Outcome of Anterior Lumbar Interbody Fusion: A Retrospective Study of Clinical and Radiologic Parameters.

OBJECTIVE: This study critically evaluates the long-term results of standalone anterior lumbar interbody fusion (ALIF), without use of rhBMP-2, as a therapeutic option for symptomatic patients with degenerative disc disease (DDD). Furthermore, this study intends to identify predictive parameters for anterior lumbar interbody fusion outcome. METHODS: A retrospective cohort study with additional telephone interview to obtain missing data was performed. All patients who underwent an L4-L5 or L5-S1 ALIF-procedure, or both, in the period between 2006 and 2011 were identified. The medical files of 123 patients with 154 fusion levels were reviewed. All patients were contacted by telephone to gather supplementary and missing information. Pain and functionality scores (Visual Analogue Scale [VAS] and Oswestry Disability Index [ODI]), radiologic (intervertebral disc height, Modic and Pfirrmann classifications), and different clinical parameters were gathered. RESULTS: The mean age of the population at surgery was 46.2 years. Overall, 59 female and 64 male patients were included in the study. The mean VAS score for back and leg pain improved significantly (P < 0.001) with 5 and 4.4 points respectively at 3-year follow-up. Modic-type I changes are associated with a better improvement in VAS score for back pain (P = 0.026), Pfirrmann-grades IV and V and an intervertebral disc height of less than 5 mm are associated with a better improvement in leg pain (respective P-values: 0.045 and 0.033). Overall, 89% of patients would reconsider the surgical intervention. CONCLUSIONS: The ALIF technique is a durable treatment option for patients with DDD. This study suggests different predictive parameters for treatment outcome.

Vagus Nerve Stimulator Placement in Dogs: Surgical Implantation Technique, Complications, Long-Term Follow-Up, and Practical Considerations.

OBJECTIVE: To describe a modified implantation procedure of a vagus nerve stimulation (VNS) device in dogs and to report short- and long-term complications. STUDY DESIGN: Descriptive, experimental study. ANIMALS: Healthy, adult Beagle dogs (n = 10). METHODS: A VNS Therapy(®) System was implanted in the left cervical region of anesthetized dogs. During and within 48 hours after surgery, electrocardiography (ECG) and impedance testing of the system were performed. Dogs were monitored daily and the impedance of the system was determined regularly until VNS devices were surgically removed 3 years after implantation. RESULTS: The implantation procedure was successful in all dogs without intraoperative complications. ECG monitoring and impedance tests were within normal limits during and within 48 hours after surgery. Postoperative seroma formation was common (70%). One dog developed an irreversible Horner's syndrome leading to removal of the device 5 months after implantation. Another dog developed trauma-induced damage of the lead requiring surgical revision. The device could be safely removed in all dogs; however, electrodes were left in place to avoid nerve damage. At removal, the anchor tether was dislodged in 40% of dogs and the lead was twisted in 50% of dogs. CONCLUSION: Implantation of a VNS Therapy(®) System is safe and feasible in dogs; however, seroma formation, twisting of the lead, and dislodgement of the anchor tether were common. Practical improvements in the technique include stable device placement, use of a compression bandage, and exercise restriction. Regular evaluation of lead impedance is important, as altered values can indicate serious complications.

The use of the trendelenburg position in the surgical treatment of extreme cerebellar slump.

BACKGROUND: State-of-the-art treatment for Chiari Malformation I (CM-I) consists of decompression by posterior fossa craniectomy. A rare but severe complication that develops over months to years after this procedure is cerebellar slump. Treatment options for this condition are limited. We present a new and promising approach to treat this rare condition. METHODS: The patients were placed in the Trendelenburg position to facilitate ascent of the cerebellum. After almost complete dissolution of neurologic symptoms, surgical reconstruction was performed by tonsillar resection and the creation of a new structural support using a bone graft. RESULTS: Both patients experienced good clinical and morphological outcomes immediately after surgery, and for two years thereafter. CONCLUSIONS: Neurological symptoms related to cerebellar or brainstem slump can be adequately reversed by placing the patient in the Trendelenburg position. After uneventful gravitational reversal of the slump, safe surgical reconstruction of the cerebellar support can be performed to securely preserve the anatomical reversal.

