Myelomeningocele repair

The closure of the skin defect in myelomeningocele (MMC) repair is an essential step that determines the quality of the surgical result. The success of surgical results is related to the decision to use the most suitable techniques, namely flaps or primary closure.

In cases of myelomeningocele, some prefer to place the shunt and close the defect in the same procedure, it reduces the risks inherent to exposure to anesthesia, reduces hospital stay, and related costs. If there is a suspicious of infection, they do not place the shunt on the same procedure 1).

Prenatal therapeutic strategies that interrupt progressive pathological processes offer an appealing approach for treatment of MMC. However, a thorough understanding of pathological progression of MMC is mandatory for appropriate treatment to be rendered 2).

Closure of the defect.

MOMS Trial

see MOMS Trial.

Case series

A prospective study of Zarutskie et al., from the Baylor College of MedicineTexas Children’s HospitalLucile Packard Children’s Hospital Stanfordfrom fetuses diagnosed with open neural tube defect that had in-utero myelomeningocele repair between April 2014 and April 2016. Independent variables were collected from four chronological sets of fetal images: pre-surgery ultrasound, pre-surgery MRI, 6-week post-surgery MRI and pre-delivery ultrasound. The following independent variables were collected from all image sets unless otherwise noted: gestational age, head circumference, mean ventricular width, ventricular volume (VV, MRI only), hindbrain herniation (HBH) score (MRI only), and level of lesion, defined as the upper bony spinal defect (pre-surgery US). Based on these measurements, additional variables were defined and calculated including change in degree of HBH, ventricular width growth (mm/week), and ventricular volume growth (ml/week). The need for hydrocephalus HT (by either ventriculoperitoneal shunt or endoscopic third ventriculostomy and choroid plexus cauterization (ETV-CPC)) was determined by a pediatric neurosurgeon using clinical and radiographic criteria; a secondary analysis was performed using the MOMS trial criteria for hydrocephalus. The predictive value of each parameter was assessed by ROC-curve and logistic regression analyses.

Fifty affected fetuses were included in the study, of which 32 underwent open hysterotomy and 18 fetoscopic repair. Two cases of neonatal death were excluded from the analysis. The mean gestational ages for the pre-surgery ultrasound, pre-surgery MRI, post-surgery MRI and pre-delivery ultrasound were 21.8 ± 2.1 weeks, 22.0 ±1.8 weeks, 30.4 ±1.6 weeks and 31.0 ±4.9 weeks, respectively. A total of 16 subjects required HT. Area under the curve (AUC) of predictive accuracy for HT showed that HBH grading on post-surgery MRI had the strongest predictive value (0.86; p<0.01), outperforming other predictors such as mean ventricular width on pre-surgery US (0.67; p=0.05), post-surgery MRI VV (0.73; p=0.03), MRI VV growth (0.79; p=0.01), change in HBH (0.82; p<0.01), and mean ventricular width on pre-delivery US (0.73; p=0.01). Other variables such as mean ventricular width on pre-surgery and post-surgery MRI, and ventricular growth assessment by MRI or US, had an AUC<0.7. Optimal cut-offs of the variables with the highest AUCs were evaluated to improve prediction. A combination of ventricular volume growth ≥ 2.02 ml/week and/or HBH of 3 on post-surgery MRI were the optimal cut-offs for the best prediction [OR: 42 (95% CI: 4 – 431), accuracy: 84%]. Logistic regression analyses also showed that persistence of severe HBH 6 weeks after surgery by MRI is one of the best predictors for HT [OR 39 (95% CI: 4 – 369), accuracy: 84%]. There was no significant change in the results when the MOMS trial criteria for hydrocephalus were used as the dependent variable 3).


Sanz-Cortés et al., described and compared placental and amniotic histology in women who underwent a fetoscopic myelomeningocele repair to those who underwent an open-hysterotomy myelomeningocele repair. Also, we intended to compare findings from both prenatal repair groups to age-matched control pregnant patients.

