Cranial Opening Research Articles

An Osteologic Study of Cranial Opening of Optic Canal in Gujarat Region

Optic canal is a bony canal situated in between the roots of lesser wings of sphenoid, lateral to body of sphenoid. It transmits optic nerve and ophthalmic artery, surrounded by meninges. Various authors have studied variations in skull foramina and correlated clinically, as variants in the body structures have been found to be associated with many inherited or acquired diseases. The present study aimed to examine morphologic and morphometric variations in cranial openings of optic canals. The study was undertaken in total 150 dry adult human skulls. The variations in size, shape, presence or absence and duplication or multiplication if any, in optic canal were observed bilaterally. Unusual features such as recess, fissure and notch were also observed bilaterally. Student's t-test was applied to compare size of cranial openings of optic canal on both sides. Similarly, morphologic features related with the canal were studied by calculating frequency and proportions of various parameters. Optic canal was present in all 150 skulls studied bilaterally. The mean maximum dimension of the canal at cranial opening was 5.03±0.72 mm on right side and 5.02±0.76 mm on left side. The shape of the canal was ovoid at cranial opening in all the skulls studied. Duplication of optic canal was present in one skull on left side. Recess was found in 105(35%) sides of total skulls observed. Fissure was found in 20(6.67%) sides and notch was observed in 30(10%) sides of total skulls. The optic canal showed variability in various parameters. Knowledge regarding variations in size, shape and unusual features on cranial opening of optic canal can be helpful to clinicians while approaching optic canal for various invasive procedures such as optic nerve decompression.

No association between seniority of surgeon and postoperative recurrence of chronic subdural haematoma.

Neurosurgical trainees should achieve competency in chronic subdural haematoma (CSDH) drainage at an early stage in training. The effect of surgeon seniority on recurrence following surgical drainage of CSDH was examined. All CSDH cases performed at St George's Hospital in London between March 2009 and March 2012 were analysed. Recurrence was defined as clinical deterioration with computed tomography evidence of CSDH requiring reoperation within six months. The following risk factors were considered: seniority of primary and supervising surgeons, timing of surgery (working hours, outside working hours), patient related factors (age, antiplatelets, warfarin) and operative factors (general vs local anaesthesia, burr holes vs craniotomy, drain use). For recurrent cases, we examined the distance of the cranial opening from the thickest part of the CSDH. A total of 239 patients (median age: 79 years, range: 33-98 years) had 275 CSDH drainage operations. The overall recurrence rate was 13.1%. The median time between the initial procedure and reoperation was 16 days (range: 1-161 days). The only statistically significant risk factor for recurrence was antiplatelets (odds ratio: 2.62, 95% confidence interval: 1.13-6.10, p<0.05). Warfarin, grade of surgeon, timing of surgery, type of anaesthesia, type of operation and use of drains were not significant risk factors. In 26% of recurrent CSDH cases, the burr holes or craniotomy flaps were placed with borderline accuracy. CSDH drainage is a suitable case for neurosurgical trainees to perform without increasing the chance of recurrence.

Clinical anatomy of the orbitomeningeal foramina: variational anatomy of the canals connecting the orbit with the cranial cavity.

In addition to the optic canal and the superior orbital fissure, orbits are connected with the cranial cavity via inconstant canals including the orbitomeningeal foramen. This study has been carried out in order to define many anatomical and radiological details of the orbitomeningeal foramen that are relevant in the clinical practice. Almost 1000 skulls and 50 computerized tomographies were examined to determine incidence, number, length, and caliber of the orbitomeningeal foramen as well as the topography of their orbital and cranial openings. A retrospective study of angiographies carried out on more than 100 children was performed to look for arteries candidate to run through the orbitomeningeal foramen. Orbitomeningeal foramina were detected in 59.46% of skulls and in 54% of individuals by computerized tomography. Orbits with two to five foramina were found. Canals were classified as M-subtype or A-subtype depending on their cranial opening. Large foramina, with the caliber ranging between 1 and 3 mm, were found in 12.17% of orbitomeningeal foramen-bearing orbits. By computed tomography the average caliber measured 1.2 ± 0.3 and 1.5 ± 0.5 mm (p < 0.005) at the orbital and cranial openings, respectively (p < 0.005). Angiographies showed meningo-lacrimal and meningo-ophthalmic arteries, meningeal branches of the lacrimal and supraorbital arteries, and some unidentified arteries that could pass through the orbitomeningeal foramina. Orbitomeningeal foramina are a common occurrence. When large they may house important arteries that can be the source of severe bleedings during deep dissection of the lateral wall of the orbit. Orbital surgeons should be aware of their existence.

