Convexity meningioma surgery

Convexity meningioma surgery

Convexity meningioma surgery indications.

Preoperative embolization of intracranial meningioma.

see Surgical safety checklist.

see Preoperative antibiotic prophylaxis.

see Skin Preparation.

For convexity meningioma, the head is positioned so that the center of the tumor is uppermost, the same position as described for parasagittal tumors or for tumors close to the midline.

The incision and bone flap must be large enough to allow for excision of a good margin of dura around the tumor attachments.

The meningeal arteries are occluded as they are exposed.

These tumors can be removed intact by placing gentle traction on the dural attachment and working circumferentially around the tumor to divide the attachments to the cortex. However, if the surface of the tumor cannot be easily visualized without placing significant retraction on the cortex, internal decompression of the tumor is done and the capsule is reflected into the area of decompression.

In a situation where the tumor arises over the frontal temporal junction and grows into the sylvian fissure, the medial capsule and the dural attachment may extend down onto the lateral floor of the anterior fossa and anterior wall of the middle fossa, and the medial capsule of the tumor can be attached to branches of the middle cerebral artery.

A study showed that meningioma recurrence was unlikely when autologous cranioplasty was done with refashioned hyperostotic bone. This could be done in the same setting with meningioma excision. There was no recurrence at a mean of 5-year follow-up in convexity meningiomas 1).

Right Convexity Meningioma from Surgical Neurology International on Vimeo.

Left Frontal Convexity Meningioma from Surgical Neurology International on Vimeo.

An accurate and real-time model of soft tissue is critical for surgical simulation for which a user interacts haptically and visually with simulated patients. A paper focuses on the real-time deformation model of brain tissue for the interactive surgical simulation, such as neurosurgical simulation.

A new Finite Element Method (FEM) based model with constraints is proposed for the brain tissue in neurosurgical simulation. A new energy function of constraints characterizing the interaction between the virtual instrument and the soft tissue is incorporated into the optimization problem derived from the implicit integration scheme. Distance and permanent deformation constraints are introduced to describe the interaction in the convexity meningioma dissection and hemostasis. The proposed model is particularly suitable for GPU-based computing, making it possible to achieve real-time performance.

Simulation results show that the simulated soft tissue exhibits the behaviors of adhesion and permanent deformation under the constraints. Experiments show that the proposed model is able to converge to the exact solution of the implicit Euler method after 96 iterations. The proposed model was implemented in the development of a neurosurgical simulator, in which surgical procedures such as dissection of convexity meningioma and hemostasis were simulated 2).


1)

Lau BL, Che Othman MI, Fakhri M, San Liew DN, San Lim S, Bujang MA, Hieng Wong AS. Does putting back hyperostotic bone flap in meningioma surgery causes tumor recurrence? An observational prospective study. World Neurosurg. 2019 Mar 26. pii: S1878-8750(19)30863-0. doi: 10.1016/j.wneu.2019.03.183. [Epub ahead of print] PubMed PMID: 30926555.
2)

Hou W, Liu PX, Zheng M. A new model of soft tissue with constraints for interactive surgical simulation. Comput Methods Programs Biomed. 2019 Jul;175:35-43. doi: 10.1016/j.cmpb.2019.03.018. Epub 2019 Apr 1. PubMed PMID: 31104713.

Microvascular decompression for hemifacial spasm outcome

Microvascular decompression for hemifacial spasm outcome

Microvascular decompression is an effective treatment option in elderly patients with hemifacial spasm as well as in younger patients. Age itself seems to be no relevant contraindication or, alternatively, risk factor regarding MVD 1)

Given that postoperative delayed cure was unavoidable, even with accurate identification of the offending vessel and sufficient decompression of the root exit zone, the delayed cure should be considered in patients undergoing reoperation due to lack of remission or relapse after the operation. Additionally, the timing of efficacy assessments should be delayed 2).

The definitive treatment for hemifacial spasm is microvascular decompression (MVD), which cures the disease in 85% to 95% of patients according to reported series. In expert hands, the MVD procedure can be done with relatively low morbidity.

Post-operatively, there may be episodes of mild HFS, however they usually begin to diminish 2–3 days following MVD. Severe spasm that does not abate suggests failure to achieve adequate decompression, and reoperation should be considered.

Surgical results of MVD depends on the duration of symptoms (shorter duration has better prognosis) as well as on the age of the patient (elderly patients do less well). Complete resolution of HFS occurred in 44 (81%) of 54 patients undergoing MVD, however, 6 of these patients had relapse 3). 5 patients (9%) had partial improvement, and 5 (9%) had no relief.


Complete resolution of spasm occurs in ≈ 85–93% 4) 5) 6) 7) 8). Spasm is diminished in 9%, and unchanged in 6% 9). Of 29 patients with complete relief, 25 (86%) had immediate post-op resolution, and the remaining 4 patients took from 3 mos to 3 yrs to attain quiescence.

Recurrent hemifacial spasm after microvascular decompression.


