Foramen magnum meningioma: The midline suboccipital subtonsillar approach.

OBJECTIVES: Foramen magnum meningiomas (FMMs) represent a technical challenge even for experienced neurosurgeons, because they grow in close contact with osteoarticular, nervous, and vascular structures that cannot be sacrificed or retracted during surgery. Our goal is to present our experience with 24 cases of surgically resected foramen magnum meningiomas used the midline suboccipital subtonsillar approach and discussed the present risks associated with the treatment of this condition. PATIENTS AND METHODS: We retrospectively reviewed all patients who underwent surgery treatment for foramen magnum meningiomas operated on between August 2005 and July 2013. A total of 24 cases were included. Data regarding age, sex, symptoms and sign types, locations, surgical aspects, postoperative new deficits, and follow-up are presented. RESULTS: There were 18 female and 6 male patients (mean age: 52 years). The symptom among most patients (14 patients) was cervico-occipital pain, dysphagia and gait unsteadiness in five, and paresthesia of the upper limbs in four. Total removal of the tumor was achieved in 20 patients, subtotal in two, and partial resection in four patients. Two patients had permanent deficits. Follow-up was 45.6 months (range, 6 months to 8 years), there was no recurrence among tumors totally removed but 1 patient of regrowth among the cases with subtotal removal. CONCLUSIONS: Our experience confirmed that the midline suboccipital subtonsillar approach was accurate in safely removing anterior, anterolateral, and posterior FMMs. There was no significant postoperative complication in the remainder of the patientes, and their conditions improved after surgery.

Increased coherence among striatal regions in the theta range during attentive wakefulness

The striatum, the largest component of the basal ganglia, is usually subdivided into associative, motor and limbic components. However, the electrophysiological interactions between these three subsystems during behavior remain largely unknown. We hypothesized that the striatum might be particularly active during exploratory behavior, which is presumably associated with increased attention. We investigated the modulation of local field potentials (LFPs) in the striatum during attentive wakefulness in freely moving rats. To this end, we implanted microelectrodes into different parts of the striatum of Wistar rats, as well as into the motor, associative and limbic cortices. We then used electromyograms to identify motor activity and analyzed the instantaneous frequency, power spectra and partial directed coherence during exploratory behavior. We observed fine modulation in the theta frequency range of striatal LFPs in 92.5 ± 2.5% of all epochs of exploratory behavior. Concomitantly, the theta power spectrum increased in all striatal channels (P < 0.001), and coherence analysis revealed strong connectivity (coefficients >0.7) between the primary motor cortex and the rostral part of the caudatoputamen nucleus, as well as among all striatal channels (P < 0.001). Conclusively, we observed a pattern of strong theta band activation in the entire striatum during attentive wakefulness, as well as a strong coherence between the motor cortex and the entire striatum. We suggest that this activation reflects the integration of motor, cognitive and limbic systems during attentive wakefulness.

Increased coherence among striatal regions in the theta range during attentive wakefulness.

The striatum, the largest component of the basal ganglia, is usually subdivided into associative, motor and limbic components. However, the electrophysiological interactions between these three subsystems during behavior remain largely unknown. We hypothesized that the striatum might be particularly active during exploratory behavior, which is presumably associated with increased attention. We investigated the modulation of local field potentials (LFPs) in the striatum during attentive wakefulness in freely moving rats. To this end, we implanted microelectrodes into different parts of the striatum of Wistar rats, as well as into the motor, associative and limbic cortices. We then used electromyograms to identify motor activity and analyzed the instantaneous frequency, power spectra and partial directed coherence during exploratory behavior. We observed fine modulation in the theta frequency range of striatal LFPs in 92.5 ± 2.5% of all epochs of exploratory behavior. Concomitantly, the theta power spectrum increased in all striatal channels (P < 0.001), and coherence analysis revealed strong connectivity (coefficients >0.7) between the primary motor cortex and the rostral part of the caudatoputamen nucleus, as well as among all striatal channels (P < 0.001). Conclusively, we observed a pattern of strong theta band activation in the entire striatum during attentive wakefulness, as well as a strong coherence between the motor cortex and the entire striatum. We suggest that this activation reflects the integration of motor, cognitive and limbic systems during attentive wakefulness.

Delayed functional maturation of human neuronal progenitor cells in vitro.

INTRODUCTION: Differentiation of neuronal progenitor cells (NPCs) in vitro into functional neurons is dependent on a complex cascade of molecular signaling pathways, many of which remain unknown. More specifically, in human NPCs the relationship between the expression of typical neuronal marker proteins and functional properties, such as firing action potential and synaptic transmission, is not well understood. In the present report, the immunocytochemical, morphological and electrophysiological changes that human NPCs undergo during neuronal differentiation in vitro were investigated. METHODS: Human NPCs were differentiated toward a neuronal phenotype. The time course of the expression of neuronal markers and morphological cell changes was mapped and passive and active electrophysiological membrane properties assessed, throughout the neuronal maturation process. RESULTS: The acquisition of neuronal markers preceded functional physiological maturation by several weeks. Cell input resistance decreased in the first 2 weeks as cells became less sensitive to input current, while cell capacitance progressively increased with continued neuronal process growth. Functional maturation was observed only by the fifth/sixth week, preceded by a marked increase in Na+ and K+ currents. In contrast, electrophysiological maturation of rodent precursor cells was observed at the end of the first week in vitro. Functionally, human neuronal cells became capable of firing action potentials and forming active synaptic contacts. Many features of the firing pattern however remained immature. CONCLUSIONS: The results showed that human NPCs develop remarkably slowly and retain immature neuronal features for a prolonged period. The importance of Na-dependent activity for proper neuronal maturation is emphasized.