Morphometric characteristics of caudal cranial nerves at petroclival region in fetuses.

Morphometric measurements of cranial nerves in posterior cranial fossa of fetus cadavers were carried out in an attempt to identify any asymmetry in their openings into the cranium. Twenty-two fetus cadavers (8 females, 14 males) with gestational age ranging between 22 and 38weeks (mean 30weeks) were included in this study. The calvaria were removed, the brains were lifted, and the cranial nerves were identified. The distance of each cranial nerve opening to midline and the distances between different cranial nerve openings were measured on the left and right side and compared. The mean clivus length and width were 21.2±4.4 and 13.2±1.5mm, respectively. The distance of the twelfth cranial nerve opening from midline was shorter on the right side when compared with the left side (6.6±1.1 versus 7.1±0.8mm, p=0.038). Openings of other cranial nerves did not show such asymmetry with regard to their distance from midline, and the distances between different cranial nerves were similar on the left and right side. Cranial nerves at petroclival region seem to show minimal asymmetry in fetuses.

A morphometric evaluation of the optic canal: Comparative study between computerized tomographic study and direct anatomic study

Objective: The objective of this study is to probe into the normal anatomy of the optic canal by comparison of dry skull and computed tomography (CT) images of live subjects. Materials and Methods: The optic canals of 107 normal subjects were examined by thin layer CT scan images in axial and coronal sections. 25 dry skulls were examined by using sliding Vernier caliper. The width, height of optic canal in both opening (cranial and orbital side) were measured. The medial, lateral walls (LWs) of optic canal were also measured. By using mathematical formula, the area of optic canal was calculated. Student's t-test was applied to compare the results statistically. Results: The height of optic canal at orbital and cranial opening in both CT and direct study was 4.12 ± 0.63 mm, 3.6 ± 0.76 mm and 5.7 ± 0.76 mm, 5.17 ± 0.81 mm, respectively. The width at orbital and cranial opening in both CT and direct was 2.98 ± 0.56 mm, 4.59 ± 0.83 mm and 4.74 ± 0.47 mm, 5.48 ± 0.76 mm, respectively. The length of medial and LW in both CT and direct study was 10.63 ± 1.72 mm, 9.2 ± 1.33 mm and 9.1 ± 1.46 mm, 8.66 ± 1.31 mm, respectively. The area was 1.43 cm΂ in direct study and in CT study it was 1.19 cm΂. Conclusion: Given parameters may be helpful for surgeons to plan the proper way to approach the optic canal.

Aberrant carotid artery in the middle ear.

Carotid artery abnormality in the middle ear is a rare clinical condition. Recognition of the problems related with this abnormality is important since it may mimic vascular tumors. Any intervention with incomplete evaluation can be fatal. A 23-year-old girl with carotid abnormality and sensorineural hearing loss, unsteadiness and tinnitus is presented. She was followed for 2 months elsewhere assuming that she had Meniere's disease and had previously received some medication for otitis media with effusion. Tomography and magnetic resonance imaging of the temporal bone are very helpful for visualization of an aberrant carotid in the middle ear. Radiological presentations are the reduced caliber of the aberrant carotid, an absence of cranial opening of carotid canal, tubular coursing along the medial wall of the middle ear in continuity with the horizontal carotid canal, dehiscence of the lateral carotid plate and enlargement of the tympanic canalicus.

