Neuroendoscopy has become common in the field of pediatric neurosurgery. As an alternative procedure to cerebrospinal fluid shunt, endoscopic third ventriculostomy has been the routine surgical treatment for obstructive hydrocephalus. However, the indication is still debatable in infantile periods. The predictors of late failure and how to manage are still unknown. Recently, the remarkable results of endoscopic choroid plexus coagulation in combination with third ventriculostomy, reported from experiences in Africa, present puzzling complexity. The current data on the role of neuroendoscopic surgery for pediatric hydrocephalus is reported with discussion of its limitations and future perspectives, in this review.
Twenty years have passed since distraction osteogenesis was introduced into the field of craniomaxillofacial surgery, with distraction osteogenesis gradually consolidating its position for midface advancement in syndromic craniosynostosis. On the other hand, no consensus has been reached regarding its adaptation to calvarial bone. We reported that distraction osteogenesis was useful in posterior cranial vault expansion, and subsequently, similar reports have been successively observed worldwide. In posterior cranial vault distraction, intracranial capacity could be greatly expanded due to its simultaneous expansion with the scalp, with little risk of relapse because new bone is regenerated in the distraction gap. The possibility was suggested that the standard of first carrying out fronto-orbital advancement (FOA) for brachycephaly observed in syndromic craniosynostosis will greatly change posterior cranial vault distraction.
A paradigm shift is currently ongoing in the treatment of spasticity in childhood in Japan. Functional posterior rhizotomy (FPR), which was first introduced to Japan in 1996, is best indicated for children with spastic cerebral palsy, regardless of the clinical severity of spasticity. Surgery is generally carried out in the cauda equina, where the posterior root is separated from the anterior one, and neurophysiological procedures are used to judge which nerve root/rootlet should be cut. The outcome of FPR is favorable for reducing spasticity in the long-term follow-up. Intrathecal baclofen (ITB) treatment for childhood spasticity was approved in 2007 in Japan and the number of children undergoing ITB pump implantation has been gradually increasing. ITB treatment is best indicated for children with severe spasticity, especially those with dystonia, regardless of the pathological background. Since it is a surgery performed to implant foreign bodies, special attention should be paid to avoid perioperative complications such as CSF leakage, meningitis, and mechanical failure. Severely disabled children with spasticity would benefit most from ITB treatment. We would especially like to emphasize the importance of a strategic approach to the treatment of childhood spasticity. The first step is to reduce spasticity by FPR, ITB, and botulinum toxin injection. The second step is to aim for functional improvement after controlling spasticity. Traditional orthopedic surgery and neuro-rehabilitation form the second step of treatment. The combination of these treatments that allows them to complement each other is the key to a successful treatment of childhood spasticity.
We are beginning to understand the molecular biology of hydrocephalus and its related diseases. X-linked hydrocephalus (XLH), holoprosencephaly (HPE), Dandy–Walker malformation (DWM), and neural tube defect (NTD) can all be discussed with respect to their available molecular genetics knowledge base and its clinical applications. XLH is single gene disorder caused by mutations in the neural cell adhesion molecule-encoding L1CAM (L1) gene. Our knowledge of the molecular basis of XLH is already being applied clinically in disease diagnosis, disease classification, and prenatal diagnosis. However, the molecular mechanism underlying XLH-related hydrocephalus still needs to be clarified. Sixteen causative genes for HPE have been identified, of which mutations are most often found in SHH, ZIC2, SIX3, and TGIF. Genetic interactions, gene complexity, and the wide variety of HPE phenotypes and genotypes are topics for future study. For DWM, two important loci, 3q24, which includes the FOXC1 gene, and 6q25.3, which includes the ZIC1 and ZIC4 genes, were recently identified as causative areas. The planar cell polarity (PCP) genes CELSR1, CELSR2, VANGL1, and VANGL2 have been implicated in NTD; these genes have roles in neural tube closure and ependymal ciliary movement.
