Surgical management of Chiari II malformation: a systematic review of literature.

PURPOSE: Chiari II malformation (CM-II) is a congenital malformation of the posterior fossa associated with myelomeningocele. Of the symptomatic patients, 10-33% require surgical treatment. To this date, there is not a consensus about the best surgical technique, and whether to do duroplasty. METHODS: A literature search of the PubMed database and crossed references was performed, per PRISMA guidelines. Data regarding demographic features, extent of cervicomedullary deformity, clinical presentation, surgical techniques, and clinical outcomes were extracted. Pearson's chi-squared test was applied. The p-values under 0.05 were considered statistically significant. RESULTS: Twenty studies (N = 330) were analyzed. C3 and C4 levels represented 56.4% of the lowest tonsil displacement. The most reported symptom was dysphagia/swallowing dysfunction (53.8%). Suboccipital craniectomy (SOC) and cervical spine expansion (CSE) with duroplasty were the most reported technique. Dural augmentation was performed in 57.4% of the patients. After surgery, 59.6% observed an improvement in symptoms and quality of life, 12.5% were unchanged, and 27.8% had a worsened clinical status. The mortality rate was 2.5% during the first month after surgery, and 17.4% at the last follow-up evaluation. Patients who underwent CSE presented a better clinical outcome (p = 0.002). The SOC procedure could not be correlated with symptom improvement (p = 0.06). CONCLUSION: CM-II is associated with high morbidity and mortality. An early onset symptomatic CM-II demands intervention, which provided an improvement of outcome in most patients included in this review. The best surgical technique and the exact effect of the surgical management of CM-II on mortality are not yet clear.

Induction of Ticlike Involuntary Movements in Rats by Striatotomy and Subsequent Neurochemical Sensitization.

OBJECTIVE: It has been proposed that Tourette syndrome is associated with dysfunction in widespread cortical areas and globus pallidus externus hyperactivity secondary to dopaminergic hyperactivity and serotonergic/dynorphinergic hypoactivity. The main objective of this study was to test this hypothesis by developing an animal model of Tourette syndrome via striatotomy, followed by administration of drugs that mimic the neurotransmitter environment, so as to induce globus pallidus externus hyperactivity. METHODS: Rats were assigned to 3 groups: stereotactic striatotomy (STT) and striatal sham -lesion (SHAM) groups, treated with anterior and posterior striatum procedures in both hemispheres, and a group of nonoperated animals (NAIVE). Postoperatively, all rodents were blindly administered 3 drug protocols: levodopa/benserazide; levodopa/benserazide/ergotamine/naloxone (MIX); and saline. The animals were filmed at the peak action of these drugs. The videos were evaluated by a single blinded researcher. RESULTS: Six types of involuntary movements (IMs) were observed: cephalic, trunk jerks, oromandibular, forepaw jerks, dystonic, and locomotive. The number of animals with IM and the mean number of IM after both levodopa/benserazide and MIX was significantly higher in the STT compared with the SHAM and NAIVE groups. In the SHAM and NAIVE, MIX was superior to levodopa/benserazide in the induction of IM. In the STT, MIX was superior to levodopa/benserazide in the induction of trunk jerks. Appendicular IM were more common after posterior than after anterior striatotomy. CONCLUSIONS: These results show that striatotomy, followed by administration of levodopa/benserazide alone or associated with ergotamine and naloxone, is efficacious in inducing IM, supporting the hypothesis that led to this study.

Accessing the Anterior Mesencephalic Zone: Orbitozygomatic Versus Subtemporal Approach.