Small size craniotomy in endoscopic procedures: Technique and advantages.

Background:Endoscopic procedure has been known as the method of choice for treatment of hydrocephalus with 8.5% complication rate. It seems that good dural closure, reconstructing bone defect and perfect pericranium suturing can decrease the wound complications. Here, we describe the method of minicraniotomy instead of the burr hole in the endoscopic procedure.Materials and Methods:A case–control study regarding the cranial opening for endoscopic surgery was done in 45 patients of <12 months age; 15 patients in case group for minicraniotomy and 30 infants as control group for burr hole. They were followed at least 1-month for complications including cerebrospinal fluid collection, wound dehiscence, wound infection, and meningitis.Result:Patients were between 1 and 11 months. Hydrocephalus (73%) was the most common etiology for endoscopic surgery in this series, followed by the arachnoid cyst (20%). Two patients in the case group and eight in control group developed complications. Meningitis was found in one infant in the control group. Despite less complications in the case group the difference between two cohorts was not statistically significant.Conclusion:Minicraniotomy with providing more space in comparison to burr hole makes dural closure possible. It provides a small bone flap that can be replaced inside the bone defect. In spite of nonsignificant statistical difference between two groups regarding complication rate, we found less wound complications with minicraniotomy. Therefore, we advise this technique for the endoscopic procedure and propose minicraniotomy even in the older population to provide better dural opening, watertight dural closure and reconstructing the bone defect.

CT false-profile view of the hip: a reproducible method of measuring anterior acetabular coverage using volume CT data.

To devise a simple, reproducible method of using CT data to measure anterior acetabular coverage that results in values analogous to metrics derived from false-profile radiographs. Volume CT images were used to generate simulated false-profile radiographs and cross-sectional false-profile views by angling a multiplanar reformat 115° through the affected acetabulum relative to a line tangential to the posterior margin of the ischial tuberosities. The anterolateral margin of the acetabulum was localized on the CT false-profile view corresponding with the cranial opening of the acetabular roof. Anterior center edge angle (CEA) was measured between a vertical line passing through the center of the femoral head and a line connecting the center of the femoral head with the anterior edge of the condensed line of the acetabulum (sourcil). Anterior CEA values measured on CT false-profile views of 38 symptomatic hips were compared with values obtained on simulated and projection false-profile radiographs. The CT false-profile view produces a cross-sectional image in the same obliquity as false-profile radiographs. Anterior CEA measured on CT false-profile views were statistically similar to values obtained with false-profile radiographs. CT technologists quickly mastered the technique of generating this view. Inter-rater reliability indicated this method to be highly reproducible. The CT false-profile view is simple to generate and anterior CEA measurements derived from it are similar to those obtained using well-positioned false-profile radiographs. Utilization of CT to assess hip geometry enables precise control of pelvic inclination, eliminates projectional errors, and minimizes limitations of image quality inherent to radiography.

Anatomic study and clinical significance of extended endonasal anterior skull base surgery.

This study is to investigate the anatomical relationship of endonasal approach for anterior skull base surgery, and to determine the boundaries between anterior basicranial craniotomy and the security of operative techniques. A total of 10 adult dry skulls and 13 adult cadaveric heads processed by formalin were examined under operating microscope. The micro-anatomic structures of the turbinate, sphenoid sinus, ethmoid sinus, anterior ethmoidal artery, posterior ethmoidal artery and anterior skull base were observed. Artificial anatomy was performed and the deep-seated regions of the surgical approach were observed under operating microscope and endoscope. Examined from the intracranial and intranasal aspects, it was found that the middle turbinate, uncinate process, ethmoid bulla, lamina papyracea, anterior ethmoid canal, posterior ethmoid canal, prominence of the optic canal and opticocarotid recess were all important anatomic landmarks for surgery. The horizontal distances between medial orbital wall on both sides at the level of crista galli, anterior ethmoid canal, and posterior ethmoid canal were (22.31 ± 3.08) mm, (23 ± 2.93) mm, and (26.25 ± 2.88) mm, respectively. The distance between the double optic canal cranial opening was (14.67 ± 3.82) mm. During the endonasal approach for anterior skull base surgery, full advantage of the surgical corridor made by the middle turbinate resection should be taken. To control intraoperative bleeding, it is critical to identify anterior and posterior ethmoidal artery. Identification and protection of medial orbital wall and the optic nerve, and controlling the ranges of anterior basicranial craniotomy are of great importance for surgical safety.

