Selective dorsal rhizotomy: short-term results and early experiences with a newly established surgical treatment in Slovenia.

BACKGROUND: Spasticity is characterised by an atypical increase of muscle tone, affecting normal movements and interfering with the patient quality of life. The medicines may limit the effects of the disease and selective dorsal rhizotomy (SDR) can be used for selected cases or cases refractory to medicine. We present the surgical technique and the short-term results of this newly established surgical treatment in Slovenia. METHODS: A retrospective analysis was performed of all patients that underwent the SDR from 2017 to 2019. The median follow-up was of 10 months. The following data have been collected: aetiology of spasticity, age at SDR, number of sectioned lumbar rootlets L1-S2, intraoperative disappearance of the H-reflex and intraoperative preservation of the bulbocavernosus reflex. The motor functions of all children have been classified by the Gross Motor Function Classification System (GMFCS) and Gross Motor Function Measure (GMFM-88). Twelve children underwent SDR, the median age at surgery was 9.6 years (min 3.9-max 16 years). RESULTS: A mean of 57.8% of dorsal rootlets L2-S1 have been cut, while at level L1 50% of the dorsal roots have been routinely sectioned. The median amount of S2 rootlets cut was 14.3%. Postoperatively, we observed a sudden decrease in muscle tone. In all patients, there was an improvement of the muscle tone and of the gait pattern. The GMFM improved from 187.8 to 208.3 after a follow-up of 6 months. CONCLUSIONS: There was no complication in terms of wound healing, cerebrospinal fluid fistula of neurological dysfunctions. Despite the relatively short follow-up, our early results confirm the efficacy of the SDR.

Continuous Dynamic Mapping of the Corticospinal Tract in Motor Eloquent Tumor Surgery: Our Experience and Evaluation of the Method.

OBJECTIVE: The aim of this article is to present our experience with continuous dynamic mapping (CDM) of the corticospinal tract (CST) when removing tumors in motor eloquent regions. METHODS: We studied 44 patients with a brain tumor adjacent to the CST where CDM was used. The mapping probe was integrated at the tip of the suction device. Thresholds for eliciting MEPs were recorded. In all patients, along with CDM, MEPs to direct cortical stimulation were also monitored throughout the operation. Motor function was assessed preoperatively, after the procedure and on discharge. RESULTS: In the series, there were 37 patients with gliomas, six with brain metastasis, and one with cavernoma. The threshold to elicit MEPs in CDM was >20 mA in 17 cases, 16-20 mA in six cases, 11-15 mA in six cases, 6-10 mA in nine cases and 2-5 mA in six cases. MEPs to direct cortical stimulation were preserved in all patients. In three cases a new temporary motor deficit was noted. No new permanent motor deficit occurred. Gross total resection was reached in 57% of cases. CONCLUSIONS: From our experience, the combined use of CDM and MEPs to direct cortical stimulation improves the safety of surgery in the proximity of the CST, and at the same time offers the possibility of higher rates of gross total resection.

Selective dorsal rhizotomy in cerebral palsy spasticity - a newly established operative technique in Slovenia: A case report and review of literature.

BACKGROUND: Spasticity affects a large number of children, mainly in the setting of cerebral palsy, however, only a few paediatric neurosurgeons deal with this problem. This is mainly due to the fact that until 1979, when Fasano has published the first series of selective dorsal rhizotomy (SDR), neurosurgeons were able to provide such children only a modest help. The therapy of spasticity has made a great progress since then. Today, peroral drugs, intramuscular and intrathecal medicines are available, that may limit the effects of the disease. In addition, surgical treatment is gaining importance, appearing in the form of deep brain stimulation, peripheral nerve procedures and SDR. All these options offer the affected children good opportunities of improving the quality of life. CASE SUMMARY: A 15-year old boy is presented that was surgically treated for spasticity as a result of cerebral palsy. Laminotomy at L1 level was performed and L1 to S1 nerve roots were isolated and divided in smaller fascicles. Then, the SDR was made. CONCLUSION: We describe a patient report and surgical technique of SDR that was performed in Slovenia for the first time.

The impact on post-operative shoulder function of intraoperative nerve monitoring of cranial nerve XI during modified radical neck dissection.

Intraoperative monitoring of the cranial nerve XI (CN XI) may decrease shoulder disability following modified radical neck dissection. Prospective study was designed comparing results of Constant Shoulder Score (CSS), Shoulder Pain and Disability Index (SPADI) and EMG score of the trapezius muscle (mT) before and after surgery. One side of the neck was monitored during surgery with intraoperative nerve monitor. EMG scores of the mT 6 months postoperatively were statistically better on monitored as compared to the non-monitored side of the neck (p = 0.041), while the differences of the CSS and SPADI were not statistically significant. Patients with better EMG scores of the mT at 6 weeks recuperated better and with smaller decrease of the CSS. Intraoperative monitoring is beneficial at the beginning of the surgeon's learning curve and in the process of familiarizing with anatomical variation of the CN XI.

Electrophysiologic analysis of injury to cranial nerve XI during neck dissection.