Endoscopic Treatment of Temporal Arachnoid Cysts in 34 Patients.

INTRODUCTION: Arachnoid cysts are lesions present in 1% of the population and usually found in the temporal fossa. Clinical and radiologic presentations can differ greatly. Despite intensive research, it is still debatable which patients will benefit from surgery. OBJECTIVE: This study aims to investigate the pretreatment parameters influencing the outcome after neuroendoscopic treatment of temporal arachnoid cysts. MATERIALS AND METHODS: A retrospective analysis of 34 patients who underwent an endoscopic fenestration of a temporal arachnoid cyst between July 1991 and December 2013 was performed. RESULTS: In symptomatic patients, there was a clinical improvement in 76.4% of cases. The best results were found in treating symptoms related to intracranial hypertension, acute neurologic defects, and macrocrania. Patients with temporal lobe epilepsy improved after cyst fenestration in 33.3% of cases. Behavioral problems and psychomotor retardation remained largely unchanged. Patients with a complex neurologic presentation, often from a congenital syndrome and combined with an intellectual disability, had the least benefit from endoscopic surgery. Radiologic follow-up showed a cyst volume decrease in 91.2% of cases. Complications were present in 29.4%, but were mostly minor and transient. CONCLUSION: This study demonstrates that patients with symptoms related to intracranial hypertension, acute neurologic deficits, and macrocrania have the best postoperative outcome. Also, patients with ipsilateral temporal lobe epilepsy seem to be good candidates for endoscopic arachnoid cyst fenestrations. In complex neurologic disorders without one of the previously mentioned symptoms, endoscopy remains less successful.

Regional brain perfusion changes during standard and microburst vagus nerve stimulation in dogs.

PURPOSE: Vagus nerve stimulation (VNS) is an effective adjunctive treatment for refractory epilepsy in humans, but its mechanism of action (MOA) and optimal stimulation parameters are still unknown. Functional neuroimaging studies could provide better insight into the brain structures involved in the activity of VNS, but have not yet been described in dogs. The aim of this study was to investigate the effect of acute VNS on the regional cerebral blood flow (rCBF) in dogs using micro-SPECT (µ-SPECT). Additionally, a novel stimulation paradigm (microburst VNS) was used and compared with standard VNS. METHODS: A VNS Therapy System was implanted in ten Beagle dogs. µ-SPECT was performed after sham, standard and microburst VNS in a randomized, cross-over study. Nineteen volumes of interest (VOIs) were semi-quantitatively analysed and perfusion indices (PIs) were calculated. Furthermore, a rostro-caudal gradient (R-C), an asymmetry index (AI) and a cortical-subcortical index (Co-SCo) were determined. The SPECT results after standard and microburst VNS were compared pairwise with sham stimulation. RESULTS: Acute standard VNS did not cause significant rCBF alterations. Acute microburst VNS caused a significant hypoperfusion in the left frontal lobe (P=0.023) and in the right parietal lobe (P=0.035). Both stimulation paradigms did not cause changes in R-C, AI nor Co-SCo. CONCLUSIONS: Microburst VNS is more potent than standard VNS to modulate the rCBF in the dog. Our results promote further research towards the antiepileptic effect of microburst VNS in dogs and humans.

A novel design for steerable instruments based on laser-cut nitinol.