Resection of pineal region tumors in children through modified Poppen approach

Objective To evaluate the efficiency and safety of the surgical procedure to deal with the tumors in pineal region of children.Methods 9 children who suffered from the pineal region tumors received the modified Poppen approach in TianjinHuanhu hospital from January 2008 to October 2011.Three main techniques were included in the reformative Poppen approach:straight incision of scalp starting from the external occipital jut and then extending just between the lines of transversesinus and superiorsagittal sinus for 5 ～ 7 cm,a little rounded skull window with a diameter of 3.5 cm,and instead of along the straight sinus as the classical Poppen approach,the tentorial was incised just from the confluence of sinus and then agley go to the tentorial edge.The results were evaluated with indexes such as the rate of gross total resection (GTR) of tumors,the complication derived from the approach,the duration between cranial opening and closing.Results The GTR was 77.8％.The rate of bridging vein injury was 11.1％.The homonymous hemianopia rate was 22.2％.The duration between cranial opening and closing was ( 25.4 ± 4.4 ) mins.There was no death.Conclusions The modified Poppen approach could offer enough visual field and space to resect the pineal region tumorsof children drasticallyand safely. Key words: Children; Pineal region tumor; Poppen approach

Unruptured Supraclinoid Internal Carotid Artery Aneurysm Surgery : Superciliary Keyhole Approach versus Pterional Approach

ObjectiveA superciliary keyhole approach is an attractive, minimally invasive surgical technique, yet the procedure is limited due to a small cranial opening. Nonetheless, an unruptured supraclinoid internal carotid artery (ICA) aneurysm can be an optimal surgical target of a superciliary approach as it is located in the center of the surgical view and field. Therefore, this study evaluated the feasibility and surgical outcomes of a superciliary keyhole approach for unruptured ICA aneurysms.MethodsThe authors report on a consecutive series of patients who underwent a superciliary approach for clipping unruptured ICA aneurysms between January 2007 and February 2012. The data were compared with a historical control group who underwent a pterional approach between January 2003 and December 2006.ResultsIn the superciliary group, a total of 71 aneurysms were successfully clipped without a residual sac in 70 patients with a mean age of 57 years (range, 37-75 years). The maximum diameter of the aneurysms ranged from 4 mm to 14 mm (mean±standard deviation, 6.6±2.3 mm). No direct mortality or permanent morbidity was related to the surgery. The superciliary approach demonstrated statistically significant advantages over the pterional approach, including a shorter operative duration (mean, 100 min), no intraoperative blood transfusions, and no postoperative epidural hemorrhages.ConclusionA superciliary keyhole approach provides a sufficient surgical corridor to clip most unruptured supraclinoid ICA aneurysms in a minimally invasive manner.

Photoacoustic microscopy of microvascular responses to cortical electrical stimulation

Advances in the functional imaging of cortical hemodynamics have greatly facilitated the understanding of neurovascular coupling. In this study, label-free optical-resolution photoacoustic microscopy (OR-PAM) was used to monitor microvascular responses to direct electrical stimulations of the mouse somatosensory cortex through a cranial opening. The responses appeared in two forms: vasoconstriction and vasodilatation. The transition between these two forms of response was observed in single vessels by varying the stimulation intensity. Marked correlation was found between the current-dependent responses of two daughter vessels bifurcating from the same parent vessel. Statistical analysis of twenty-seven vessels from three different animals further characterized the spatial-temporal features and the current dependence of the microvascular response. Our results demonstrate that OR-PAM is a valuable tool to study neurovascular coupling at the microscopic level.