Placental and membrane histopathology from 43 prenatally repaired spina bifida cases (17 fetoscopic and 26 open) and 18 healthy controls were retrospectively assessed. Quantitative assessment of histopathology included apoptosis count, maternal and fetal underperfusion scores. Qualitative assessment included the detection of pigmented macrophages and/or signs of placental/amniotic inflammation. Associations between the duration of surgery or the duration of CO2 insufflation and quantitative histological parameters were tested.

Fetoscopic surgery cases did not show significant differences in any of the studied parameters when compared against controls. No differences were detected either when compared to open-repaired cases, except for lower proportion of pigmented laden macrophages in the fetoscopic group (11.8% vs 61.5% p<0.01). No associations between the duration of surgery or the duration of CO2 exposure and any of the quantitative histological parameters were detected.

These preliminary results support the lack of detrimental effects of the use of heated and humidified CO2 gas for uterine insufflation to fetal membranes and placenta 4).

References

1)

Bao N, Lazareff J. How I Do It: Management of spina bifida in a hospital in The People’s Republic of China. Surg Neurol Int. 2015 Jul 23;6(Suppl 11):S337-45. doi: 10.4103/2152-7806.161410. eCollection 2015. PubMed PMID: 26236554; PubMed Central PMCID: PMC4521313.
2)

Smith GM, Krynska B. Myelomeningocele: How we can improve the assessment of the most severe form of spina bifida. Brain Res. 2014 Dec 9. pii: S0006-8993(14)01659-X. doi: 10.1016/j.brainres.2014.11.053. [Epub ahead of print] PubMed PMID: 25498106.
3)

Zarutskie A, Guimaraes C, Yepez M, Torres P, Shetty A, Sangi-Haghpeykar H, Lee W, Espinoza J, Shamshirsaz A, Nassr A, Belfort M, Whitehead W, Sanz Cortes M. Prenatal brain imaging for predicting postnatal hydrocephalus treatment in fetuses that had neural tube defect repair. Ultrasound Obstet Gynecol. 2019 Jan 8. doi: 10.1002/uog.20212. [Epub ahead of print] PubMed PMID: 30620440.
4)

Sanz-Cortés M, Castro E, Sharhan D, Torres P, Yepez M, Espinoza J, Shamshirsaz AA, Nassr AA, Popek E, Whitehead W, Belfort MA. AMNIOTIC MEMBRANE AND PLACENTAL HISTOPATHOLOGICAL FINDINGS AFTER OPEN AND FETOSCOPIC PRENATAL NEURAL TUBE DEFECT REPAIR. Prenat Diagn. 2019 Jan 4. doi: 10.1002/pd.5414. [Epub ahead of print] PubMed PMID: 30609053.

Dorsal root ganglion stimulation

Neuromodulation of distal targets such as dorsal root ganglion may permit greater anatomic specificity of the therapy, whereas subthreshold stimulation with high-frequency or burst energy delivery may eliminate noxious and off-target paresthesiae. Such new technologies should be subject to rigorous evaluation as their mechanisms of action and long-term outcomes remain hitherto undefined 1).

Indications

Case series

Piedade et al., from University Hospital of Düsseldorf, reported a consecutive series of 20 patients treated with DRG stimulation in the upper thoracic and cervical region. All patients suffered from chronic neuropathic pain unresponsive to best medical treatment. Main pain etiologies were traumaspine surgerypostherpetic neuralgia, and peripheral nerve surgery. All patients were trialed with externalized electrodes prior to permanent pulse generator implantation. Routine clinical follow-up was performed during reprogramming sessions.

Out of all 20 patients trialed, 18 were successfully trialed and implanted with a permanent stimulation system. The average pain relief after three months compared to the baseline was of 60.9% (mean VAS 8.5 to VAS 3.2). 77.8% of the patients reported a pain relief of at least 50% after three months. One patient developed a transient paresis of the arm caused by the procedure. She completely recovered within three months.

