Bands of Fontana are caused exclusively by the sinusoidal path of axons in peripheral nerves and predict axon path; evidence from rodent nerves and physical models

The precise cause of the bands of Fontana, striations on peripheral nerves visible to the naked eye, has been the subject of debate for hundreds of years. Some researchers have described them as reflecting the sinuous course of nerve fibres passing through nerves, and others have proposed that endoneurial collagen and sheaths surrounding nerves play a role in their appearance. We hypothesised that the bands are caused exclusively by reflection of light from the surfaces of nerve fibres travelling in phase in sinusoidal waveforms through peripheral nerves. We aligned images of obliquely illuminated nerves with confocal images of axons in those nerves, and the numbers and positions of the bands precisely matched the axonal waves. We also developed three‐dimensional models of nerves with representations of the sinusoidal path of axons at their surface. We observed patterns resembling the bands of Fontana when these models were obliquely illuminated. This provides evidence that the bands of Fontana can be caused by light reflected sinusoidal path of axons alone. We subsequently describe a mechanism of band production based on our observations of both nerves and models. We report that smaller diameter nerves such as phrenic nerves and distal branches of sciatic nerves have shorter band intervals than larger nerves, such as proximal trunks of sciatic nerves, and that shorter band intervals correlate with longer axons per unit length of nerve, which suggests a greater tolerance to stretch. Inspection of banding patterns on peripheral nerves may permit prediction of axon length within nerves, and assist in the interpretation of nerve conduction data, especially in diseases where axon path has become altered.     

Quality of life after hemifacial spasm surgery: French versions of the HFS-8 and HFS-30 questionnaires

ObjectivesThe aim of the present study was to assess quality of life before and after surgery for hemifacial spasm, in order to validate two specific quality of life scales translated in French. Surgical results and complications were reported.Material and methodsTwenty-three patients with hemifacial spasm treated by microvascular decompression were retrospectively included. The HFS-8 and HFS-30 quality of life scales were translated from English into French using a forward-backward method and implemented on patients at least one year after surgery.ResultsMedian HFS-8 and HFS-30 values were respectively 16 ± 12.5 (range: 8–20.5) and 38 ± 38.5 (range: 23–61.5) before surgery and 0.5 ± 4.5 (range: 0–4.5) and 5 ± 17.5 (range: 1–18.5) after surgery, showing significant improvement in quality of life (P < 0.001). The internal consistency of both scales was excellent (Cronbach's alpha > 0.9), and they were significantly correlated (Pearson coefficient = 0.95; 95% CI [0.91; 0.98]; P < 0.0001). Success rates were 83% and 91%, respectively, after primary and revision surgeries. Complications were transient with minor consequences in 80% of cases, but could impact quality of life when lasting.ConclusionsThese results support the validity of the French versions of HFS-8 and HFS-30. Microvascular decompression is a safe and effective treatment for hemifacial spasm, and these scales are reliable tools to assess postoperative quality of life.     

Displasia septoóptica: alteraciones oftalmológicas en una serie de 5 casos

Septo-optic dysplasia (SOD) is a rare congenital condition of unknown cause, with a characteristic triad that includes optic nerve hypoplasia, pituitary function abnormalities and midline brain defects, in addition to a broad spectrum of symptoms and associations.A total of five clinical cases are presented, four of which met the complete classic triad. All of them showed a wide variety of ophthalmological, endocrinological and neurological alterations.Within the ophthalmological spectrum of SOD, papillary hypoplasia and ocular motility alterations (nystagmus, strabismus) stand out. Other less frequent ones may also appear, such as pupillary alterations, microphthalmia and coloboma.Given the suspicion of SOD, brain MRI scan should be performed, as well as consultation with the paediatric department in order to complete the study and indicate, if necessary, systemic treatment.     

氢氧化钙糊剂与根管内感染控制

感染控制对根管治疗的成功至关重要。尽管随着器械及设备的进步，对根管的清理及成形取得了很大的进展；然而，由于根管系统解剖结构错综复杂，使得获取清洁根管面临各种问题。例如：机械预备的宽度有限，不能彻底清理感染牙本质；冲洗技术的运用虽然可以去除根管器械预备后形成的玷污层，但对细菌内毒素的清除还是难以达到理想的效果，而残留的微生物、毒素等若得不到清除可能会在根尖周组织形成持续感染。因此，除外机械预备和冲洗，根管封药也是感染根管治疗过程中的重要步骤。氢氧化钙糊剂以其高效的抗菌作用在临床得到广泛使用。文章将对根管封药的必要性、氢氧化钙的作用机制及临床应用做一介绍。