Intraoperative Intracerebral MRI-Guided Navigation for Accurate Targeting in Nonhuman Primates

During in vivo intracerebral infusions, the ability to perform accurate targeting towards a 3D-specific point allows control of the anatomical variable and identification of the effects of variations in other factors. Intraoperative MRI navigation systems are currently being used in the clinic, yet their use in nonhuman primates and MRI monitoring of intracerebral infusions has not been reported. In this study rhesus monkeys were placed in a MRI-compatible stereotaxic frame. T1 MRIs in the three planes were obtained in a 3.0T GE scanner to identify the target and plan the trajectory to ventral postcommisural putamen. A craniotomy was performed under sterile surgical conditions at the trajectory entry point. A modified MRI-compatible trajectory guide base (Medtronic Inc.) was secured above the cranial opening and the alignment stem applied. Scans were taken to define the position of the alignment stem. When the projection of the catheter in the three planes matched the desired trajectory to the target, the base was locked in position. A catheter replaced the alignment stem and was slowly introduced to the final target structure. Additional scans were performed to confirm trajectory and during the infusion of a solution of gadoteridol (ProHance, Bracco Diagnostics; 2 mM/L) and bromophenol blue (0.16 mg/ml) in saline. Monitoring of the pressure in the infusion lines was performed using pressure monitoring and infusion pump controller system (Engineering Resources Group Inc.) in combination with a MRI-compatible infusion pump (Harvard). MRI during infusion confirmed successful targeting and matched postmortem visualization of bromophenol blue. Assessment of the accuracy of the targeting revealed an overall 3D mean ± SD distance error of 1.2 ± 0.6 mm and angular distance error of 0.9 ± 0.5 mm. Our results in nonhuman primates confirm the accuracy of intraoperative MRI intracerebral navigation combined with an adaptable, pivot point-based targeting system and validates its use for preclinical intracerebral procedures.

The applied anatomical study for transethmoidal-sphenoid optic nerve decompression under endoscopy

Objective To explore the anatomy for transethmoidal-sphenoid optic nerve decompression under endoscopy and its significance in operation. Methods Fifteen cases (30 sides) of formalin-fixed adult optic canal specimens were dissected under the microscope. The anatomic characteristics of the optic canal and its adjacent were observed, and the relative parameters were evaluated according to nasal endoscopic approach. Results ①The relationship between the optic carotid triangle(OCT)with the optic canal, the ophthalmic artery, the cavernous sinus and the internal carotid artery were invariable, its present ratio were in 66.7%. ②The mean distance from the front margin of nasal columella floor to medial wall of the orbital opening, middle portion and the cranial opening in the optic canal were (72.79 ± 5.40)mm, (75.85 ± 5.10)mm and (79.34 ± 4.95)mm, respectively, and the elevation angles were (39.45 ± 3.68)°, (37.30±4.24)°and (35.45 ± 4.16)°, respectively. ③The mean thickness of sheath in the medial wall of the orbital opening,middle portion and the cranial opening were (0.70 ± 0. 18)mm, (0.51 ± 0.15)mm and (0.49-0.22)mm,respectively. The difference in thickness between the orbital opening and middle portion, the cranial opening were very remarkable(P ＜ 0.01 ). ④The lateral deviate distance from medial wall of the orbital opening, middle portion and cranial opening to sagittal median plane of cadaveric were 1/2 (12.69 ± 2.73)mm、1/2( 19.61± 3.47)mm and 1/2 (25.79 ± 3.23)mm, respectively. Conclusion OCT is the most reliable anatomic landmark to locate the optic canal, and the key point is at the orbital opening of the optic nerve in the optic nerve decompression. It is secure and feasible to cut the sheath from the place where the medial wall crosses the superior wall of the optic nerve. Key words: Optic nerve decompression; Optic carotid triangle; Transethmoidal-sphenoid approach; Endoscopy; Applied anatomy

