Clinical anatomy of the nasal process of the frontal bone (spina nasalis interna).

OBJECTIVES: During endonasal frontal sinusotomy with the sharp spoon, a solid piece of bone is frequently encountered anterior to the neo-ostium. This bone may be referred to as the nasal process of the frontal bone or internal nasal spine (spina nasalis interna). A prominent spina may render an extended sinusotomy difficult and may call for use of the drill. A series of anatomic measurements is presented to illustrate the 3-dimensional anatomy of the spina nasalis and the regional anatomy. METHODS: A maximum endonasal frontal sinusotomy (Draf type I-II procedure, nasofrontal approach type II) was performed on 36 anatomic specimens by means of a sharp spoon. The dimensions of the remaining nasal spine were measured subsequently together with the anterior-posterior diameter of the inferior frontal sinus, the thickness of the anterior frontal sinus wall, and the distance from the neo-ostium to the anterior ethmoidal artery. RESULTS: The individual microanatomy of the medial floor of the frontal sinus showed a wide range of variation. The average height of the individual spine was 10 mm, the maximum depth 6 mm. A correlation was found between the nasofrontal angle of the specimen and the anterior-posterior dimension of the spine: the more acute the angle, the thicker the spine. In three quarters of the cases, the neo-ostium was separated by just one anterior ethmoidal cell from the anterior ethmoidal artery. CONCLUSIONS: The presented investigations provide the surgeon with quantitative data on the individual anatomy of the nasal spine and offer additional information for selecting the appropriate surgical procedure in the individual patient.

Wound healing of mucosal autografts for frontal cerebrospinal fluid leaks--clinical and experimental investigations.

Wigand introduced in 1981 the concept of applying autogenous free mucosal grafts for small to middle-sized cerebrospinal fluid (CSF) leaks of the frontal skull base. This operative technique has proved to be successful in clinical use. However, the details of wound healing of the free graft and the host area of the skull base are largely unknown. We conducted a series of animal experiments using 21 rabbits. Standardized CSF leaks of the frontal skull base were created and then closed using free autogenous grafts from the nasal septum. Twenty specimens could be evaluated after different postoperative time intervals by means of conventional microscopy of histological serial sections. In addition, we carried out a small series of special clinical postoperative observations following routine sinus surgery for polypoid mucositis on our patients, applying free mucosal autografts to the intact frontal skull base. The autogenous free mucosal transplants underwent a rapid process of histological remodelling. All grafts showed a reduction in size of about 1/5. The respiratory epithelia mostly disappeared postoperatively. The main histological feature consisted of a fibrous transformation of the graft, starting 8 days postoperatively. The presented experiments and observations lay the foundation for optimizing the operative technique and the postoperative care of our patients suffering from CSF leaks.

Endonasal endoscopic closure of cerebrospinal fluid fistulas at the anterior cranial base.

This study reports our indications and limits for endonasal endoscopic closure of dural defects with a cerebrospinal fluid (CSF) leak at the anterior cranial base, and demonstrates our surgical technique. Fifty-three patients with CSF rhinorrhea were reassessed for the success rate of closure of the CSF leak. Surgery was successful in 98%, and 68% of fistulas were closed endoscopically. A free graft of autogenous mucoperiosteum of the inferior turbinate was the most frequently used tissue for defect closure. The endonasal endoscopic route proved relatively safe for the closure of dural tears, irrespective of the cause, up to about 10 x 10 mm. It is characterized by minimal morbidity because of the preservation of sinus ventilation and bony structures, supraorbital nerves, and olfactory fibers. Defects larger in size, predominantly of traumatic origin, were closed via the transfacial approach. The decision on the surgical approach was additionally based on the extent of the facial soft tissue injuries and the localization of the leak.