BACKGROUND: Despite the latest developments in microsurgery, electrophysiological monitoring, and neuroimaging, the surgical management of intrinsic brainstem lesions remains challenging. Several safe entry points have been described to access the different surfaces of the brainstem. Knowledge of this entry zone anatomy is critical to performing a safe and less morbid approach. To access the anterior midbrain surface, a well-known entry point is the anterior mesencephalic (AM) zone. Our aim was to quantify surgical AM zone exposure through the orbitozygomatic (OZ) and subtemporal (ST) approaches. We also analyzed the angular exposure along the horizontal and vertical axis angles for the AM zone. METHODS: Ten cadaveric heads were dissected using the OZ and ST approaches for anterior midbrain surface exposure. A neuronavigation system was used to determine the 3-dimensional coordinates. The area of surgical exposure, angular exposure, and anatomical limits of each craniotomy were evaluated and determined using software analysis and compared for intersection areas and AM safe zone exposure. RESULTS: The median surgical exposure was 164.7 ± 43.6 mm2 for OZ and 369.8 ± 70.1 mm2 for ST (P = 0.001). The vertical angular exposure was 37.7° ± 9.92° for the OZ and 18.4° ± 2.8° for the ST opening (P < 0.001). The horizontal angular exposure to the AM zone was 37.9° ± 7.3° for the OZ and 47.0° ± 3.2° for the ST opening (P = 0.002). CONCLUSIONS: Although the OZ craniotomy offers reduced surgical exposure, it provides a better trajectory to the AM zone compared with the ST approach.

Hyperhomocysteinemia as a Risk Factor for Intracranial Aneurysms: A Case-Control Study.

OBJECTIVE: Homocysteine, an amino acid derived from methionine metabolism, has gained great importance as an important risk factor for cardiovascular diseases as the result of its thrombogenic properties and endothelial injury association. However, its role in the etiology and screening of intracranial aneurysms (IAs) has not been well studied. We aimed to test the hypothesis of a positive association between hyperhomocysteinemia (HHcy) and IAs. METHODS: A case-control study was performed at a vascular neurosurgery unit in Brazil between 2016 and 2017. In total, 180 patients were included: 142 patients with previous IAs (case group) and 38 patients with a previous diagnosis of arteriovenous malformation and no aneurysms on imaging evaluation (control group). HHcy was defined as homocysteine levels greater than 15 µmol/L. Multivariate models were designed to adjust for potential confounders: age, sex, hypertension, dyslipidemia, and smoker status. RESULTS: The case group was older (56.3 ± 12.6 years vs. 40.9 ± 14.0 years, P < 0.001) and had a greater prevalence of women (76.1% vs. 55.3%, P = 0.012), as well as hypertension (45.1% vs. 2.6%, P < 0.001), dyslipidemia (60.6% vs. 10.5%, P = 0.001), and smokers (41.5% vs. 0.0%, P < 0.001). Median homocysteine in the cases was similar to the controls (10.5 µmol/L [8.3-14.0] vs. 10.7 µmol/L [8.2-13.3], respectively, P = 0.450). There was a trend toward greater HHcy prevalence in the case group (20.4% vs. 7.9%, P = 0.073). HHcy was associated with greater age, male sex, hypertension, and smoking status. After multivariate adjustment, HHcy had no association with IAs (odds ratio 1.34, 95% confidence interval 0.30-5.97, P = 0.703). CONCLUSIONS: No association was found between HHcy and IAs.

Reversible ventriculoperitoneal shunt dysfunction and chronic constipation: case report.

Constipation can cause transient malfunction of the ventriculoperitoneal shunt (VPS). Patients with myelomeningocele or cerebral palsy are often diagnosed with hydrocephalus and constipation due to neurogenic bowel. These patients are more prone to VPS dysfunction, often requiring surgical revision. The authors report the case of a 6-year-old girl with a VPS that had been implanted due to hydrocephalus secondary to myelomeningocele. The patient was brought to the emergency department with intermittent headache, vomiting, constipation, and abdominal distension and pain. A CT scan revealed ventricular dilatation and radiography of the abdomen showed bowel loop distension. After a Fleet enema and digital maneuvers, her abdominal distension and symptoms improved. A CT scan obtained 24 hours later showed a reduction in ventricular size. The mechanism by which constipation can lead to VPS malfunction can be traced to indirect increases of intraabdominal pressure and direct obstruction of the catheter by distended intestinal loops. Treating constipation can restore the free circulation of the CSF and avoid surgical intervention. Careful neurological monitoring of these patients is essential, because some measures used to treat constipation can increase intracranial pressure. The objective of this report was to highlight constipation as a possible cause of transient VPS malfunction, thereby avoiding unnecessary surgical revisions, to which children with hydrocephalus are frequently submitted.