Preoperative or preembolization lesion targeting using rotational angiographic fiducial marking in the neuroendovascular suite

Three-dimensional rotational digital subtraction (DS) angiography and DynaCT allow precise localization of intracranial arteriovenous fistulas (AVFs) with fiducial markers that have helped in surgical planning. These techniques are particularly useful when the AVF is not evident on cross-sectional imaging. The authors demonstrate the utility of 3D DS angiography and DynaCT in the localization of intracranial AVFs in 3 cases. Their first case was a dural AVF with multiple arterial feeders from the left occipital artery that drained into the left transverse sinus. Blood flow to the left transverse sinus was first decreased by embolizing the branch arterial feeders with polyvinyl alcohol particles. Thereafter, 3D DS angiography enabled precise localization of the site for the bur hole creation with a fiducial to allow access for the transverse sinus in the second part of the procedure where definitive transvenous sinus embolization of the dural AVF with coils was performed. They also used 3D DS angiography and DynaCT with fiducials for precise localization of a superficial pial AVF (Case 2) and a tentorial AVF (Case 3) not visible on cross-sectional angiography. With the precise localization of the target lesion, the neurosurgeons were able to perform relatively small craniotomies, minimizing the cranial opening yet allowing the opening for full access to the lesion. By correlating 3D DS angiography/DynaCT with CT images, the neurosurgeon could use neuronavigation in cases of AVF not appreciated on cross-sectional imaging.

Two surgical methods used in 90 patients with intracranial subdural empyema

We studied the efficacy of two surgical methods used for the treatment of intracranial subdural empyema (ISDE) at our centre. A cross-sectional study (1999–2005) of 90 patients with non-traumatic supratentorial ISDE revealed that the two surgical methods used for empyema removal were burr hole/s and drainage (50 patients, 55.6%) and a cranial bone opening procedure (CBOP) (40 patients, 44.4%). Patients in the CBOP group had a better result in terms of clinical improvement (chi-squared analysis, p = 0.006) and clearance of empyema on brain CT scan (chi-squared analysis, p < 0.001). Reoperation was more frequent among patients who had undergone burr hole surgery (multiple logistic regression, p < 0.001). The outcome and morbidity of ISDE survivors were not related to the surgical method used ( p > 0.05). The only factor that significantly affected the morbidity of ISDE was level of consciousness at the time of surgery (multiple logistic regression, p < 0.001). We conclude that CBOP and evacuation of the empyema is a better surgical method for ISDE than burr hole/s and drainage. Wide cranial opening and empyema evacuation improves neurological status, gives better clearance of the empyema and reduces the need for reoperation. Level of consciousness at the time of presentation is a predictor of the morbidity of ISDE. Thus, aggressive surgical treatment should occur as early as possible, before the patient deteriorates.

Opening cranial cisterns in anterior subtemporal keyhole approach to superior petroclival region:anatomic study and comparative analysis

Objective To quantitatively compare the exposure areas and angles in anterior subtemporal keyhole approach to superior petroclival region before and after cranial cisterns opening. Methods The study was carried out on 20 sides of cadaver heads. With application of a navigation system, the exposure area in superior clivus, the ventrolateral area in brain stem around BA, the linear exposure of the posterior petroclinoid fold and BA trunk, and the approach angles to BA tip were evaluated. Results The exposure area in superior clivus （ 136. 7 ± 19. 8 ） mm^2, the ventrolateral area in brain stem （ 222. 8 ± 25.8 ） mm^2, the linear exposure of the posterior petroclinoid fold （ 11.5 ±0. 6 ） mm, and BA trunk （10. 3± 2.0 ）mm, and the approach angles in the vertical axis to BA tip（ 13.7 ± 1.7 ）°were significantly greater after opening cranial nerve cisterns. But the approach angles in the horizontal axis to BA tip were indifferent. Conclusions The exposure areas and angles of anterior subtemporal keyhole approach to superior petroclival region can be increased after opening cranial nerve cisterns. Key words: Subtemporal; Keyhole approach; Cranial nerve cisterns ; Superior petroclival region

