Neurosurg Rev DOI 10.1007/s10143-015-0647-x
Olfactory preservation during anterior interhemispheric approach for anterior skull base lesions: technical note Fumihiro Matano 1 & Yasuo Murai 1 & Takayuki Mizunari 2 & Kojiro Tateyama 1 & Shiro Kobayashi 2 & Koji Adachi 1 & Hiroyasu Kamiyama 3 & Akio Morita 1 & Akira Teramoto 1
Received: 12 May 2014 / Revised: 12 April 2015 / Accepted: 25 April 2015 # Springer-Verlag Berlin Heidelberg 2015
Abstract Anosmia is not a rare complication of surgeries that employ the anterior interhemispheric approach. Here, we present a fibrin-gelatin fixation method that provides reinforcement and moisture to help preserve the olfactory nerve when using the anterior interhemispheric approach and describe the results and outcomes of this technique. We analyze the outcomes with this technique in 45 patients who undergo surgery for aneurysms, brain tumors, or other pathologies via the anterior interhemispheric approach. Anosmia occurred in 4 patients (8.8 %); it was transient in 2 (4.4 %) and permanent in the remaining 2 (4.4 %). Brain tumors clearly attached to the olfactory nerve were resected in the patients with permanent anosmia. We found a significant difference in the presence of anosmia between patients with or without lesions that were attaching the olfactory nerve (p=0.011). Our results suggested that fibringelatin fixation method can reduce the reported risk of anosmia. However, the possibility of olfactory nerve damage is relatively high when operating on brain tumors attaching olfactory nerve. Keywords Anosmia . Anterior interhemispheric approach . Skull base . Aneurysm . Meningiomas Electronic supplementary material The online version of this article (doi:10.1007/s10143-015-0647-x) contains supplementary material, which is available to authorized users.
Introduction The anterior interhemispheric (AIH) approach was first reported by Ito in 1982 . A great view around the anterior communicating artery complex and hypothalamic lesion with minimal retraction are the most advantageous aspects of this approach . However, anosmia is described as a frequent complication associated with this approach . Olfactory disturbances may greatly influence the quality of life of patients and their nutritional intake . In the AIH approach, after the dura is incised and the cerebrospinal fluid (CSF) is drained, the frontal lobe falls away from the anterior skull base because of gravity, and the olfactory tract may be stretched and damaged. Moreover, the use of a retractor can injure the olfactory nerve by shearing or stretching the olfactory filaments, either via direct pressure from the spatula on the nerve or by destruction of the vessels supplying the olfactory structures . In our institution, to avoid these complications, before the interhemispheric fissure was dissected, the olfactory bulbs were dissected from the frontal lobe and fixed to the frontal base using a thin slice of gelatin sponge (Gelform® Baxter, Hayward, CA, USA) with fibrin glue. We named this method the fibrin-gelatin fixation method. Here, we report a surgical technique via the AIH approach using the fibrin-gelatin fixation method that helps decrease the incidence of anosmia.
* Fumihiro Matano [email protected]
Department of Neurological Surgery, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8603, Japan
Department of Neurological Surgery, Chiba Hokusou Hospital, Chiba, Japan
Department of Neurological Surgery, Teishinkai Hospital, Sapporo, Japan
We used the basic bifrontal craniotomy technique to prevent infection and CSF leakage by employing specific closed methods reported previously, which are briefly described below. We have never experienced CSF leakage or meningitis
after using this interhemispheric approach in more than 50 cases . Patients were placed in the supine position with their heads parallel to the horizontal plane. Bilaterally symmetrical skin incisions were made behind the hairline. A flap was turned down and the periosteal flap was reflected as a separate flap. Three burr holes were made and bifrontal craniotomy was performed. When the frontal sinus was opened, the frontal sinus mucosa was sutured using purse-string suture with 7-0 prolene, closed using a thin slice of gelfoam with fibrin glue, and packed with thin bone of the frontal sinus. Thereafter, the periosteal flap, which covered the bone cap, was sutured to the dura mater on the frontal base. This caused the separation of the four coating layers, comprising the pericranium, bone cap, fibrin glue, and mucous membrane from the subdural space within the frontal sinus, thereby preventing CSF leakage . Subsequently, the dura was incised in a BW-shaped^ fashion and reflected anteriorly. The superior sagittal sinus was ligated and divided at its most anterior part.
The fibrin-gelatin fixation method Before the interhemispheric fissure was dissected, the olfactory bulbs were carefully dissected from the frontal lobe without stretching them (Figs. 1 and 2) and fixed to the frontal base surrounding olfactory bulbs using a thin slice of gelatin sponge with fibrin glue, in an attempt to avoid direct injury, Bpeel away^ from cribriform plate, and xerosis of the olfactory nerve (Figs. 3 and 4) (video).
Fig. 1 Olfactory nerves were dissected from the frontal lobe before the interhemispheric fissure was dissected
Fig. 2 Schematic diagram illustrating olfactory nerves were dissected from the frontal lobe before the interhemispheric fissure was dissected
Step 1) Two layers of sliced gelatin sponge soaked in the fibrinogen component of fibrin glue were attached to the sutured area. Step 2) Thrombin solution was sprayed to achieve equal adherence. Step 3) Intraoperatively, the olfactory nerve with gelform and fibrin glue was moistened on at least an hourly basis with artificial CSF to avoid olfactory nerve injury and xerosis. Sliced gelfoam sponge moistened with fibrin glue is thick and provides adherence comparable to a simple fibrin glue spray, offering both reinforcement and moisture for the olfactory nerve. In addition, this method ensures that the fibrin glue
Fig. 3 Fixing and moisturization of the olfactory nerves to the frontal base using a thin slice of gelfoam with fibrin glue was performed to avoid olfactory nerve injury
Case material and methods
Fig. 4 Schematic diagram illustration of the fixation and moisturization of the olfactory nerves to the frontal base using a thin slice of gelfoam with fibrin glue was performed to avoid olfactory nerve injury
is spread thinly and evenly. Fibrin glue can be used for a suitable position certainly . In addition, the bilateral olfactory nerves were performed (Fig. 5). The dissection of the pericallosal cisterns and suctioning of CSF allowed the easy confirmation of the subarachnoid space located between the olfactory nerve and the medial frontal base. At this stage, the olfactory nerve was again separated from the frontal base toward the anterior perforating substance. The nerve was fixed to the frontal base using a thin slice of gelfoam with fibrin glue, which was occasionally moistened with artificial CSF in an attempt to avoid olfactory nerve injury and xerosis. To prevent damage to the encased olfactory nerve, the most important step is the preservation of the arachnoid and microvascular layers over the nerve.
Forty-five patients were included in the study between July 2004 and January 2014. Twenty-five patients had aneurysms, 7 had meningiomas, 6 had craniopharyngiomas, and 3 had pituitary adenomas. One patient each had a germinoma, glioma, fibrous dysplasia, and an arteriovenous fistula. Among these individuals, 23 were male and 22 were female. The mean age at surgery was 55.3 years (range, 20–77 years). The presence of anosmia was diagnosed on the basis of subjective symptoms. When the patient had subjective symptoms, we consulted the department of otorhinolaryngology for performing the Alinamin test . No patients had anosmia before operation. Statistical analysis was performed using SPSS for Mac (V.21.0; SPSS, Armonk, New York, USA). Variables are expressed as mean±standard deviation, median (interquartile range, 25th–75th percentile), or number of patients (%), where appropriate. Multivariate logistic regression analysis was performed using variables that were significantly associated with anosmia on univariate analysis (p