OBJECTIVE: Omnidirectional articulated instruments enhance dexterity. In neurosurgery, for example, the simultaneous use of 2 instruments through the same endoscopic shaft remains a difficult feat. It is, however, very challenging to manufacture steerable instruments of the requisite small diameter. We present a new technique to produce such instruments by means of laser cutting. Only 3 coaxial tubes are used. The middle tube has a cutting pattern that allows the steering forces to be transmitted from the proximal to the distal end. In this way the steering part is concealed in the wall of the tube. Large diameter articulated instruments such as for laparoscopy might benefit from the excellent tip stability provided by the same economical technology. METHOD: Coaxial nitinol tubes are laser-cut with a Rofin Stent Cutter in a specific pattern. The 3 tubes are assembled by sliding them over one another, forming a single composite tube. In a surgical simulator, the neurosurgical microinstruments and laparoscopic needle drivers were evaluated on surgical convenience. RESULTS: Simultaneous use of 2 neurosurgical instruments (1.5 mm diameter) through the same endoscopic shaft proved to be very intuitive. The tip of the steerable laparoscopic instruments (10 mm diameter) could resist a lateral force of more than 20 N. The angle of motion for either instrument was at least 70° in any direction. CONCLUSIONS: A new design for steerable endoscopic instruments is presented. It allows the construction in a range from microinstruments to 10-mm laparoscopic devices with excellent tip stability.

Treatment of cystic craniopharyngioma by endocavitary instillation of yttrium9° radioisotope--still a valuable treatment option.

Craniopharyngiomas are a challenging pathology in neurosurgery because of their anatomic localization in the (supra)sellar region and their contact with diencephalic structures around the third ventricle. Among the different treatment modalities, stereotactic intracavitary treatment by instillation of yttrium9° radioisotope is a minimally invasive technique of particular use in the treatment of cystic or partially cystic craniopharyngiomas. It can be performed under local anesthesia during a short hospitalization and has a long-lasting effect. This treatment can be repeated or used in combination with other treatment modalities such as microsurgery, endoscopy, conformal external radiation therapy, or stereotactic radiosurgery. Thus, this old and perhaps almost forgotten treatment option is still valuable in the treatment of cystic craniopharyngiomas.

Endoscopic coagulation of choroid plexus hyperplasia.

Hydrocephalus is a clinical disorder resulting from an imbalance between the production of CSF and its resorption, of which the latter is mostly a disadvantage. In rare cases of choroid plexus papilloma or carcinoma, hydrocephalus is due to an overproduction of CSF. Choroid plexus hyperplasia (CPH) is a distinct clinicopathological entity in which the enlarged choroid plexus produces large amounts of CSF. Historically, patients with CPH were treated by shunt procedures or by microsurgical removal of the choroid plexus, which is associated with a high complication rate. In this paper the authors show that endoscopic plexus coagulation can result in restoring the equilibrium of the intracranial fluid volumes, resulting in shunt independency. In this way, both the shunt-related complications and the bleeding risks of microsurgical plexectomy are avoided. In instances of hydrocephalus, thorough efforts should be made to demonstrate the underlying pathophysiology to choose the optimal treatment, of which shunt procedures should receive the least priority.

Surgical treatment of disk-associated wobbler syndrome by a distractable vertebral titanium cage in seven dogs.

OBJECTIVE: To evaluate a distractable titanium cage for the treatment of disk-associated wobbler syndrome (DAWS). STUDY DESIGN: Prospective study. ANIMALS: Dogs (n = 7) with DAWS. METHODS: After total discectomy of C5-C6 and C6-C7, the median part of the vertebral body of C6 was removed with preservation of the lateral walls and dorsal cortex. The removed cancellous bone was collected. The implant was placed in the bony defect of C6. After placement, the titanium cage was distracted and affixed by 4 screws. Finally, the implant was filled and covered with cancellous bone. Dogs had follow-up examinations at 1, 3, 6, 12, and 24 months. Six months after surgery, cervical radiographs and computed tomography (CT) were performed. RESULTS: Although no intraoperative complications occurred, correct placement of the cage was technically challenging. Revision surgery was necessary in 2 dogs because of implant loosening and aggravation of vertebral tilting. All dogs improved after discharge from the hospital. In 1 dog, recurrence of clinical signs caused by articular facet proliferation at an adjacent intervertebral disk space occurred. Radiographs at 6 months demonstrated cage subsidence in 4 dogs. In all dogs, CT was suggestive for fusion of the bone graft with the vertebral body. CONCLUSIONS: Although results are promising, technical adaptations will be necessary to make this specific surgical technique, designed for humans, suitable for routine use in dogs.