Cerebral hydatid cysts: technique and pitfalls of surgical management

Hydatid cysts are rare, but most often they occur in the liver and lungs. Cerebral manifestation is very rare, and surgery is the main treatment. The goal of surgery is to remove the cysts in toto without rupture. The aim of this study was to investigate the surgical technique of removing cerebral hydatid cysts and to show the possible pitfalls of surgery. This study included 17 patients who underwent surgery for an intracranial hydatid cyst. The Dowling technique was used in all patients. This technique is based on the large cranial opening, careful handling, meticulous cortical dissection, and removal of the cyst by hydrostatic assistance. The hydatid cysts were removed unruptured in 88% of the cases. The cysts ruptured intraoperatively in 2 patients, and the ventricular system was opened in 1 of them. Anaphylactic reaction or chemical meningitis did not occur, but recurrence and spinal seeding were observed in the follow-up of these patients. The thin cyst wall, periventricular locations, and microadhesions to the surrounding brain tissue were the main surgical problems. None of the patients died after the surgery. Although this technique seems safe and easy, there are some pitfalls concerning the cyst location and surgical approach. Successful management requires a flexible therapeutic strategy and meticulous dissection by an experienced surgeon.

The dysraphic levels of skin and vertebrae are different in mouse fetuses and neonates with myelomeningocele

Background Mouse fetuses with spontaneous myelomeningocele (MMC) were investigated, determining the various levels of dysraphism in soft tissue, spinal cord, and vertebrae. Morphology was correlated with hind limb function. Methods Viable curly tail/ loop tail mouse fetuses underwent qualitative standardized ex utero examination of tail and hind limb sensitivity and motor response. Afterward, they were processed either for histology or skeletal preparation. Results All animals displayed identical cranial levels of soft tissue and neural defects. The cranial opening of the vertebral defects were invariably located more cranially (range, 0.5-5 vertebrae; mean = 2.25). The caudal opening of soft/neural tissue and bony defects was invariably at the coccygeal base. The comparison of functional with morphological levels demonstrated that, in 52.5%, the level of the soft/neural tissue dysraphism and, in 47.5%, the level of the bony opening correlated with the neurologic deficit. Conclusion The naturally occurring soft tissue coverage over the MMC could exert a protective effect toward the underlying spinal cord. This interpretation supports the concept that in utero acquired destruction of exposed neural tissue is a main factor for the neonatal functional deficit. Thus, these data are consistent with the rationale for prenatal MMC repair in humans.

Electrophysiological monitoring in a patient with an optic nerve glioma

To report a case illustrating the value of pattern VEP and pattern ERG (PERG) in monitoring optic nerve gliomata (OG). A 15-year-old girl presented with a 3-year history of frontal headaches and a 5-month history of blurred vision in the right eye. MRI scanning revealed a thickened, right optic nerve extending to the cranial opening of the optic canal, consistent with an optic nerve glioma. Pattern VEP showed a mildly delayed major positive component consistent with optic nerve dysfunction. The PERG N95:P50 ratio was subnormal in keeping with retinal ganglion cell involvement. Visual acuity decreased over the following 2 years and repeat VEP objectively demonstrated marked deterioration in optic nerve function despite neuroradiology showing no significant change in the tumour. Pattern VEPs and pattern ERGs can provide early objective evidence of optic nerve/retinal ganglion cell dysfunction in optic nerve gliomata. Serial recordings can objectively demonstrate worsening function in the absence of significant neuroradiological change.