Stephan Duetzmann

Combination of Intraoperative Magnetic Resonance Imaging and Intraoperative Fluorescence to Enhance the Resection of Contrast Enhancing Gliomas.

BACKGROUND Evidence suggests that extent of resection (EOR) is a prognostic factor for patients harboring gliomas. Recent studies have displayed the importance of intraoperative magnetic resonance imaging (iMRI) with 5-aminolevulinic acid (5-ALA) fluorescence-guidance in order to maximize EOR. OBJECTIVE To compare iMRI and 5-ALA fluorescence-guidance and the impact on patient survival. METHODS Thirty-two patients with contrast-enhancing gliomas undergoing intended gross total resection (GTR) were included in a prospective study. Surgeries were started under white-light conditions. When GTR was thought to be achieved, an iMRI scan was performed and a blue light turned on to search for unintentionally remaining tumor tissue. iMRI findings were compared with intraoperative fluorescence findings. Histological examination of tumor bulk and any additionally resected tissue was performed. All patients underwent early postoperative high-field MRI to determine EOR. RESULTS In 13 patients (40.6%), iMRI and fluorescence unequivocally did not show residual tumor intraoperatively. In 19 patients (59.4%), resection was continued due to iMRI or fluorescence findings. In 9 of these (47.4%), iMRI and fluorescence findings were inconsistent regarding residual tumor. GTR according to postoperative MRI was achieved in all but 1 patient. Histological examination ruled out false positive findings in all additionally resected specimens. Sensitivity and specificity to detect residual tumor tissue were 75% and 100%, respectively, for iMRI and 70% and 100% for 5-ALA fluorescence. CONCLUSION Use of iMRI as well as fluorescence-guidance are appropriate methods to improve the extent of resection in surgery of contrast-enhancing gliomas. Best results can be achieved by complementary use of both modalities.

Oblique Positioning of the Stereotactic Frame for Biopsies of Cerebellar and Brainstem Lesions.

BACKGROUND Frame-based stereotactic biopsy has proven to be a safe procedure with a high diagnostic yield for patients. Different supratentorial localizations can easily be accessed by standardized stereotactic approaches. Cerebellar and brainstem lesions, however, are not easy to reach because the positioning of the frame pins often makes it impossible to address the entry point properly. METHODS By oblique positioning of the frame, cerebellar and brainstem lesions also can easily be accessed to take tissue samples. CONCLUSION Modification of the standardized positioning of the frame allows for safe and straightforward stereotactic access even to cerebellar and brainstem lesions.

Does a medial retraction blade transmit direct pressure to pharyngeal/esophageal wall during anterior cervical surgery?

Study Design. A prospective study of 25 patients who underwent anterior cervical surgery. Objective. To assess retraction pressure and the exposure of pharyngeal/esophageal (P/E) wall to the medial retractor blade to clarify whether medial retraction causes direct pressure transmission to the P/E wall. Summary of Background Data. Retraction pressure on P/E walls has been used to explain the relation between the retraction pressure and dysphagia or the efficacies of new retractor blades. However, it is doubtful whether the measured pressure represent real retraction pressure on the P/E wall because exposure of the P/E in the surgical field could be reduced by the shielding effect of thyroid cartilage. Methods. Epi- and endoesophageal pressures were serially measured using online pressure transducers 15 minutes before retraction, immediately after retraction, and 30 minutes after retraction. To measure the extent of P/E wall exposure to pressure transducer, we used posterior border of thyroid cartilage as a landmark. Intraoperative radiograph was used to mark the position of the posterior border of thyroid cartilage. We checked out the marked location on retractors by measuring the distance from distal retractor tip. Results. The mean epiesophageal pressure significantly increased after retraction (0 mmHg: 88.7 ± 19.6 mmHg: 81.9 ± 15.3 mmHg). The mean endoesophageal pressure minimally changed after retraction (9.0 ± 6.6 mmHg: 15.7 ± 13.8 mmHg: 17.0 ± 14.3 mmHg). The mean location of the posterior border of thyroid cartilage was 7.3 ± 3.5 mm on the retractor blade from the tip, which means epiesophageal pressure was measured against the posterior border of thyroid cartilage, not against the P/E wall. Conclusion. We suggest that a medial retraction blade does not transmit direct pressure on P/E wall due to minimal wall exposure and intervening thyroid cartilage. Our result should be considered when measuring retraction pressure during anterior cervical surgery or designing novel retractor systems. Level of Evidence: 2

A Single-Center Prospective Observational Study of Ultrasonography for 6 Months after Surgical Decompression of the Median Nerve at the Carpal Tunnel.