The traditional hypothesis of cerebrospinal fluid (CSF) hydrodynamics presumes that CSF is primarily produced in the choroid plexus (CP), then flows from the ventricles into the subarachnoid spaces, and mainly reabsorbed in the arachnoid granulations. This hypothesis is necessary to reconsider in view of recent research and clinical observations. This literature review presents numerous evidence for a new hypothesis of CSF hydrodynamics—(1) A significantly strong relationship exists between the CSF and interstitial fluid (IF), (2) CSF and IF are mainly produced and absorbed in the parenchymal capillaries of the brain and spinal cord. A considerable amount of CSF and IF are also absorbed by the lymphatic system, and (3) CSF movement is not unidirectional flow. It is only local mixing and diffusion.
Magnetic resonance imaging (MRI) can depict not only anatomical information, but also physiological factors such as velocity and pressure gradient. Measurement of these physiological factors is necessary to understand the cerebrospinal fluid (CSF) environment. In this study we quantified CSF motion in various parts of the CSF space, determined changes in the CSF environment with aging, and compared CSF pressure gradient between patients with idiopathic normal pressure hydrocephalus (iNPH) and healthy elderly volunteers. Fifty-seven healthy volunteers and six iNPH patients underwent four-dimensional (4D) phase-contrast (PC) MRI. CSF motion was observed and the pressure gradient of CSF was quantified in the CSF space. In healthy volunteers, inhomogeneous CSF motion was observed whereby the pressure gradient markedly increased in the center of the skull and gradually decreased in the periphery of the skull. For example, the pressure gradient at the ventral surface of the brainstem was 6.6 times greater than that at the convexity of the cerebrum. The pressure gradient was statistically unchanged with aging. The pressure gradient of patients with iNPH was 3.2 times greater than that of healthy volunteers. The quantitative analysis of 4D-PC MRI data revealed that the pressure gradient of CSF can be used to understand the CSF environment, which is not sufficiently given by subjective impression of the anatomical image.
We reviewed reports about the postoperative course of hemifacial spasm (HFS) after microvascular decompression (MVD), including in our own patients, and investigated treatment for delayed resolution or recurrence of HFS. Symptoms of HFS disappear after surgery in many patients, but spasm persists postoperatively in about 10–40%. Residual spasm also gradually decreases, with rates of 1–13% at 1 year postoperatively. However, because delayed resolution is uncommon after 1 year postoperatively, the following is advised: (1) In patients with residual spasms after 1 year postoperatively (incomplete cure) or who again experience spasm ≥ 1 year postoperatively (recurrence), re-operation is recommended if the spasms are worse than before MVD. (2) When re-operation is considered, preoperative magnetic resonance imaging (MRI) findings and intraoperative videos should be reviewed to ensure that no compression due to a small artery or vein was missed, and to confirm that adhesions with the prosthesis are not causing compression. If any suspicious findings are identified, the cause must be eliminated. Moreover, because of the risk of nerve injury, decompression of the distal portion of the facial nerve should be performed only in patients in whom distal compression is strongly suspected to be the cause of symptoms. (3) Cure rates after re-operation are high, but complications such as hearing impairment and facial weakness have been reported in 10–20% of cases, so surgery must be performed with great care.
Peroneal nerve entrapment neuropathy (PNEN) is one cause of numbness and pain in the lateral lower thigh and instep, and of motor weakness of the extensors of the toes and ankle. We report a less invasive surgical procedure performed under local anesthesia to treat PNEN and our preliminary outcomes. We treated 22 patients (33 legs), 7 men and 15 women, whose average age was 66 years. The mean postoperative follow-up period was 40 months. All patients complained of pain or paresthesia of the lateral aspect of affected lower thigh and instep; all manifested a Tinel-like sign at the entrapment point. As all had undergone unsuccessful conservative treatment, we performed microsurgical decompression under local anesthesia. Of 19 patients who had undergone lumbar spinal surgery (LSS), 9 suffered residual symptoms attributable to PNEN. While complete symptom abatement was obtained in the other 10 they later developed PNEN-induced new symptoms. Motor weakness of the extensors of the toes and ankle [manual muscle testing (MMT) 4/5] was observed preoperatively in 8 patients; it was relieved by microsurgical decompression. Based on self-assessments, all 22 patients were satisfied with the results of surgery. PNEN should be considered as a possible differential diagnosis in patients with L5 neuropathy due to lumbar degenerative disease, and as a causative factor of residual symptoms after LSS. PNEN can be successfully addressed by less-invasive surgery performed under local anesthesia.
