MINIMALLY INVASIVE TREATMENT OF IDIOPATHIC SYRINGOMYELIA USING MYRINGOTOMY T-TUBES: A CASE REPORT AND TECHNICAL NOTE.

Syringomyelia is characterized by a fluid-filled cavity within the spinal cord. Expansion of the syrinx often results in the clinical course of progressive neurologic deficit. Surgery for syringomyelia generally aims to treat the underlying cause, if it is known. However, little is known about idiopathic syringomyelia, which requires specific management. In our paper, an alternative, minimally invasive treatment option for large symptomatic idiopathic cervicothoracic syrinx is described and discussed. We present a case of a 44-year-old male without a history of spinal cord trauma, infection, or other pathologic processes, who presented for thoracic pain. Due to progressive pain and left leg paresis, magnetic resonance imaging (MRI) was performed and revealed extensive septated syringomyelia from T5 to T7 and hydromyelia cranially. We applied minimally invasive technique for shunting the idiopathic syrinx into the subarachnoid space using two Richards modified myringotomy T-tubes. Postoperative MRI revealed significant decrease in the syrinx size and clinical six-month follow-up showed improvement of clinical symptoms. This minimally invasive treatment of syringomyelia was found to be an effective method for idiopathic septated syrinx, without evident underlying cause. However, long-term follow-up and more patients are necessary for definitive evaluation of this technique.

Intraoperative visualization of residual tumor: the role of perfusion-weighted imaging in a high-field intraoperative magnetic resonance scanner.

BACKGROUND: High-field, intraoperative magnetic resonance imaging (iMRI) achieves free tumor margins in glioma surgery by involving anatomic neuronavigation and sophisticated functional imaging. OBJECTIVE: To evaluate the role of perfusion-weighted iMRI as an aid to detect residual tumor and to guide its resection. METHODS: Twenty-two patients undergoing intraoperative scanning (in a dual-room 1.5-T magnet setting) during the resection of high-grade gliomas were examined with perfusion-weighted iMRI. The generated relative cerebral blood volume (rCBV) maps were scrutinized for any hot spots indicative of tumor remnants, and region-of-interest analysis was performed. Differences among the rCBV region-of-interest estimates in residual tumor, free tumor margins, and normal white matter were analyzed. Histopathology of the tissue specimens and the neurosurgeon's intraoperative macroscopic estimations were considered the reference standards. RESULTS: In all cases, diagnostic rCBV perfusion maps were generated. Interpretation of perfusion maps demonstrated that gross total resection of gliomas was achieved in 4 of 22 cases (18%), which was macroscopically and histopathologically verified, whereas in 18 of 22 cases (82%), the perfusion-weighted iMRI revealed hot spots indicating subtotal tumor removal. The latter proved to be true in all but 1 case. The receiver-operating characteristic curves of the qualitative visual and quantitative analyses showed excellent sensitivity and specificity rates. Statistical analysis demonstrated statistically significant differences for the mean rCBV and maximum rCBV between residual disease and tumor-free margins (P = .002 for both). CONCLUSION: Perfusion-weighted iMRI may be implemented easily into imaging protocols and may assist the surgeon in detecting residual tumor volume.

The possible role of neuropeptide Y after spontaneous subarachnoid hemorrhage.

OBJECTIVE: Neuropeptide Y (NPY), a highly potent vasoconstrictive neuropeptide, is widely expressed in the human brain, regulating vessel diameter and cerebral blood flow. Earlier studies focusing on the possible role of NPY in the context of aneurismal subarachnoid hemorrhage (SAH) and vasospasm have produced conflicting results. However, despite extensive research efforts, the pathophysiological mechanisms underlying the SAH-related vasospasm and delayed cerebral ischemia (DCI) have not been clarified. We, therefore, attempted to investigate the role of NPY in SAH-induced vasospasm in a larger, well documented patient population utilizing modern analytical tools. We focused on the release of the potent vasoconstrictor NPY in cerebrospinal fluid (CSF) and blood, and its correlation to vasospasm and stroke in the early clinical stage. METHODS: Thirty-seven patients with SAH and a control group consisting of 29 patients were included. Eighteen patients developed stroke, 21 patients met the Doppler sonographical criteria for vasospasm. Twenty-nine patients had aneurysms of the anterior circulation and four patients of the posterior circulation. All patients had ventricular drainage inserted and an arterial catheter. Blood and CSF were drawn daily for NPY analysis during a 10-day interval. RESULTS: The levels of NPY in CSF and plasma were significantly higher after SAH than in the control group (p = 0.001). The vasospasm group showed NPY levels in CSF which continuously ranged above the NPY levels of the non-vasospasm group (p = 0.001). Patients with stroke caused by vasospasm had significantly higher levels of NPY (p = 0.001). DISCUSSION: NPY is released excessively into blood and CSF following SAH. Patients with cerebral infarction caused by vasospasm had significantly higher levels of NPY. Our results indicate a certain role for NPY in the pathophysiology of vasospasm due to SAH and justify further studies in this area of research.