BACKGROUND: Despite preservation of the accessory nerve, a considerable number of patients report partial nerve damage after modified radical neck dissection (MRND) and selective neck dissection. METHODS: Accessory nerve branches for the trapezius muscle were stimulated during neck dissection, and the M wave amplitude was measured during distinct surgical phases. RESULTS: The accessory nerve was mapped in 20 patients. The M wave recordings indicated that major nerve damage occurred during dissection at levels IIa and IIb in the most proximal segment of the nerve. The M waves evoked from this nerve segment decreased significantly during surgery (analysis of variance; p = .001). CONCLUSION: The most significant intraoperative injury to the accessory nerve during neck dissection occurs at anatomic nerve levels IIa and IIb. © 2015 Wiley Periodicals, Inc. Head Neck 38: E372-E376, 2016.

Stimulation of Cauda Equina With a Figure-of-Eight Magnetic Coil.

PURPOSE: To record responses in the abductor hallucis muscle after lumbosacral stimulation with a figure-of-eight magnetic coil. To compare magnetic stimulation (MS), electrical stimulation (ES), and the peripheral motor conduction time. METHODS: M and F waves and compound muscle action potentials were recorded after L1 MS, S1 MS, and L1 ES. RESULTS: The compound muscle action potential latency on L1 MS was 26.9 ± 2.6 milliseconds and on L1 ES was 25.6 ± 2.2 milliseconds, and the peripheral motor conduction time was 27.0 ± 2.5 milliseconds (analysis of variance P = 0.0008). The compound muscle action potential amplitude was 12 ± 11% of M-wave on L1 MS, 32 ± 18% on S1 MS, and 31 ± 17% on L1 ES. CONCLUSIONS: Dorsal MS reliably elicits responses in the abductor hallucis muscle. The latency of compound muscle action potentials on L1 MS is comparable to peripheral motor conduction time. A potential drawback of MS may be too weak stimulation at the proximal end of the cauda equina.

Identification of three anatomical patterns of the spinal accessory nerve in the neck by neurophysiological mapping.

BACKGROUND: In spite of preservation of the accessory nerve there is still considerable proportion of patients with partial nerve damage during modified radical neck dissection (MRND). METHODS: The nerve was identified during the surgery and its branches for the trapezius muscle mapped with nerve monitor. RESULTS: The accessory nerve was mapped during 74 hemineck dissections and three patterns were identified. In type 1 nerve exits at the posterior end of the sternocleidomastoid muscle (SCm) and then it enters the level V (66%). In type 2 the nerve for trapezius muscle branches off before entering the SCm (22%). In type 3 the nerve exits at the posterior part of the SCm and it joins to the cervical plexus (12%). The nerve than exits this junction more medially as a single trapezius branch. CONCLUSIONS: The description of three anatomical patterns in level II and V could help preserving the trapezius branch during MRND.

Influence of muscle contraction and intensity of stimulation on the cutaneous silent period.

We evaluated the influence of stimulus intensity (SI) and the amount of voluntary muscle contraction (VMC) on parameters of the cutaneous silent period (CSP). The CSP was measured in 15 healthy subjects at 20%, 40%, and 60% of maximal VMC and after an electric stimulus of 10, 15, and 20 times the sensory threshold. Average EMG amplitudes prior to stimulus and during the CSP increased with the amount of VMC. The CSP duration increased, and suppression index decreased, with increasing SI. The CSP onset and end latencies seemed to shorten and prolong, respectively, with the increasing SI, although this was not statistically significant. Considering the more meaningful temporal parameters of the CSP and the suppression index, it is not necessary to control the VMC, but it is advisable to control the SI.

The relationship between visually evoked cerebral blood flow velocity responses and visual-evoked potentials.

A noninvasive assessment of neurovascular coupling would be of great importance. For this reason, we simultaneously studied graded responses of visually evoked cerebral blood flow (CBF) velocity responses (VEFR) and visual-evoked potentials (VEP) to visual contrasts. The records were made from 30 healthy volunteers aged 38.0 +/- 9.6 years. The stimulus was a black-and-white checkerboard with visual contrasts (VC) of 1%, 10%, and 100%. The VEFR were measured in the posterior cerebral artery using transcranial Doppler, and the VEP were recoded from the scalp from occipital leads. To test the relationship between the VEFR and the VEP, a linear regression analysis was performed. We found that the VEFR at 100% VC were 36% higher than those at 10% VC (P < 0.01). The VEFR at 10% VC were 81% higher than those at 1% VC (P < 0.01). The VEP at 100% VC were 76% higher than those at 10% VC (P < 0.01). The VEP at 10% VC were 184% higher than those at 1% VC (P < 0.01). The linear regression showed a significant, moderate association between the VEP and the VEFR (r = 0.66, P < 0.01). The analysis of the regression slopes (b = 0.48 in older subjects vs. b = 0.58 in younger subjects) between two different age subgroups (P < 0.01) did not show any significant difference (P = 0.035). We concluded that a simultaneous recording of VEFR and VEP to graded visual contrasts could allow an assessment of neurovascular coupling.

Transient paraplegia revealed by intraoperative neurophysiological monitoring: was it caused by the epidural anesthetic or an epidural hematoma?

IMPLICATIONS: Our case report describes the electrophysiological features associated with the development of a spinal epidural hematoma during surgery of the lumbar spine. It stresses the importance of the evaluation of nonsurgical factors, which can potentially affect intraoperative evoked potentials; in this case, epidural local anesthetic or epidural hematoma.