Three-dimensional (3D) computer graphics (CG) are useful for preoperative planning of neurosurgical operations. However, application of 3D CG to intraoperative navigation is not widespread because existing commercial operative navigation systems do not show 3D CG in sufficient detail. We have developed a microscopic optically tracking navigation system that uses high-resolution 3D CG. This article presents the technical details of our microscopic optically tracking navigation system. Our navigation system consists of three components: the operative microscope, registration, and the image display system. An optical tracker was attached to the microscope to monitor the position and attitude of the microscope in real time; point-pair registration was used to register the operation room coordinate system, and the image coordinate system; and the image display system showed the 3D CG image in the field-of-view of the microscope. Ten neurosurgeons (seven males, two females; mean age 32.9 years) participated in an experiment to assess the accuracy of this system using a phantom model. Accuracy of our system was compared with the commercial system. The 3D CG provided by the navigation system coincided well with the operative scene under the microscope. Target registration error for our system was 2.9 ± 1.9 mm. Our navigation system provides a clear image of the operation position and the surrounding structures. Systems like this may reduce intraoperative complications.
The Concorde position was developed to approach pineal and cerebellar lesions with a midline suboccipital craniotomy. The neutral head position is needed to divide the occipital muscles symmetrically. The patient’s head is tilted to the right and the face is turned to the right for the microscopic procedure to keep the midline of the patient’s head axis straight in the surgical field for comfortable and accurate surgical manipulation. However, intraoperative repositioning of the patient’s head is somewhat difficult to release the holding arm of the Sugita head holder in the original method. We found that a skew head rotation by fixing the head asymmetrically in the Sugita head holder is very quick and convenient to obtain the optimal head position both for a craniotomy and a microscopic procedure.
Confirming the patency of the proximal parent and distal artery is necessary in cerebral aneurysm surgery. To understand the relationship between the parent and distal arteries of the aneurysm, the blood vessels running through the subarachnoid space should be extensively dissected, which is time consuming. To examine the efficacy of a temporary clip with indocyanine green (ICG) technique, in which the parent artery is temporarily occluded using a temporary clip, an ICG videoangiography (ICGVAG) is performed to clarify the relationship between the distal artery and the proximal parent artery. Three patients with a distal aneurysm. This technique was used to confirm the connection of the parent and the distal artery in distal aneurysms. With regard to middle cerebral artery (MCA), the procedure is conducted as follows. First, the M2 within the Sylvian fissure is investigated to ensure the absence of atherosclerosis and perforators and that this vessel could undergo occlusion by temporary clipping. The subarachnoid space surrounding the distal artery of the lesion site suspected of an existent aneurysm is dissected. The image range of the ICGVAG is set sufficiently wide to accommodate the possibility that the distal artery is not the artery that was anticipated. Subsequently, after the temporary clip occlusion is completed, the ICGVAG is recorded. In the three distal aneurysms, the relationship between the aneurysm, the distal artery, and the parent artery was confirmed. This method was useful, suggesting that unnecessary dissection in the subarachnoid space might be reduced.
As cerebrovascular anastomosis is performed in moist conditions that may impede precise manipulations, surgeons must undergo extensive preoperative training. We developed a simple moist-condition training method. It involves placing a free-floating inner platform hosting an artery from a chicken wing in an outer container filled with tap water to just below the specimen. Trainees performed anastomosis under magnification. Training sessions mimicked difficulties encountered during operations such as poor visibility of the lumen and problems handling the sutures. A retrospective comparison of 100 wet- and 100 dry-condition training sessions for end-to-side anastomoses with 8 stitches showed that under moist condition the time required for the entire procedure was significantly longer (17.8 ± 2.1 vs. 15.3 ± 2.1 min, p < 0.01) and the incidence of wrong stitching was greater (0.38 vs. 0%, p = 0.04). In 8 cases after introducing moist-condition training, the time required in superficial temporal artery to middle cerebral artery bypass surgery was significantly shorter than 8 cases before introducing the training (32.3 ± 5.6 min vs. 48.3 ± 15.9 min, p = 0.01). Incidence of wrong stitches was less in cases after introducing moist-condition training (2.7 vs. 7.4%, p = 0.10). Those indicate that moist-condition training is a useful and practical step and a bridge between training for basic manipulations under dry conditions and actual surgery.