Image-guided lateral suboccipital approach: part 1-individualized landmarks for surgical planning.

OBJECTIVE: Being situated close to the transverse and sigmoid sinus, the asterion has traditionally been viewed as a landmark for surgical approaches to the posterior fossa. Cadaveric studies, however, have shown its variability in relation to underlying anatomic structures. We have used an image-guidance technology to determine the precise anatomic relationship between the asterion and the underlying transverse-sigmoid sinus transition (TST) complex in patients scheduled for posterior fossa surgery. The applicability of three-dimensional (3-D) volumetric image-rendering for presurgical anatomic identification and individualization of a surgical landmark was evaluated. METHODS: One-millimeter computed tomographic slices were combined with venous computed tomographic angiography in 100 patients, allowing for 3-D volumetric image-rendering of the cranial bone and the dural vasculature at the same time. The spatial relationship between the asterion and the TST was recorded bilaterally by using opacity modulation of the bony surface. The location of both the asterion and the TST could be confirmed during surgery in all of these patients. RESULTS: It was possible to accurately visualize the asterion and the sinuses in a single volumetrically rendered 3-D image in more than 90% of the patients. The variability in the anatomic position of the asterion as shown in cadaveric studies was confirmed, providing an individualized landmark for the patients. In this series, the asterion was located from 2 mm medial to 7 mm lateral and from 10 mm inferior to 17 mm superior to the TST, respectively. CONCLUSION: Volumetric image-rendering allows for precise in vivo measurements of anatomic distances in 3-D space. It is also a valuable tool for assessing the validity of traditional surgical landmarks and individualizing them for surgical planning.

Image-guided lateral suboccipital approach: part 2-impact on complication rates and operation times.

OBJECTIVE: Image-guidance systems are widely available for surgical planning and intraoperative navigation. Recently, three-dimensional volumetric image rendering technology that increasingly applies in navigation systems to assist neurosurgical planning, e.g., for cranial base approaches. However, there is no systematic clinical study available that focuses on the impact of this image-guidance technology on outcome parameters in suboccipital craniotomies. METHODS: A total of 200 patients with pathologies located in the cerebellopontine angle were reviewed, 100 of whom underwent volumetric neuronavigation and 100 of whom underwent treatment without intraoperative image guidance. This retrospective study analyzed the impact of image guidance on complication rates (venous sinus injury, venous air embolism, postoperative morbidity caused by venous air embolism) and operation times for the lateral suboccipital craniotomies performed with the patient in the semi-sitting position. RESULT: This study demonstrated a 4% incidence of injury to the transverse-sigmoid sinus complex in the image-guided group compared with a 15% incidence in the non-image-guided group. Venous air embolisms were detected in 8% of the image-guided patients and in 19% of the non-image-guided patients. These differences in terms of complication rates were significant for both venous sinus injury and venous air embolism (P < 0.05). There was no difference in postoperative morbidity secondary to venous air embolism between both groups. The mean time for craniotomy was 21 minutes in the image-guided group and 39 minutes in non-image-guided group (P = 0.036). CONCLUSION: Volumetric image guidance provides fast and reliable three-dimensional visualization of sinus anatomy in the posterior fossa, thereby significantly increasing speed and safety in lateral suboccipital approaches.

Long-term follow-up of patients with pituitary macroadenomas after postoperative radiation therapy: analysis of tumor control and functional outcome.

PURPOSE: Evaluation of long-term tumor control, normalization of hormonal hypersecretion, including incidence and time course of pituitary dysfunction following postoperative radiotherapy of pituitary macroadenomas. PATIENTS AND METHODS: In a retrospective study, the data of 87 patients with pituitary macroadenomas (61 non-secreting adenomas, 26 secreting adenomas) treated between 1984 and 1994 were analyzed. All patients underwent surgery and received postoperative external-beam radiotherapy with a mean dose of 50.4 Gy (range 46-54 Gy). RESULTS: After a follow-up of 15 years the local tumor control rate achieved was 93.0% for non-secreting adenomas and 100% for secreting adenomas, respectively. Normalization of endocrine hypersecretion was noted in 24 of 26 patients (92%). Detailed endocrinological follow-up data were analyzed by an experienced endocrinologist in 77 patients. After a median follow-up of 10.54 years (mean 10.22; range 1.39-20.75 years), in 75 of 77 patients (97%) a hypopituitarism was observed (partial hypopituitarism, n = 28 [36%], panhypopituitarism, n = 47 [61%]), and 68 out of 77 patients (88%) showed evidence of radiotherapy-induced pituitary disorders. The somatotropic function was most commonly affected, followed by gonadal, thyroid and adrenal function. The gonadal axis showed to be the first to be disturbed. 67 patients (87%) required a hormone replacement therapy. CONCLUSION: Radiotherapy after pituitary surgery is highly effective in reducing hormonal hypersecretion and preventing recurrences of pituitary adenomas. However, pituitary insufficiencies are commonly observed after radiotherapy requiring a close follow-up to ensure timely diagnosis of pituitary dysfunction and an early inception of hormone replacement therapy.

