Update on Mechanism and Therapeutic Implications of Spinal Cord Stimulation and Cerebral Hemodynamics: A Narrative Review.

Spinal cord stimulation (SCS) is well known for its early role in the management of chronic pain, mainly failed back surgery syndrome (FBSS), spasticity, and bowel and bladder dysfunction. In more recent years, SCS has been proposed for patients suffering from refractory angina or peripheral vasculopathies in order to gain symptom relief, thus indicating some hemodynamic effect on the peripheral circulation. Taking into account this scientific observation, since the late1980s, researchers have started to investigate the potential effect of SCS on cerebral blood flow (CBF) regulation and its possible application in certain pathological settings dealing with vascular pattern dysfunction, such as ischemia, subarachnoid hemorrhage, head trauma, and brain tumors. The aim of this study was to review the scientific literature about SCS and its effect on CBF, evaluating the results both in "physiological" experimental models and clinical studies, as well as in the particular pathological conditions we have mentioned above.

Distribution of Cerebrovascular Phenotypes According to Variants of the ENG and ACVRL1 Genes in Subjects with Hereditary Hemorrhagic Telangiectasia.

Hereditary Hemorrhagic Telangiectasia (HHT) is an autosomal dominant disorder caused, in more than 80% of cases, by mutations of either the endoglin (ENG) or the activin A receptor-like type 1 (ACVRL1) gene. Several hundred variants have been identified in these HHT-causing genes, including deletions, missense and nonsense mutations, splice defects, duplications, and insertions. In this study, we have analyzed retrospectively collected images of magnetic resonance angiographies (MRA) of the brain of HHT patients, followed at the HHT Center of our University Hospital, and looked for the distribution of cerebrovascular phenotypes according to specific gene variants. We found that cerebrovascular malformations were heterogeneous among HHT patients, with phenotypes that ranged from classical arteriovenous malformations (AVM) to intracranial aneurysms (IA), developmental venous anomalies (DVA), and cavernous angiomas (CA). There was also wide heterogeneity among the variants of the ENG and ACVRL1 genes, which included known pathogenic variants, variants of unknown significance, variants pending classification, and variants which had not been previously reported. The percentage of patients with cerebrovascular malformations was significantly higher among subjects with ENG variants than ACVRL1 variants (25.0% vs. 13.1%, p < 0.05). The prevalence of neurovascular anomalies was different among subjects with different gene variants, with an incidence that ranged from 3.3% among subjects with the c.1231C > T, c.200G > A, or c.1120C > T missense mutations of the ACVRL1 gene, to 75.0% among subjects with the c.1435C > T missense mutation of the ACVRL1 gene. Further studies and larger sample sizes are required to confirm these findings.

History of Chiari type I malformation.

Chiari type I malformation (CIM) was first described in the late 19th Century. However, it still raises a great interest among the scientific Community because of the increasing number of diagnosed cases, the still unclear pathogenesis and natural history and the different options in the surgical management. The present review aims at analyzing the centenary history of CIM, starting from the first description done by Hans Chiari to the more recent classification, in order to introduce such a complex disease and to show the way followed for its assessment over the time.

Section of the filum terminale: is it worthwhile in Chiari type I malformation?

A section of the filum terminale (SFT) is used for the surgical treatment of isolated tethered cord or that resulting from neurulation disorders. More recently, it has been proposed for the management of the occult tethered cord syndrome (OTCS), though it is still under debate. Even more controversial appears to be the use of SFT in patients with Chiari type I malformation (CIM), which is based on the possible presence of OTCS. This review shows that: (1) there are issues both in favor and against the occurrence of OTCS, (2) there is no significant correlation between CIM and tethered cord, the old "caudal traction theory" being not supported by clinical or experimental evidences. On these grounds, a relationship between CIM and OTCS is hard to be demonstrated, (3) a subgroup of patients with CIM suffering from OTCS may exist and benefit from SFT.

What Is the Best Timing of Repeated CT Scan in Mild Head Trauma with an Initially Positive CT Scan?