Computed tomographic analysis of the quality of trunk muscles in asymptomatic and symptomatic lumbar discectomy patients.

BACKGROUND: No consensus exists on how rehabilitation programs for lumbar discectomy patients with persistent complaints after surgery should be composed. A better understanding of normal and abnormal postoperative trunk muscle condition might help direct the treatment goals. METHODS: A three-dimensional CT scan of the lumbar spine was obtained in 18 symptomatic and 18 asymptomatic patients who had undergone a lumbar discectomy 42 months to 83 months (median 63 months) previously. The psoas muscle (PS), the paraspinal muscle mass (PA) and the multifidus muscle (MF) were outlined at the L3, L4 and L5 level. Of these muscles, fat free Cross Sectional Area (CSA) and fat CSA were determined. CSA of the lumbar erector spinae (LES = longissimus thoracis + iliocostalis lumborum) was calculated by subtracting MF CSA from PA CSA. Mean muscle CSA of the left and right sides was calculated at each level. To normalize the data for interpersonal comparison, the mean CSA was divided by the CSA of the L3 vertebral body (mCSA = normalized fat-free muscle CSA; fCSA = normalized fat CSA). Differences in CSA between the pain group and the pain free group were examined using a General Linear Model (GLM). Three levels were examined to investigate the possible role of the level of operation. RESULTS: In lumbar discectomy patients with pain, the mCSA of the MF was significantly smaller than in pain-free subjects (p = 0.009) independently of the level. The mCSA of the LES was significantly smaller in pain patients, but only on the L3 slice (p = 0.018). No significant difference in mCSA of the PS was found between pain patients and pain-free patients (p = 0.462). The fCSA of the MF (p = 0.186) and of the LES (p = 0.256) were not significantly different between both populations. However, the fCSA of the PS was significantly larger in pain patients than in pain-free patients. (p = 0.012).The level of operation was never a significant factor. CONCLUSIONS: CT comparison of MF, LES and PS muscle condition between lumbar discectomy patients without pain and patients with protracted postoperative pain showed a smaller fat-free muscle CSA of the MF at all levels examined, a smaller fat- free muscle CSA of the LES at the L3 level, and more fat in the PS in patients with pain. The level of operation was not found to be of importance. The present results suggest a general lumbar muscle dysfunction in the pain group, in particular of the deep stabilizing muscle system.

Surgical treatment of a canine intranasal meningoencephalocele.

OBJECTIVE: To report the clinical signs, diagnosis, and surgical treatment of an intranasal meningoencephalocele in a dog. STUDY DESIGN: Case report. ANIMAL: Female Border collie, 5 months old. METHODS: A right intranasal meningoencephalocele was identified by computed tomography and magnetic resonance imaging. RESULTS: The lesion was approached by a modified transfrontal craniotomy. Surgical closure of the defect at the level of the cribriform plate and removal of extruded brain tissue resulted in regression of lacrimation and coincided with absence of seizuring. Treatment with phenobarbital was gradually reduced and stopped at 7 months after surgery. At 28 months the dog remained free of seizures. CONCLUSION: Meningoencephalocele, although rare, can cause seizures in dogs and can be treated surgically. CLINICAL RELEVANCE: A transfrontal craniotomy with excision of the meningoencephalocele and closure of the defect can be an effective treatment for an intranasal meningoencephalocele in dogs.

Migration of pump for intrathecal drug delivery into the peritoneal cavity. Case report.