Neuronavigational endoscopic endonasal sellar and parasellar surgery using a 2-mm-diameter lens rigid-rod endoscope: a cadaver study.

OBJECTIVE: Most of the endoscopes used for endonasal transsphenoidal surgery use 4-mm diameter lenses. The applicability of a newly developed neuroendoscope with a lens diameter of only 2 mm was tested in endonasal transsphenoidal pituitary surgery. METHODS: The newly developed rigid-rod neuroendoscope with a 2-mm lens and an endoscope with a 4-mm lens were coupled with a navigation system and used for this comparative study. Comparison between the views obtained with these two devices was performed in a model and in formalin-fixed cadaver heads. A pure endonasal approach was used to reach and explore the sellar and parasellar regions. The navigation system was used to locate the same position in both lenses for image comparison. RESULTS: The sellar and parasellar regions could be reached and explored using the new endoscope with the 2-mm lens and an oval-shaped irrigation and suction channel. The visual field appeared to be reduced compared with that of the 4-mm lens. However, this reduction was compensated by greater mobility and easier introduction and maneuvering of the instruments at the sellar level. Reduced image size and brightness were also found using the 2-mm lens compared with the 4-mm lens. These differences could be overcome by increasing the amount of light and enlarging the image but with subsequent reduction in image resolution. CONCLUSION: The small diameter of this neuroendoscope resulted in good maneuverability and maintained a fine quality of vision. Children and patients with small nostrils are good candidates for the use of such a device.

Neuronavigational neuroendoscopic surgery. Frameless free-hand maneuvering of a handy rigid-rod neuroendoscope on visualized three-dimensional computerized image guidance: trajectory to the prepontine cistern in cadaver study.

BACKGROUND: Considering the separate benefits of neuronavigation and neuroendoscopy, neuroendoscopic surgery with the aid of neuronavigation systems will play an increasingly important role in the future. Bearing this in mind, the present research project was conducted to facilitate neuronavigational neuroendoscopic surgery along the pathway to the prepontine cistern using cadaver heads. MATERIALS AND METHODS: A computer-aided, frameless image-guided stereotactic navigation system and a new type of handy rigid-rod neuroendoscope were used. The ideal entry point and the safest trajectory to the prepontine cistern through the foramen of Monro were defined in two formalin-fixed cadaver heads and clinical brain MRI data. Then, maneuvering of the neuroendoscope with the aid of the neuronavigation system was performed. RESULTS: Straight trajectories from the entry point to the prepontine cistern could be designed. For the registration accuracy of the tip of the neuroendoscope, the virtual image registered a mean error distance of 5.42 mm away from the reference point along the axis of vertical line. However, free-hand maneuvering enabled the neuroendoscope to be finely manipulated without damaging brain tissues. Neuroendoscopic anatomical views of the interpeduncular and prepontine cistern were also acquired. CONCLUSION: Interactive use of free-hand maneuvering of the handy rigid-rod neuroendoscope together with frameless neuronavigation systems plot the way to true neuronavigational neuroendoscopic surgery in a safe and reliable manner. This pairing of the most recent technological neurosurgical options with better understanding of neuroendoscopic anatomy enables the neurosurgeon to acquire broader treatment options for central nervous system diseases.

Effects of gamma knife radiosurgery of pituitary adenomas on pituitary function.

OBJECT: The authors undertook a retrospective analysis of the incidence and time course of pituitary insufficiency following gamma knife radiosurgery (GKS) for pituitary adenomas. METHODS: Pituitary adenomas in 92 patients were analyzed. There were 61 hormonally inactive tumors, 18 prolactinomas, and nine somatotropic and four adrenocorticotropic adenomas. The mean tumor volume was 3.8 cm3 (range 0.2-14.6 cm3). The mean prescription dose was 15 Gy. The mean prescription isodose was 50.7%. The mean follow-up time was 4.6 years (range 1.2-10 years). The following new or deteriorating insufficiencies that did not require treatment were recorded for the different pituitary axes: follicle-stimulating hormone (FSH)/ luteinizing hormone (LH) 19 (20.6%), thyroid-stimulating hormone (TSH) 32 (34.8%), adrenocorticotropic hormone (ACTH) 10 (10.9%), and growth hormone (GH) 26 (28.3%). For new insufficiencies or deterioration requiring replacement therapy, the figures were as follows: FSH/LH 20 (21.7%), TSH 22 (23.9%), ACTH eight (8.7%), and GH 12 (13%). Spot dosimetry was performed in 59 patients in the hypothalamic region, the pituitary gland, and pituitary stalk. The pituitary stalks in patients with deterioration of pituitary function received a statistically higher dosage of radiation, 7.7 +/- 3.7 Gy compared with 5.5 +/- 3 Gy (p = 0.03). CONCLUSIONS: The function of the residual normal pituitary gland is less affected following GKS of pituitary adenomas than after fractionated radiotherapy. Nonetheless, increased attention needs to be exercised to reduce the dose to the stalk and pituitary gland to minimize the incidence of these complications.