Vagal nerve stimulation cycles alter EEG connectivity in drug-resistant epileptic patients: A study with graph theory metrics.

OBJECTIVE: Vagal Nerve Stimulation (VNS) is an effective treatment for Drug-Resistant (DR) epilepsy. Albeit the corroborated effectiveness of VNS, little is known about how VNS works. We aim to leverage quantitative Electroencephalography (qEEG) to study how the brain responds to VNS cycles. METHODS: Eighteen subjects with DR epilepsy were enrolled in our study. 64-channel EEG was recorded during VNS stimulation. Periods of stimulation (VNS), preceding (preVNS) and following stimulation (postVNS) were identified via an electrode placed on the stimulator. We used qEEG analysis to assess changes in spectral and network activity that characterize these conditions. Graph theory metrics were used to calculate differences in network connectivity. RESULTS: No differences were found in spectral activity between preVNS, VNS, and postVNS. Graph theory showed consistent changes in network organization expressed by Small World Index (SWI), Betweenness Centrality (BtwC), and Global Efficiency (gE). These changes were most significant in the slow EEG bands. CONCLUSIONS: In DR epilepsy, VNS has a significant effect on brain network activity, as assessed by EEG connectivity, acting on widespread network distribution rather than band-power. SIGNIFICANCE: Our findings support the hypothesis that VNS acts on epilepsy by influencing diffuse network connectivity in the brain.

End-to-side nerve neurorrhaphy: critical appraisal of experimental and clinical data.

End-to-side neurorrhaphy (ESN) or terminolateral neurorraphy consists of connecting the distal stump of a transected nerve, named the recipient nerve, to the side of an intact adjacent nerve, named the donor nerve, "in which only an epineurial window is performed". This procedure was reintroduced in 1994 by Viterbo, who presented a report on an experimental study in rats. Several experimental and clinical studies followed this report with various and sometimes conflicting results. In this paper we present a review of the pertinent literature. Our personal experience using a sort of end-to-side nerve anastomosis, in which the donor nerve is partially transected, is also presented and compared with ESN as defined above. When the proximal nerve stump of a transected nerve is not available, ESN, which is claimed to permit anatomic and functional preservation of the donor nerve, seems an attractive technique, though yet not proven to be effective. Deliberate axotomy of the donor nerve yields results that are proportional to the entity of axotomy, but such technique, though resembling ESN, is an end-to-end neurorrhaphy. Neither experimental or clinical evidence support liberalizing the clinical use of ESN, a procedure with only an epineurial window in the donor nerve and without deliberate axotomy. Much more experimental investigation needs to be done to explain the ability of normal, intact nerves to sprout laterally. Such procedure appears justified only in an investigational setting.

[Pediatric craniopharyngioma: long-term results in 61 cases]. / Craniofaringioma pediatrico: risultati a lungo termine in 61 casi.

AIM: The aim of this study was to analyze the long-term results of the surgical management of craniopharyngioma in children by reviewing a series of patients consecutively treated in a single institution, and to assess the efficacy of intratumoral chemotherapy with interferon-alpha. METHODS: Sixty-one paediatric patients (38 males and 23 females; mean age: 8 years) have been surgically treated in the last 20 years. The goal of surgery was to remove the tumour as much as possible. Postoperative radiotherapy was administered only to children aged more than 4 year old and with postsurgical evolutive remnant. Three patients were treated with intratumoral administration of interferon-alpha. The mean follow-up is 8.4 years (median: 7 years). RESULTS: All the 55 surviving patients enjoy a normal social life, except for 3 of them (visual and/or neurological deficits); endocrine function, compromised in 3/5 of cases, is managed by chronic hormone replacement; neuropsychological assessment is satisfactory in almost all the cases. Although obesity does not seem to be an important social limit, it represents a real management problem. Interferon-a was useful in transitorily arresting the growing cystic craniopharyngiomas. CONCLUSION: The current experience confirms the still remarkable challenges in the treatment of craniopharyngioma in childhood. Surgery should aim not only at removing the tumour, but also at preserving the late neuro-endocrinological functions. Intracystic chemotherapy with interferon-alpha might represent an effective option to postpone the surgical operation until the maturation of the hypothalamic-hypophyseal pathway is completed. However, it can not replace the traditional surgical management.