1)

Zhao H, Zhu J, Tang YD, Shen L, Li ST. Hemifacial Spasm: Comparison of Results between Patients Older and Younger than 70 Years Operated on with Microvascular Decompression. J Neurol Surg A Cent Eur Neurosurg. 2021 Jul 8. doi: 10.1055/s-0040-1721018. Epub ahead of print. PMID: 34237777.
2)

Li MW, Jiang XF, Wu M, He F, Niu C. Clinical Research on Delayed Cure after Microvascular Decompression for Hemifacial Spasm. J Neurol Surg A Cent Eur Neurosurg. 2019 Oct 10. doi: 10.1055/s-0039-1698461. [Epub ahead of print] PubMed PMID: 31600810.
3)

Auger RG, Peipgras DG, Laws ER. Hemifacial Spasm: Results of Microvascular Decompression of the Facial Nerve in 54 Patients. Mayo Clin Proc. 1986; 61:640–644
4)

Rhoton AL. Comment on Payner T D and Tew J M: Recurren ce of Hemifacial Spasm After Microvascular Decompression. Neurosurgery. 1996; 38
5)

Jannetta PJ. Neurovascular Compression in Cranial Nerve and Systemic Disease. Ann Surg. 1980; 192:518–525
6)

Loeser JD, Chen J. Hemifacial Spasm: Treatment by Microsurgical Facial Nerve Decompression. Neurosurgery. 1983; 13:141–146
7)

Huang CI, Chen IH, Lee LS. Microvascular Decompression for Hemifacial Spasm: Analyses of Operative Findings and Results in 310 Patients. Neurosurgery. 1992; 30:53–57
8) , 9)

Payner TD, Tew JM. Recurrence of Hemifacial Spasm After Microvascular Decompression. Neurosurgery. 1996; 38:686–691

Nerve root retraction

Nerve root retraction

Findings showed that posterior lumbar procedures, including retraction of paravertebral muscle, fenestration of the lamina, and retraction of the nerve root affect the posterior ramus. Excessive retraction of the nerve root has an especially disastrous effect on the posterior ramus. Such a violent maneuver within the spinal canal must be avoided 1).


Feltes et al. studied whether the amount of retraction pressure applied to a compromised nerve root during lumbar discectomy has an impact on intra- or postoperative outcomes.

The authors conducted a prospective analysis of 20 patients. There were 12 men and 12 women whose mean age (+/- standard deviation [SD]) was 42.25 years +/- 15 years (range 21-65 years). During intraoperative electromyography (EMG) monitoring, measurements were obtained during routine retraction of the affected nerve root by using a specially designed and constructed nerve root retractor connected to a reconfigured personal computer for this specific purpose. Follow-up results were assessed in the immediate postoperative period and at up to 1 year. The maximum measured force applied during random periods of time was 9.85 N/second (mean 6.95 +/- N/second [+/- SD]). The mean retraction time was 39.5 +/- 21 (SD). No intraoperative EMG-detected irritation was noted during or after routine retraction. In four of 20 patients, sensory changes occurred at the ipsilateral nerve root level, which resolved at the time of discharge.

The authors found that routine nerve root retraction does not cause nerve root irritation, as demonstrated by EMG monitoring, nor was patient outcome affected in this series 2).


The aim of a retrospective case study was to analyze the outcomes of minimal nerve root retraction in patients with an impending neurologic deficit in degenerative lumbar spine disease using full-endoscopic spine surgery.

Thirty-seven consecutive patients with impending neurologic deficit underwent endoscopic spine surgery through either the transforaminal or the interlaminar approach. Their clinical outcomes were evaluated with visual analog scale (VAS) leg pain score, Oswestry Disability Index (ODI), and MacNab scale score. The outcome of motor deficits were evaluated with the Medical Research Council Scale for Muscle Strength grade. Completeness of decompression was documented with a postoperative magnetic resonance imaging (MRI) and computed tomography (CT) scan.

A total of 40 lumbar levels of 37 patients were operated on, VAS score of the leg improved from 7.7 ± 1 to 1.9 ± 0.6 (p < 0.0001). ODI score improved from 74.7 ± 6.5 to 25.4 ± 3.49 (p < 0.0001). Motor weakness improved significantly immediately after surgery. The mean MRC grade increased to 1.97, 3.65, 4.41, and 4.76 preoperatively, at 1 week, at 3 months, and at the final follow-up, respectively, and all the patients with foot drop and cauda equina syndrome symptoms recovered completely. One patient with great toe drop recovered partially to MRC grade 3. The mean follow-up of the study was 13.3 ± 6.1 months. According to MacNab’s criteria, 30 patients (80.1%) had good and 7 patients (18.9%) had excellent results. Three patients required revision surgery.

Minimal nerve root retraction during full-endoscopic spine surgery is safe and effective for the treatment of the impending neurologic deficit. They could achieve a thorough decompression of the affected nerve root with acceptable clinical outcome and minimal postoperative morbidity 3).


1)

Nagayama R, Nakamura H, Yamano Y, Yamamoto T, Minato Y, Seki M, Konishi S. An experimental study of the effects of nerve root retraction on the posterior ramus. Spine (Phila Pa 1976). 2000 Feb 15;25(4):418-24. doi: 10.1097/00007632-200002150-00005. PMID: 10707385.
2)

Feltes C, Fountas K, Davydov R, Dimopoulos V, Robinson JS Jr. Effects of nerve root retraction in lumbar discectomy. Neurosurg Focus. 2002 Aug 15;13(2):E6. doi: 10.3171/foc.2002.13.2.7. PMID: 15916403.
3)

Kim HS, Raorane HD, Choi I, Wu PH, Yang KH, Yi YJ, Jang IT. Full-Endoscopic Lumbar Decompression with Minimal Nerve Root Retraction for Impending Neurologic Deficit in Degenerative Lumbar Spine Diseases. J Neurol Surg A Cent Eur Neurosurg. 2021 Jul 8. doi: 10.1055/s-0041-1725955. Epub ahead of print. PMID: 34237776.
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