✓ The authors describe a simple technique by which a postoperative subgaleal cerebrospinal fluid fistula is treated by local tapping and injection of fibrin sealant through the same needle.
Tomas Menovsky, Joost de Vries and Heinz-Georg Bloss
Tomas Menovsky and Jacobus J. van Overbeeke
With recent developments in neurosurgery and related disciplines, more aggressive approaches are being made for various lesions of the skull base, and, as a consequence, cranial nerves are more frequently damaged, which causes significant morbidity. The authors review experimental and clinical studies involving surgical repair of severed cranial nerves and provide evidence that some degree of functional regeneration occurs. Functional recovery after repair is mainly dependent on the preoperative function of the muscle-nerve unit and the morphological organization of the nerve; the more complex the organization, the lesser the degree of functional recovery. The beneficial effect of surgical repair on postoperative morbidity is outlined together with suggestions for future research.
Dirk De Ridder and Tomas Menovsky
✓Isolated abducent palsy is a symptom that can be caused by many different intracranial pathological conditions. In this report the authors describe the case of a patient who suffered isolated abducent palsy resulting from vascular compression of the sixth cranial nerve; surgical treatment consisted of microvascular decompression (MVD).
This 56-year-old man presented with short-lasting episodes of a pulling sensation at the lateral side of his right eye associated with intermittent diplopia, followed by a progressive palsy of the abducent nerve and constant diplopia. Magnetic resonance imaging revealed a neurovascular contact of a dolichoectatic basilar artery with the abducent nerve. The patient underwent surgery consisting of a combined supra- and infratentorial presigmoid approach and subsequent MVD of the abducent nerve. Postoperatively, the abducent nerve palsy resolved within days, and the patient remains free of symptoms with a follow-up time of 4 years.
This is the first report of a neurovascular compression of the abducent nerve treated successfully by MVD.
Tomas Menovsky and Johan F. Beek
Object. This study was undertaken to evaluate CO2 laser—assisted nerve repair and compare it with nerve repair performed with fibrin glue or absorbable sutures.
Methods. In eight rats, the sciatic nerve was sharply transected and approximated using two 10-0 absorbable sutures and then fused by means of CO2 milliwatt laser welding (power 100 mW, exposure time 1 second per pulse, spot size 320 µm), with the addition of a protein solder (bovine albumin) to reinforce the repair site. The control groups consisted of eight rats in which the nerves were approximated with two 10-0 absorbable sutures and subsequently glued using a fibrin sealant (Tissucol), and eight rats in which the nerves were repaired using conventional microsurgical sutures (four to six 10-0 sutures in the perineurium or epineurium). Evaluation was performed 16 weeks postsurgery and included the toe-spreading test and light microscopy and morphometric assessment. The motor function of the nerves in all groups showed gradual improvement with time. At 16 weeks, the motor function was approximately 60% of the normal function, and there were no significant differences among the groups. On histological studies, all nerves revealed various degrees of axonal regeneration, with myelinated fibers in the distal nerve segments. There were slight differences in favor of the group treated with laser repair, in terms of wound healing at the repair site. In all groups, the number of axons distal to the repair site was higher compared with those proximal, but the axon diameter was significantly less than that in control nerves (p < 0.05). There were no significant differences in the number, density, or diameter of the axons in the proximal or distal nerve segments among the three nerve repair groups (p < 0.05), although there was a trend toward more and thicker myelinated axons in the distal segments of the laser-repaired nerves.
Conclusions. It was found that CO2 laser—assisted nerve repair with soldering is at least equal to fibrin glue and suture repair in effectiveness in a rodent model of sciatic nerve repair.
Jacobus J. van Overbeeke, Johannes R. M. Cruysberg and Tomas Menovsky
✓ The authors report the case of a 37-year-old woman in whom the trochlear nerve was transected during removal of a meningioma in the cavernous sinus and subsequently repaired by using microsurgical techniques. This patient presented with a tumor in the posterior part of the right cavernous sinus with expansion over the tentorium. Preoperatively, she suffered from partial deficit of the right trochlear nerve. Intraoperatively, the trochlear nerve was noted to be completely encased by the tumor and was totally divided during removal of the lesion. After tumor resection, the trochlear nerve was repaired by using a sural nerve fascicle secured with sutures and fibrin glue. Six months after the operation, trochlear nerve regeneration became evident as the patient's binocular vision gradually improved. The patient regained normal functioning of the superior oblique muscle 3.5 years after surgery. It is concluded that repair of a divided trochlear nerve is worthwhile and can be followed by successful regeneration and an excellent functional recovery of the superior oblique muscle.