Cervical and upper thoracic DRG stimulation resulted in good overall response rates to trialing and similar pain relief when compared to DRG stimulation for groin and lower limb pain. A modified surgical approach has to be used when compared with lumbar DRG electrode placement. Surgery itself in this region is more complication prone and challenging 2).


Morgalla et al., prospectively enrolled 12 adult patients with unilateral localized neuropathic pain in the lower limbs or inguinal region and followed them up for six months Laser evoked potentials (LEP) were assessed at baseline, after one month of DRGS, and after six months of DRGS. Clinical assessment included the Numerical Rating Scale (NRS), Brief Pain Inventory (BPI), SF-36, and Beck Depression Inventory (BDI). For each patient, LEP amplitudes and latencies of the N2 and P2 components on the deafferented side were measured and compared to those of the healthy side and correlated with pain intensity, as measured with the NRS.

At the one- and six-month follow-ups, N2-P2 amplitudes were significantly greater and NRS scores were significantly lower compared with baseline (all p’s < 0.01). There was a negative correlation between LEP amplitudes and NRS scores (rs = -0.31, p < 0.10).

DRGS is able to restore LEPs to normal values in patients with localized neuropathic pain, and LEP alterations are correlated with clinical response in terms of pain intensity 3).

Case reports

van Velsen et al. used a single-incision approach to tunnel and implant the leads and pulse generator for DRG stimulation treatment in a patient suffering from intractable foot pain. At long-term follow-up, the patient experienced a decrease in pain intensity and improvement in function, without any complications. A single-incision implantation technique for DRG stimulator implantation may simplify implantation and decrease the risk of complications 4).

References

1)

Shamji MF, De Vos C, Sharan A. The Advancing Role of Neuromodulation for the Management of Chronic Treatment-Refractory Pain. Neurosurgery. 2017 Mar 1;80(3S):S108-S113. doi: 10.1093/neuros/nyw047. PubMed PMID: 28350939.
2)

Piedade GS, Vesper J, Chatzikalfas A, Slotty PJ. Cervical and High-Thoracic Dorsal Root Ganglion Stimulation in Chronic Neuropathic Pain. Neuromodulation. 2019 Jan 8. doi: 10.1111/ner.12916. [Epub ahead of print] PubMed PMID: 30620789.
3)

Morgalla MH, de Barros Filho MF, Chander BS, Soekadar SR, Tatagiba M, Lepski G. Neurophysiological Effects of Dorsal Root Ganglion Stimulation (DRGS) in Pain Processing at the Cortical Level. Neuromodulation. 2018 Dec 18. doi: 10.1111/ner.12900. [Epub ahead of print] PubMed PMID: 30561852.
4)

van Velsen V, van Helmond N, Levine ME, Chapman KB. Single-Incision Approach to Implantation of the Pulse Generator and Leads for Dorsal Root Ganglion Stimulation: A Case Report. A A Case Rep. 2017 Aug 14. doi: 10.1213/XAA.0000000000000625. [Epub ahead of print] PubMed PMID: 28816708.

Petrous pyramid

The petrous part of the temporal bone is pyramid-shaped and is wedged in at the base of the skull between the sphenoid and occipital bones. Directed medially, forward, and a little upward, it presents a base, an apex, three surfaces, and three angles, and houses in its interior, the components of the inner ear.

The ventral surface of the brain stem is anatomically surrounded by the clivusanteriorly, brain stem posteriorly and by the petrous pyramid and cranial nerves from IIIrd to XIIth laterally in the deep posterior cranial fossa.

The endolymphatic sac is located in a duplication of the dura of the posterior aspect of the petrous pyramid and is, therefore, in the surgical field of many neurosurgical operations performed on the posterolateral cranial base.