Objective To determine the natural history of the morphology of the median nerve after carpal tunnel decompression. Methods Between October and December 2014, patients with suspected carpal tunnel were prospectively enrolled and underwent pre‐ and postoperative (3 and 6 months) high‐definition ultrasonography, electrophysiology, and clinical testing. Results A total of 81 patients were enrolled in the study; 75 (93%) could be reached for the 6‐month follow‐up, and 100% were clinically better at the 6‐month follow‐up. The mean cross‐sectional area decreased from 14.3 ± 4.4 mm2to 9.6 ± 2.3 mm2(mean ± standard deviation [SD]). The mean distal motor latency decreased from 6.5 ± 2.2 msec to 4.4 ± 0.8 msec (mean ± SD). Distal motor latency improved statistically significantly after surgical decompression as well, but sooner. Conclusion We present the second largest series of patients with sonographic follow‐up after surgical decompression of the carpal tunnel.

Cross-sectional area of the ulnar nerve after decompression at the cubital tunnel

A total of 48 patients undergoing surgical decompression of the ulnar nerve at the cubital tunnel between February 2010 and May 2013 were retrospectively studied to determine changes in the cross-sectional area of the nerve by the technique of neurosonography. The mean follow-up was 46 months. Post-operative follow-up examination of the cross-sectional area of the ulnar nerve showed a slight reduction in the mean value from 13.8 mm2 (pre-operative) to 12.9 mm2 (post-operative). Of the 48 patients, 36 showed a reduction in the cross-sectional area. No correlation was detected between the clinical and sonographic outcomes. Ultrasound seems to be of limited value in the post-operative assessment of patients with entrapment neuropathy of the ulnar nerve. Level of Evidence: IV

Sacral Peak Pressure in Healthy Volunteers and Patients With Spinal Cord Injury: With and Without Liquid-Based Pad.

BackgroundThe prevalence of sacral pressure ulcers in patients with spinal cord injuries is high. The sacral area is vulnerable to compressive pressure because of immobility and because the sacrum and posterior superior iliac prominence lie closely under the skin with no muscle layer in between. ObjectiveThe aim of this study was to assess peak sacral pressure before and after use of PURAP, a liquid-based pad that covers only the sacral area and can be applied on any bed surface. MethodsHealthy volunteers (n = 12) and patients with spinal cord injuries (n = 10) took part; the patients had undergone spine surgery within 7 days before data collection. Participants were in bed, pretest pressure maps were generated, PURAP was placed for 15 minutes, and then posttest pressure maps were generated. Peak pressure was obtained every second and averaged over the entire period. Patients rated whether their comfort had improved when PURAP was in use. ResultsFor healthy volunteers, mean pretest peak sacral pressure was 74.7 (SD = 16.2) mmHg; the posttest mean was 49.1 (SD = 7.5) mmHg (p < .001, Wilcoxon signed-rank test). For patients with spinal cord injuries, mean pretest peak sacral pressure was 105.7 (SD = 22.4) mmHg; the posttest mean was 81.4 (SD = 18.3) mmHg (p < .001, Wilcoxon signed-rank test). The pad reduced the peak sacral pressure in the patient group by 23% (range = 11%–42%) and in the volunteers by 32% (range = 19%–46%). Overall, 70% of the patients reported increased comfort with PURAP. DiscussionPeak sacral pressure was reduced when PURAP was used. It covers only the sacral area but could help many patients with spinal cord injury because the prevalence of sacral pressure ulcers is high in this group. PURAP may be economically advantageous in countries and hospitals with limited financial resources needed for more expensive mattresses and cushions.