BACKGROUND: We report on a patient in whom a subfascially implanted pump for the intrathecal delivery of baclofen spontaneously migrated into the peritoneal cavity. CASE DESCRIPTION: A 54-year-old male patient presented with a refilling problem of a drug pump that had been implanted 16 months earlier subfascially through a right-sided incision 10 cm below the costal margin. Because we were unable to refill the pump even under fluoroscopy, we presumed a backward turning of the pump. At exploration, we found that the deeper part of the pocket had spontaneously eroded and had caused the migration of the pump into the peritoneal cavity. The peritoneum and the abdominal wall were closed and the pump was placed in a subcutaneous pouch. We suppose that the migration of the pump was due to its particular implantation site with the lower extent of the device at or below the level of the linea semilunaris. Below this line, the aponeuroses of all 3 lateral abdominal muscles pass in front of the rectus muscle, leaving only the transversal fascia underneath the rectus, which is not a solid layer. Not considering this anatomical detail may facilitate the inward migration of implanted material. CONCLUSION: When creating a pocket for subfascial implantation, a high subcostal incision should be used so that the lower extent of the pocket will still be above the level of the linea semilunaris, hence ensuring a strong fascial layer between the pump and the peritoneum.

Brain activation associated with deep brain stimulation causing dissociation in a patient with Tourette's syndrome.

Dissociation involves a disruption in the integrated functions of consciousness, memory, identity, or perception of the environment. Attempts at localizing dissociative responses have yielded contradictory results regarding brain activation, laterality, and regional involvement. Here, we used a single-day split-dose activation paradigm with single photon emission computed tomography and 99m-Tc ethylcysteinatedimer as a brain perfusion tracer in a patient with Tourette's syndrome undergoing bilateral high-frequency thalamic stimulation for the treatment of tics who developed an alternate personality state during right thalamic stimulation. We documented increased regional cerebral blood flow in bilateral prefrontal and left temporal brain areas during the alternate identity state. We conclude that our findings support the temporal lobe as well as the frontolimbic disconnection hypotheses of dissociation.

Deep brain stimulation in patients with refractory temporal lobe epilepsy.

PURPOSE: This pilot study prospectively evaluated the efficacy of long-term deep brain stimulation (DBS) in medial temporal lobe (MTL) structures in patients with MTL epilepsy. METHODS: Twelve consecutive patients with refractory MTL epilepsy were included in this study. The protocol included invasive video-EEG monitoring for ictal-onset localization and evaluation for subsequent stimulation of the ictal-onset zone. Side effects and changes in seizure frequency were carefully monitored. RESULTS: Ten of 12 patients underwent long-term MTL DBS. Two of 12 patients underwent selective amygdalohippocampectomy. After mean follow-up of 31 months (range, 12-52 months), one of 10 stimulated patients are seizure free (>1 year), one of 10 patients had a >90% reduction in seizure frequency; five of 10 patients had a seizure-frequency reduction of > or =50%; two of 10 patients had a seizure-frequency reduction of 30-49%; and one of 10 patients was a nonresponder. None of the patients reported side effects. In one patient, MRI showed asymptomatic intracranial hemorrhages along the trajectory of the DBS electrodes. None of the patients showed changes in clinical neurological testing. Patients who underwent selective amygdalohippocampectomy are seizure-free (>1 year), AEDs are unchanged, and no side effects have occurred. CONCLUSIONS: This open pilot study demonstrates the potential efficacy of long-term DBS in MTL structures that should now be further confirmed by multicenter randomized controlled trials.

Comparison of postural control in unilateral stance between healthy controls and lumbar discectomy patients with and without pain.