Joost de Vries, Hans Peter M. Freihofer, Tomas Menovsky and Johannes R. M. Cruysberg
✓ A case of surgical repair of progressive exophthalmos of the right eye in a 43-year-old woman with neurofibromatosis Type 1 (NF1) is presented. Preoperatively, the patient's ocular movements and visual fields were intact. Visual acuity was 20/30 on the right side and 20/20 on the left. Computerized tomography scanning demonstrated complete absence of the superolateral orbital wall on the right side with a large meningocele protruding into the right orbit. Intraoperatively, a new superolateral wall was constructed using the inner table of the left frontal bone as a bone transplant. A free galeoperiosteum flap was used for water-tight dural reconstruction. A few weeks postoperatively the patient's exophthalmos showed remarkable resolution. Her ocular movements, visual acuity, and visual fields remained unchanged. In conclusion, reconstruction of the superolateral wall and repair of a meningocele in a patient with NF1 is worthwhile and can be followed by excellent cosmetic results. More important, the patient's visual functions remain preserved.
Tomas Menovsky, Niels Kamerling, Mark Plazier and Andrew I. Maas
Joost de Vries, Tomas Menovsky and Koen Ingels
In this study, the olfactory nerve function (ONF) in patients with an aneurysmal subarachnoid hemorrhage (SAH) who underwent neurosurgical clip occlusion for intracranial aneurysm was assessed pre- and postoperatively.
In 13 patients with an aneurysmal SAH who underwent a frontobasal or frontotemporal neurosurgical procedure for clipping of a ruptured intracranial aneurysm, ONF was assessed pre- and postoperatively by using a standardized olfactory test battery (“Sniffin' Sticks”). Preoperative testing was performed within the first 72 hours after SAH. For their follow-up visit, patients were tested 3 months after surgery. Olfactory thresholds, odor discrimination, and odor identification were documented. Only cooperative patients were included, and as a result, all patients enrolled in the study were classified in Hunt and Hess Grade II.
After SAH and before surgery, three patients were normosmic, seven were hyposmic, and three were anosmic according to the Sniffin' Sticks test. Thus, 10 of 13 patients with SAH already showed disturbance of ONF preoperatively. Of these 10, however, only two patients experienced reduced smell and taste sensation. At the 3-month follow-up review, 10 patients could be tested. Three normosmic patients remained normosmic. In one patient, ONF had improved from anosmic to hyposmic, whereas in another patient, ONF had worsened from hyposmic to anosmic. Thus, in eight patients, ONF remained unchanged after surgery. Three patients reported disturbed smell and/or taste sensation. One anosmic patient had experienced no smell sensation since surgery; however, he reported his taste to be normal. Another hyposmic patient experienced both reduced smell and taste sensation. One normosmic patient reported normal smelling ability but disturbed taste sensation.
This study provides evidence that aneurysmal SAH causes disturbance of ONF in a substantial number of cases. With the exception of one case, neurosurgical treatment did not alter a preexisting olfactory deficit. Improvement of SAH-induced olfactory dysfunction at follow-up, however, can also be documented. The subjective assessments of the patients do not correspond well with the test battery results.
Tomas Menovsky, Joost de Vries, Johannes A. L. Wurzer and J. Andre Grotenhuis
✓ The authors determined the landmarks and coordinates for intraoperative ventricular puncture directly from the supraorbital craniotomy opening via an eyebrow incision.
Fifty magnetic resonance (MR) imaging studies were obtained from patients with no pathological cerebral characteristics or ventricular distortion. The cerebral entry point of the ventriculostomy was located directly under the key bur hole (just behind the zygomatic process of the frontal bone) at the base of the frontal lobe because it represents a stable, reliable point that can be used as the bur hole during supraorbital craniotomy via an eyebrow incision. From this point, the coordinates for lateral ventricular puncture were determined using MR imaging studies and neuronavigational software.
The cerebral entry point of the ventriculostomy was situated directly under the key bur hole at the base of the frontal lobe. The catheter was directed at a 45° angle to the midline and a 20° angle up from an imaginary line parallel to the orbitomeatal line. The catheter will usually be inserted into the ventricle at a point 5 cm deep to the cortex and may be inserted as deep as 6.5 cm. Using this technique, the frontal horn of the lateral ventricle can be easily tapped. The landmark required for this technique is readily available in all patients.