Chordoid glioma: Case report and review of the literature.

INTRODUCTION: Chordoid glioma is a rare low-grade brain tumor originating from the anterior wall of the third ventricle. CASE PRESENTATION: A 13-year-old female with progressive intermittent holocranial headaches and a diagnosis of chordoid glioma underwent tumor resection in our neuro-oncology unit. DISCUSSION: We review all 79 cases of chordoid glioma reported in the literature so far, focusing on the diagnostic criteria, treatment options and prognosis. CONCLUSION: Efficient treatment of chordoid glioma depends upon radical surgical resection. Based on the reviewed data, which showed high morbi-mortality rates for this kind of tumor, we recommend a more conservative treatment approach.

Pathophysiology of the constant burning, tingling element of neuropathic pain: a new hypothesis.

Neuropathic pain (NPP) presents itself with at least one of the following elements: constant, intermittent and evoked pain. The pathophysiology of NPP is still controversial, in especial of its constant element, the focus of this study. Many hypotheses have been proposed in an attempt to explain it, but none of them seems to account for the various aspects of the constant element of NPP. Under the phylogenetic perspective, it is postulated, the pain may be classified into two categories: paleopain, present in inferior animals, poorly localized, transmitted by the medial pain system pathways, and neopain, conducted by the lateral pain system pathways, very well localized, described in terms suggestive of tissue damage and present in superior animals. We believe that, in humans, under physiological circumstances, the expression of the paleopain was completely abolished. It is proposed that it is due to the tonic inhibition of the medial thalamus by the ventral posterior (VP) nucleus of the thalamus, via a circuit that the authors described and named prosencephalomesencephalic modulatory circuit (PMMC). Two pathways are suggested as activators of the PMMC: the neospinothalamic/neotrigeminothalamic and ventral spinothalamic tracts. The interruption of this circuit or of its activators, at any point, would lead to the release of the medial thalamus from the inhibitory influences of VP, allowing the manifestation of the paleopain. It is postulated that the constant burning, tingling element of NPP is nothing more than the clinical expression of the paleopain. Evidence to support this hypothesis is provided. As a direct consequence of the presented hypothesis, the substantia nigra pars reticulata is proposed as a new target of deep brain stimulation for the treatment of the constant burning, tingling element of NPP.

Possible mechanisms involved in subthalamotomy-induced dyskinesia in patients with Parkinson's disease.

BACKGROUND/AIMS: Operation-induced dyskinesia (OID) occurs in approximately 10% of patients submitted to subthalamotomy. The goal of the authors was to determine the possible causes of this feared complication. METHODS: The 54 patients who underwent unilateral subthalamotomy were divided into two groups: the OID group (OIDG), composed of 6 patients who developed dyskinesia following the operation, and the control group (CG), consisting of 48 patients who did not present this complication. The two groups were compared regarding age; sex; presence of levodopa-induced dyskinesia (LID) and/or stimulation-induced dyskinesia (SID); side of the operation; territories of the subthalamic nucleus (STN) involved by the lesion, and degree of lesion extension towards the zona incerta (ZI). RESULTS: The lesion involved the dorsolateral territory of the STN and was almost completely restricted to this nucleus in all patients of the OIDG, while it spread to the ZI in all but 1 patient of the CG. SID was significantly (p < 0.05) more frequent in the OIDG. There was also a strong trend favoring LID (p = 0.055). CONCLUSIONS: Damage to the dorsolateral territory of the STN and sparing of the ZI seem to be essential for the development of OID. SID and, to a lesser extent, LID are apparently significant risk factors for the development of this complication.