Mesenchymal stem cells maintain TGF-beta-mediated chondrogenic phenotype in alginate bead culture.

This article addresses the stability of chondrogenic phenotype and the transdifferentiation potential of bone marrow-derived mesenchymal stem cells (MSCs) at distinct stages of differentiation. Differentiated MSCs were expected to maintain cartilage-like gene expression pattern in the absence of any chondrogenic growth factor or in the presence of osteogenic signals. MSCs encapsulated in alginate beads were treated with transforming growth factor (TGF)-beta 3 for 3, 6, or 14 days and then cultured in absence of TGF-beta for the remainder of the 2-week culture period. Additionally, cells were cultured in osteogenic medium after TGF-beta-mediated chondroinduction. Gene expression of col2a1, aggrecan, COMP, alkaline phosphatase (AP), and correlating protein synthesis was analyzed. After short-term stimulation with TGF-beta, MSCs maintained a chondrogenic phenotype. Chondrogenic gene expression and protein synthesis directly correlated with the extent of stimulation time and the concentration of TGF-beta. Pretreatment with TGF-beta could prevent AP mRNA expression of encapsulated MSCs. TGF- beta stimulation within the first 3 days of culture seems to be crucial for the expression of a chondrogenic phenotype. Fully differentiated and encapsulated MSCs are not able to transdifferentiate into osteoblasts. These findings give rise to a better understanding of the behavior of cartilage grafts affected by local factors of osteochondral transplantation sites in vivo.

Interstitial irradiation for CNS lesions.

In this study, we investigated the efficacy of brachytherapy in the treatment of 138 patients with intracranial neoplasms of the CNS. Of the total number of patients, 50 presented with glioblastoma multiforme, 45 presented with low-grade glioma, 19 presented with anaplastic astrocytoma, 23 presented with metastases and 1 presented with meningioma. During the execution of this study, seeds of 125I (10-20 mCi) were inserted into the lesions to aim the irradiation at a low dose of 60 Gy in the margin of benign lesions or 1 cm beyond the radiological border of malignant lesions, which were visualized on CT scan. The results of this procedure were evaluated in terms of the survival rates, which were assessed by Kaplan-Meier curves. Significant relationships were not observed between the volume and location of the lesions, the whole-brain radiotherapy and chemotherapy, and the survival time of the patients. A low Karnofsky Index score and older age were associated with a short survival time. In light of the above, it was concluded that interstitial irradiation is a safe and effective method of treatment for brain tumors.

Bulbar trigeminal stereotactic nucleotractotomy for treatment of facial pain.

Many pharmacological and surgical treatments are available for the treatment of chronic facial pain. However, many of them are expensive and often very ineffective. Past publications suggested that bulbar trigeminal stereotactic nucleotractotomy is a very useful procedure for the treatment of neuropathic or oncologic facial pain. The authors describe the results of treatment with stereotactic nucleotractotomy in 58 patients with chronic facial pain. The intensity of the pain was evaluated according to the visual analogue scale, and daily life activities were also evaluated. The conclusion was that this procedure is a safe and effective method for treatment of postherpetic neuralgia, Wallenberg's syndrome and oncologic facial pain but not of trigeminal neuralgia.

Chronic pain after spinal cord injury: clinical characteristics.

The clinical characteristics of chronic pain in spinal cord injury patients are controversial. The authors prospectively evaluated 81 patients with chronic pain due to spinal cord lesions. The mean pain intensity according to the visual analogue scale was 9.4. The most common description of pain was a sensation of burning. The initial pain was more severe in patients presenting with myelopathy due to gunshot injuries (p < 0.001). The pain intensity was not associated with the magnitude of the spinal lesion, location of the lesion, occurrence of myofascial pain syndrome or onset of pain. Pain after spinal cord injury was severe, males were more frequently affected and it was more intense when it was the result of gunshot injury. In about 38% of the patients, pharmacological and rehabilitative procedures were effective. Dorsal root entry zone lesion was effective for the treatment of transitional pain in patients with complete section of the spinal cord, spinal cord stimulation was effective for patients with partial lesions of the spinal cord and intrathecal opioid infusion was effective for both conditions.

Epidural analgesia in labour for a patient with hereditary neuropathy with liability to pressure palsy.

Hereditary neuropathy with liability to pressure palsy (HNPP) is a rare but probably under-diagnosed disorder of peripheral nerves in which individuals suffer from repeated motor and sensory neuropathies (pressure palsies) following brief nerve compression or mild trauma. A seemingly trivial insult such as sitting or kneeling may result in a focal neurological deficit lasting for hours to months. Despite the growing recognition of this problem, information regarding the anaesthetic management of labour is sparse. We present a woman with HNPP who was provided with a modified epidural regimen (low concentration bupivacaine and fentanyl) for analgesia in labour and delivery. Labour progressed uneventfully and there were no neurological sequelae following delivery.

MR and CT imaging in the Dyke-Davidoff-Masson syndrome. Report of three cases and contribution to pathogenesis and differential diagnosis.

Cerebral hemiatrophy or Dyke-Davidoff-Masson syndrome is a condition characterized by seizures, facial asymmetry, contralateral hemiplegia or hemiparesis, and mental retardation. These findings are due to cerebral injury that may occur early in life or in utero. The radiological features are unilateral loss of cerebral volume and associated compensatory bone alterations in the calvarium, like thickening, hyperpneumatization of the paranasal sinuses and mastoid cells and elevation of the petrous ridge. The authors describe three cases. Classical findings of the syndrome are present in variable degrees according to the extent of the brain injury. Pathogenesis is commented.