MAIN PROBLEM: Previous studies have demonstrated that sciatica patients have poorer postural control than healthy controls and that postural control remains unchanged 3 months after lumbar discectomy in sciatica patients. The aims of the current study were to investigate whether static balance control recovers in pain-free discectomy patients long-term after lumbar discectomy. Next is to determine whether static balance responses of asymptomatic and symptomatic lumbar discectomy patients differed from each other and from healthy controls. In addition, the influence of the extent of disc resection (unilateral/bilateral removal) and the side of operation on static balance control were investigated. METHODS: Fifteen pain-free lumbar discectomy patients, 23 lumbar discectomy patients with residual pain and 72 controls performed unilateral stance tasks with eyes open and eyes closed on a force plate were taken up for the investigation. Three repetitions of a 10 s unilateral stance test were performed on each leg. Postural sway was determined. Patients were divided into three age groups. RESULTS: In the eyes open condition, there was no significant difference between postural sway of pain-free lumbar discectomy patients and controls (P=0.68), whereas balance of patients with pain was significantly worse than in controls (P=0.003). In the eyes closed condition, the sway in both groups of lumbar discectomy patients was significantly worse than in controls (pain-free P=0.009/painful P<0.001). No significant differences were found in postural sway between patients with unilateral and bilateral disc resection. In unilateral stance on the leg of the operated side, centre of gravity sway was not significantly different in the eyes open condition compared to the eyes closed condition, whereas in stance on the leg of the non-operated side, postural sway was significantly lower in the eyes open condition compared to the eyes closed condition. In both conditions, postural sway in the age group of 50-65 years was significantly higher than in the age groups of 30-39 years (eyes open P=0.005; eyes closed P<0.001) and 40-49 years (eyes open P=0.002; eyes closed P=0.006). There was no significant difference between the age group of 30-39 years and the age group of 40-49 years (P=0.51). CONCLUSION: As for long-term following lumbar discectomy, there is no complete recovery of postural control. Patients seem to develop visual compensation mechanisms for underlying sensory-motor deficits, which are, however, sufficient in case of pain relief only. Further study is needed to determine the cause of the balance disturbances in lumbar discectomy patients.

Long-term effects of bilateral subthalamic nucleus stimulation in advanced Parkinson disease: a four year follow-up study.

In this study we aimed to investigate the effects of bilateral STN HFS in patients with advanced Parkinson disease (PD) at long-term, with a minimum follow-up of 4 years. Twenty patients (15 men, five women) were included, with a mean age of 60.9+/-8.1 years. Surgery was performed under local anesthesia. The target was defined on computerized tomography (CT). At 3 months, significant improvements were found on the total Unified Parkinson disease rating scale (UPDRS) III (motor) score, in the medication. off (from 42.3+/-9.3 to 19.5+/-6.4), as well as the medication on (from 18.6+/-12.1 to 10.1+/-5.9) phase. The UPDRS IVa (dyskinesias) and IVb (motor fluctuations) scores decreased significantly. At long-term follow-up, there were still significant improvements on the total UPDRS III motor score (from 42.3+/-9.3 to 24.2+/-13.2), as well as in all motor subscores, in the off phase, during stimulation. In the on phase, the only significant improvement was seen for rigidity. Complications included hypomania to mania in four patients. Our results indicate that HFS STN results in long-lasting improvement of the motor symptoms, ADL activities and functional performance in patients suffering from advanced PD. The stimulation induced behavioural changes need special consideration.

Vagus nerve stimulation for refractory epilepsy: a transatlantic experience.

Vagus nerve stimulation (VNS) is an alternative treatment for medically or surgically refractory epilepsy. The long-term efficacy and safety of VNS were evaluated in a large patient series at Ghent University Hospital and Dartmouth-Hitchcock Medical Center. Between March 1995 and February 2003, seizure frequency and type as well as prescribed antiepileptic drugs and side effects were prospectively assessed in 131 patients treated with VNS in either center. Patients with a minimum follow-up duration of 6 months were included in the efficacy and safety analysis. A total of 118 of 131 implanted patients had a minimum postimplantation follow-up period of 6 months (mean, 33 months). The mean age of these patients was 32 years and the mean duration of refractory epilepsy was 22 years. The mean reduction in monthly seizure frequency in all patients was 55% (range, 0-100; SD = 31.6). Seven percent of patients were free of seizures with impaired consciousness, 50% of patients had a seizure frequency reduction of more than 50%, and 21% of patients were nonresponders. Fifteen patients reported stimulation-related side effects such as hoarseness or gagging. In a large patient series from two geographically distinct epilepsy centers located in two different continents, VNS proved to be efficacious and safe during long-term follow-up.