Cross-sectional Area of the Median Nerve Before Revision Carpal Tunnel Release—A Cross-sectional Study

BACKGROUND High-resolution ultrasound can be used for diagnosis of carpal tunnel syndrome with an equal accuracy to electrodiagnostic studies. Up to date there has been no investigation published that examined the median nerve in a large patient cohort with recurrent or persistent symptoms. Reference and cutoff values are lacking. OBJECTIVE To provide reference values for detection of ongoing or recurrent compression in patients with recurring or persisting symptoms in carpal tunnel syndrome. METHODS One hundred and sixteen patients undergoing revision decompression of the median nerve at the carpal tunnel between January 2010 and October 2015 were studied retrospectively to determine the cross-sectional area of the median nerve at the wrist by the technique of neurosonography. RESULTS In cases of insufficient primary release, the mean cross-sectional area was 20.0 mm2 preop. In cases of scar or synovitis, the mean cross-sectional area was 17.0 mm2 (significantly less than in cases of insufficient primary release, P = .008). Compared to successfully operated patients with de novo carpal tunnel syndrome (n = 74), a cutoff value of 14.5 mm2 yielded a sensitivity of 78% and a specificity of 97% to diagnose ongoing or recurrent compression in case of a typical clinical presentation of ongoing or recurrent symptoms (tested via comparison of patients who are symptom free vs patients with symptoms). CONCLUSION For the first time, we provide reference values in patients with recurring or persisting symptoms in carpal tunnel syndrome based on a large patient population. Ultrasound can aid in the evaluation of patients with entrapment neuropathy of the median nerve and recurring or persisting symptoms.

Ex vivo 1H MR spectroscopy and histology after experimental chronic spinal cord compression

BACKGROUND Proton magnetic resonance imaging (MRS) is used increasingly to image the spinal cord in compressive cervical myelopathy (CSM). However, detailed analyses of the underlying histomorphological changes leading to MRS alterations are still lacking. The aim of our study was to correlate neuroimaging and neuropathologic alterations in a rabbit myelopathy model. METHODS Chronic spinal cord compression was induced in a rabbit model (n=16) allowing for a gradual 270° compression of the spinal cord. Spinal cord compression core areas were divided into two samples for (A) 1H MRS and (B) histopathological analyses. Postoperatively the animals underwent a neurological examination twice a day and outcome was categorized in pattern of injury and amount of recovery. RESULTS Three groups were observed and categorized: (I) animals with severe deficits and no or minimal recovery; (II) animals with severe deficits and complete or almost complete recovery; (III) animals with mild to moderate deficits and a complete recovery. Significant differences in the lesioned spinal cords between the different recovery groups were found for N-acetyl-aspartate and choline. NAA/Cr was detected significantly (P<0.001, ANOVA) less in the group that did show permanent neurological deficits. To the contrary, choline was detected significantly (P<0.001, ANOVA) more in the group that did show permanent neurological deficits. Histologically the first group showed more apoptosis and necrosis than the second and third group. CONCLUSIONS MR spectroscopy (MRS) may be helpful for clinicians in improving the prognostic accuracy in cervical myelopathies since this method nicely reflects the extent and severity of spinal cord damage.

Clavicle pain and reduction of incisional and fascial pain after posterior cervical surgery.

OBJECT Incisional pain after posterior cervical spine surgery can be severe and very unpleasant to the patient. Ongoing incisional pain is one of the key disadvantages of posterior over anterior surgical approaches to the cervical spine. It prolongs hospital stays and delays return to work. In this study, the hypothesized that incisional pain in the immediate postoperative period is caused partially by tension on the skin as well as on the deep cervical fascia and the fascia overlying the trapezius, which are usually sewn together during closure. Reduction of this tension through retraction of the shoulders should therefore reduce pain as well as the amount of pain medication used in the early postoperative period. METHODS In this prospective randomized controlled study, 30 patients who had undergone posterior cervical spine surgery were randomized into 2 groups who either wore or did not wear a clavicle brace to retract the shoulders. Patients in the brace group began wearing the brace on postoperative day (POD) 4 and wore it continuously throughout the 30-day study period. Outcome was assessed by two measures: 1) the daily level of self reported pain according to the visual analog scale (VAS) and 2) the number of pain pills taken during the 30-day postoperative period. RESULTS Wearing a clavicle brace in the immediate postoperative period significantly reduced incisional pain and the amount of pain medication that patients took. Beginning on POD 4 and continuing until day POD 13, the mean daily VAS score for pain was significantly lower in the brace group than in the control group. Furthermore, patients who wore the clavicle brace took less pain medication from POD 4 to POD 12. At this point the difference lost significance until the end of the study period. Four patients were randomized but did not tolerate wearing the brace. CONCLUSIONS Patients who tolerated wearing the clavicle brace after posterior cervical spine surgery had reduced pain and used less pain medication.