.     

Modifications to the orbitozygomatic approach. Technical note

The orbitozygomatic craniotomy is one of the workhorse approaches of skull base surgery, providing wide, multidirectional access to the anterior and middle cranial fossae as well as the basilar apex. Complete removal of the orbitozygomatic bar increases the angles of exposure, decreases the working depth of the surgical field, and minimizes brain retraction. In many cases, however, only a portion of the exposure provided by the full orbitozygomatic approach is needed. Tailoring the extent of the bone resection to the specific lesion being treated can help lower approach-related morbidity while maintaining its advantages. The authors describe the technical details of the supraorbital and subtemporal modified orbitozygomatic approaches and discuss the surgical indications for their use. Modifications to the orbitozygomatic approach are an example of the ongoing adaptation of skull base procedures to general neurosurgical practice.     

Temporalis myofascial repair of traumatic defects of the anterior fossa. Technical note

Bilateral temporalis myofascial flaps in continuity with frontal periosteum can be used in repairing extensive dural and bone defects of the anterior cranial fossa floor. The technique of preserving and using this flap is described and offers an alternative to the use of frontal pericranial tissue for repair of anterior dural defects.     

Retrolabyrinthine vestibular nerve section: a viable alternative to the middle fossa approach

Vestibular nerve section, whether by the middle fossa or retrolabyrinthine approach, is effective in relieving intractable vertigo while preserving hearing. However, the potential morbidity and technical difficulty of the middle fossa approach have limited its usefulness. In an attempt to determine if the two approaches produce comparable results, we evaluated 52 patients who underwent retrolabyrinthine vestibular neurectomy between April 1981 and March 1983 at the Otologic Medical Group. We compared their audiometric data and questionnaire responses with published data on patients who had a middle fossa vestibular neurectomy. Although differences between the two procedures do exist, the retrolabyrinthine method, with its 93% success rate in improving or resolving vertigo and its zero incidence of total sensorineural hearing loss, offers the surgeon a strong alternative to the middle fossa approach.     

Technical note: a "new" arthroscopic sliding knot

Sliding knots are an essential element of arthroscopic shoulder surgery. The authors have been using a previously undescribed arthroscopic sliding knot with good clinical success. This knot has been used in arthroscopic rotator cuff repair, arthroscopic shoulder stabilization, and arthroscopic SLAP repair. The technique of this knot is illustrated.     

Surgical anatomy of the extended middle cranial fossa approach

The extended middle cranial fossa approach includes removal of the petrous bone from its subtemporal surface in order to expose widely the internal auditory canal and the posterior fossa dura around its porus while preserving all the important and closely related anatomical structures. We have dissected 25 temporal bones and five fresh cadavers in order to define the limits of this approach. Measurements were obtained between the different structures to find reliable angles and distances that could guide working in this area. A new method of identification of the internal auditory canal is discussed based on the measurements taken.The results of the present work showed wide variations in the different structures. The arcuate eminence was coincident with the superior semicircular canal in only 48% of bones. Dehiscence of the geniculate ganglion and of the internal carotid artery was noted in 16% and 20% of specimens, respectively. The angles measured between the different structures showed great variations. However, the angle between the internal auditory canal and superior petrosal sinus was constant. Though the extended middle cranial fossa is a versatile approach, it affords a limited access to the cerebellopontine angle. A thorough understanding of the complex and variable anatomy of this area is necessary should this approach be utilized.     

Frontal sinus approach to the orbit. Technical note

The authors have previously advocated a supraorbital approach to tumors of the orbit. In this paper, they describe a technique in which they take advantage of a large frontal sinus as a means of entering the orbit without the necessity of intracranial exposure, as required by the more conventional supraorbital approach. This is achieved without frontal burr holes, allowing for a superior cosmetic result. The anterior wall of the frontal sinus is removed, and with it the roof of the orbit as a single bone flap. A case in which this technique was used is described.     

Transantral transsphenoidal approach to the pituitary. Technical note

The authors describe the technique of a transantral transsphenoidal approach to the sella turcica. The advantages and potential complications are discussed. This procedure may also be applicable when dealing with tumors of the skull base and orbits.