Primary resected meningiomas: relapses and proliferation markers.

UNLABELLED: Relapses of meningiomas are a well known phenomenon during follow-up. The significance of sex, age, surgical treatment and mitotic frequency with regard to relapses are still a matter of debate. PATIENTS AND METHODS: The study included 125 meningioma patients who underwent surgical intervention between 1986 and 1997 They were in follow-up for 3, 5, 10 and 15 years; they were grouped as "stable" or "relapsing" tumours. The follow-up was based on magnetic resonance image (MRI) and tomodensitometry (TDM). The labelling index for Ki67 and PCNA (proliferation markers) was scored at resection. Risk factors for relapse were reviewed using univariate analysis and Cox hazards model. RESULTS: One hundred and twenty-five patients were under medical control of whom 26 showed a relapse. Among them 25 arose from subtotal resected tumours and 1 was a recurrence. Relapses comprised 16 females and 10 males. Tumour relapses at 3,5,10 and 15 years were, respectively, 8.8%, 13.6%, 17.6% and 20.8%. Proliferation markers, at group level, were statistically significantly different to distinguish stable from relapsing and malignant from benign meningiomas. Factors significantly associated with tumour relapse in univariate analysis were incomplete resection, histopathology and proliferation markers. In multivariate analysis the proliferation markers and incomplete resection were the only significant risk factors (p<0.05) for relapse. CONCLUSION: To avoid relapses of meningiomas, total resection is recommended. The resection type and proliferation markers are predictive factors for tumour relapse. The proliferation markers cannot be applied at the individual level.

Suboccipital craniectomy, dorsal laminectomy of C1, durotomy and dural graft placement as a treatment for syringohydromyelia with cerebellar tonsil herniation in Cavalier King Charles spaniels.

OBJECTIVE: To evaluate retrospectively the efficacy of the suboccipital craniectomy and dorsal laminectomy of C1 with durotomy and placement of a dural graft for treatment of syringohydromyelia (SHM) because of cerebellar tonsil herniation in Cavalier King Charles spaniels (CKCS). This technique is used with great success in human medicine. STUDY DESIGN: Four CKCS diagnosed by Magnetic resonance imaging (MRI) of SHM because of cerebellar tonsil herniation and not responsive to medical therapy underwent a suboccipital craniectomy and dorsal laminectomy of C1 (2 dogs) and of C1 and partial C2 (2 dogs) with durotomy and placement of a dural graft. Three dogs were evaluated neurologically 24 hours, 1 month, and 3 months postoperatively and evaluations were compared with preoperative neurological examination. Repeat MRI took place 3 months postoperatively. RESULTS: Neurological examinations showed neither improvement nor progression of clinical signs 3 months postoperatively. MRI showed no regression of syrinx size 3 months postoperatively. CONCLUSION: Improvement was not seen. Given the progressive nature of the disorder, evaluation over a longer period of time is necessary to detect if progression has stopped. Some modification to the surgical technique is needed to accomplish the same results as in human medicine. A study of a larger population is needed to attain more reliable information. CLINICAL RELEVANCE: Suboccipital craniectomy and dorsal laminectomy of C1 with durotomy and placement of a dural graft is a feasible technique in CKCS, but needs some modification to accomplish the same results as in human medicine.

Lateralized effects of subthalamic nucleus stimulation on different aspects of speech in Parkinson's disease.

In this report, we have analyzed the effects of left and right STN stimulation separately on different aspects of speech. Significant differences were found between left and right stimulation. It appears that selective left-sided stimulation has a profoundly negative effect on prosody, articulation and hence intelligibility. Right-sided stimulation does not display this side-effect. There is no significant difference in speech characteristics between bilateral stimulation on and off. We suggest that a balanced tuning of bilateral basal ganglia networks is necessary for speech, and that the left circuit is probably dominant.