Surgical anatomy of the petrous pyramid has always been a challenge, especially in the beginning of the training process. Providing an easier, holistic approach can be of help to everyone with interest in learning and teaching skull base anatomy.


Tawfik-Helika et al., from the Department of Neurosurgery, Beaujon HospitalPierre Wertheimer Hospital, Department of Surgery, University of São Paulo Sorbonne Université, Paris, Department of Neurosurgery, Addenbrooke’s Hospital, presented the complex organization of the petrous pyramid anatomy using a new compartmental approach that is simple to understand and remember.

The contents of the petrous pyramid of eight temporal bones were exposed through progressive drilling of the superior surface.

The petrous pyramid is made of a bony container, while its contents were grouped into four compartments (mucosal, cutaneous, neural and vascular). Two reference lines were identified (mucosal and external-internal auditory canal lines) intersecting at the level of the middle ear. The localization of contents relative to these reference lines was then described and two methods of segmentation; the X-method and V-method, were then proposed. This description was then used to describe middle ear relationships, facial nerve anatomy and air cell distribution.

This new simple compartmental approach allows a comprehensive understanding of the distribution of petrous pyramid contents. Dividing it into anatomical compartments, and then navigating this mental map along specific reference points, lines, spaces, and segments could bring a useful tool to teach or learn its complex tridimensional anatomy 1).


Posterior petrous meningiomas (commonly termed posterior pyramid meningiomas and/or meningiomas of the posterior surface of the petrous pyramid) are the most common meningiomas of the posterior cranial fossa.


Drilling of the posterior pyramidal wall is facilitated on identification of the intersection of the petrous ridge with the most anterior portion of the bone ledge covering the sigmoid sinus (petrosigmoid intersection), the bony operculum of the endolymphatic sac, and the petrous ridge. Drilling may proceed rather safely at a minimum depth of 2.5 mm in an area 0.9 cm anterior and 1 cm inferior to the petrosigmoid intersection and petrous ridge, respectively. From there, identification of the vestibular aqueduct, genu, and horizontal portion is necessary to safely open the posterior wall of the internal auditory canal. The vestibular aqueduct represents the lateral and superior limits of drilling. The bone between these areas may then be safely drilled to a depth of at least 2.5 mm. A microneurosurgical dissection of the posterior pyramidal wall conducted in cadaveric material according to these guidelines did not violate any inner-ear structures 2).


Transtemporal supralabyrinthine approach is a modified middle cranial fossa approach. It offers all the advantages of a middle cranial fossa procedure and avoids its disadvantages, mainly the extensive temporal lobe retraction and frightening complications. The principle of the approach is to gain sufficient access toward the internal auditory canal by removing bone from the roof of the petrous pyramid rather than by elevating the middle fossa dura away from it. Fifteen patients underwent this approach for decompression of paralysed facial nerve resulted from temporal bone fracture, Bell’s palsy and herpes zoster oticus; for removal of facial neuromas and primary cholesteatomas in temporal bone and for sectioning of great superficial petrous nerve. Preliminary study showed good results 3).

References

1)

Tawfik-Helika M, Mertens P, Ribas G, Catala M, Kirollos R, Jacquesson T. Understanding anatomy of the petrous pyramid – a new compartmental approach. World Neurosurg. 2019 Jan 5. pii: S1878-8750(18)32795-5. doi: 10.1016/j.wneu.2018.11.234. [Epub ahead of print] PubMed PMID: 30620892.
2)

Ammirati M, Ma J, Cheatham ML, Maxwell D, Bloch J, Becker DP. Drilling the posterior wall of the petrous pyramid: a microneurosurgical anatomical study. J Neurosurg. 1993 Mar;78(3):452-5. PubMed PMID: 8433148.
3)

Zhao JC. [Transtemporal supralabyrinthine approach]. Zhonghua Er Bi Yan Hou Ke Za Zhi. 1992;27(6):342-4, 382. Chinese. PubMed PMID: 1303667.
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