BACKGROUND: Mild traumatic brain injury (MTBI) is among the most common causes of emergency admission. Current guidelines have clearly evidenced risk factors and neurologic signs that should suggest computed tomography (CT) of the head at admission and indications for the first repeated CT scan. However, the role and frequency of further repeated CT scans after an initially positive scan are still unclear. METHODS: We retrospectively analyzed 222 patients admitted in our hospital for clinical observation after an MTBI and a positive initial scan. Repeated CT scans were categorized according to timing from the first scan. All the scans were evaluated for the presence of posttraumatic lesions. We classified the data in 3 groups according to the timing of CT scans: A (CT scans at t0-t12-t24), B (t0-t12-t48), and C (t0-t24-t48). Differences in worsening or stability of posttraumatic lesions were compared by the χ2 test. RESULTS: 146 CT scans were performed at t12, 81 at t24, and 143 at t48. The initial CT scan was positive for epidural hematoma in 17 cases, subdural hematoma in 106, subdural hygroma in 10, intracerebral contusion in 110, subarachnoid hemorrhage in 109, and intraventricular hemorrhage in 12. None of the posttraumatic lesions showed significant worsening or at the first or second CT scan in any of the 3 groups. CONCLUSIONS: The treatment of patients in clinically stable condition with an MTBI and posttraumatic intracranial lesions at initial CT scan has been shown to minimally benefit from repeated CT scans. Given neurologic stability, a control scan can be safely delayed up to 48 hours to avoid unnecessary scans.

Postoperative Epileptic Seizures in Children: Is the Brain Incision a Risk Factor?

BACKGROUND: Postoperative seizures (PSs) after neurosurgical operations are common but little is known about the role of surgical brain incision on their genesis. This topic has not been addressed so far. OBJECTIVE: To verify if the corticotomy affects the risk of PSs and postoperative epilepsy (PE) in children. METHODS: One hundred forty-three consecutive pediatric cases operated on for supratentorial lesions at the same institution in the last 15 yr have been retrospectively reviewed by dividing them into group A, 68 children who required brain corticotomy mainly for hemispheric tumors, and group B, 75 children treated through extracortical approaches mainly for suprasellar and optic tumors. Patients with possible "epileptic" biases, like preoperative seizures, were excluded. RESULTS: No significant differences have been found between group A and B as far as incidence of PSs (11.7% vs 14.5%) and PE (4.5% vs 6.5%), timing, and type of seizures are concerned after a mean 6.8 yr follow-up. The size of corticotomy in group A (<3 cm2 vs >3 cm2) had no impact on epileptogenesis as well as the other variables considered in both groups (age, sex, extent of lesion resection). CONCLUSION: This study shows that the surgical cortical "trauma" would not represent a risk factor for PSs and PE. According to the present analysis and the literature, other causes seem to be involved (namely, electrolytic imbalance and brain gliosis). This information is important for preoperative surgical planning and postoperative management. A validation by both adult series and prospective studies is needed.

Electrocardiographic-Guided Technique for Placement of Ventriculoatrial Shunts: A Valid and Cost-Effective Technical Simplification.

BACKGROUND: Ventriculoatrial (VA) shunt is a routine technique for the treatment of hydrocephalus. The correct position at the superior vena cava-right atrium junction is generally assessed by radiography. We present the first experience of an alternative, nonradiographic technique to assess the distal end of the VA shunts through an electrocardiographic (EKG) method. The technique has developed from the large experience of central venous catheters (CVC) worldwide; the EKG-guided method is a common and validated alternative to standard radiologic control of the location of the tip of any CVC. METHODS: Five consecutive patients underwent VA shunt with venous catheter positioned with the EKG-guided technique. The position of the catheter tip was verified by standard chest radiography. RESULTS: Four men and 1 woman (mean age, 45.4 years) underwent VA shunt for hydrocephalus with the EKG-guided technique. The side of internal jugular vein puncture was the right side in 4 cases and the left side in 1 case. As confirmed by radiography, all VA shunt tips were located within the correct range. There was no radiologic evidence of procedure-related complication or catheters that had to be replaced. CONCLUSIONS: The EKG-guided technique for VA shunts is as accurate as fluoroscopy, but simpler, more readily available, less expensive, safer, and more cost effective. It reduces the need of radiography and radiologic exposition for both patients and operators. The EKG method may be a valid and cost-effective alternative to standard radiologic control in VA shunts, as for any central venous access device, and could become the preferential method for confirming tip position during VA shunt surgery.