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Daipayan Guha, Benjamin Davidson, Mustafa Nadi, Naif M. Alotaibi, Michael G. Fehlings, Fred Gentili, Taufik A. Valiante, Charles H. Tator, Michael Tymianski, Abhijit Guha and Gelareh Zadeh

OBJECTIVE

A surgical series of 201 benign and malignant peripheral nerve sheath tumors (PNSTs) was assessed to characterize the anatomical and clinical presentation of tumors and identify predictors of neurological outcome, recurrence, and extent of resection.

METHODS

All surgically treated PNSTs from the Division of Neurosurgery at Toronto Western Hospital from 1993 to 2010 were reviewed retrospectively. Data were collected on patient demographics, clinical presentation, surgical technique, extent of resection, postoperative neurological outcomes, and recurrence.

RESULTS

One hundred seventy-five patients with 201 tumors had adequate follow-up for analysis. There were 182 benign and 19 malignant PNSTs. Of the benign lesions, 133 were schwannomas, 21 of which were associated with a diagnosis of schwannomatosis. There were 49 neurofibromas, and 26 were associated with neurofibromatosis Type 1 (NF1). Patients presenting with schwannomas were significantly older than those with neurofibromas. Schwannomas were more readily resected than neurofibromas, with the extent of resection of the former influenced by tumor location. Patients with benign PNSTs typically presented with a painful mass and less frequently with motor deficits. The likelihood of worsened postoperative motor function was decreased in patients with fully resected tumors or preoperative deficits. Recurrence of schwannomas and neurofibromas were seen more frequently in patients diagnosed with NF3 and NF1, respectively. Subtotal resection was associated with the increased recurrence of all benign lesions.

CONCLUSIONS

Outcomes following resection of benign PNSTs depend on tumor histopathology, tumor location, and genetic predisposition syndrome. Gross-total resection should be attempted for benign lesions where possible. The management of malignant PNSTs remains challenging, requiring a multimodal approach.

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Benjamin Davidson, Lior M. Elkaim, Nir Lipsman and George M. Ibrahim

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Alexandre Boutet, Dave Gwun, Robert Gramer, Manish Ranjan, Gavin J. B. Elias, David Tilden, Yuexi Huang, Stanley Xiangyu Li, Benjamin Davidson, Hua Lu, Pascal Tyrrell, Ryan M. Jones, Alfonso Fasano, Kullervo Hynynen, Walter Kucharczyk, Michael L. Schwartz and Andres M. Lozano

OBJECTIVE

Transcranial MR-guided focused ultrasound (MRgFUS) is a minimally invasive treatment for movement disorders. Considerable interpatient variability in skull transmission efficiency exists with the current clinical devices, which is thought to be dependent on each patient’s specific skull morphology. Lower skull density ratio (SDR) values are thought to impede acoustic energy transmission across the skull, attenuating or preventing the therapeutic benefits of MRgFUS. Patients with SDR values below 0.4 have traditionally been deemed poor candidates for MRgFUS. Although considerable anecdotal evidence has suggested that SDR is a reliable determinant of procedural and clinical success, relationships between SDR and clinical outcomes have yet to be formally investigated. Moreover, as transcranial MRgFUS is becoming an increasingly widespread procedure, knowledge of SDR distribution in the general population may enable improved preoperative counseling and preparedness.

METHODS

A total of 98 patients who underwent MRgFUS thalamotomy at the authors’ institutions between 2012 and 2018 were analyzed (cohort 1). The authors retrospectively assessed the relationships between SDR and various clinical outcomes, including tremor improvement and adverse effects, as well as procedural factors such as sonication parameters. An SDR was also prospectively obtained in 163 random emergency department patients who required a head CT scan for various clinical indications (cohort 2). Patients’ age and sex were used to explore relationships with SDR.

RESULTS

In the MRgFUS treatment group, 17 patients with a thalamotomy lesion had an SDR below 0.4. Patients with lower SDRs required more sonication energy; however, their low SDR did not influence their clinical outcomes. In the emergency department patient group, about one-third of the patients had a low SDR (< 0.4). SDR did not correlate with age or sex.

CONCLUSIONS

Although lower SDR values correlated with higher energy requirements during MRgFUS thalamotomy, within the range of this study population, the SDR did not appreciably impact or provide the ability to predict the resulting clinical outcomes. Sampling of the general population suggests that age and sex have no relationship with SDR. Other variables, such as local variances in bone density, should also be carefully reviewed to build a comprehensive appraisal of a patient’s suitability for MRgFUS treatment.

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Benjamin Davidson, Nathan Schoen, Shaina Sedighim, Renée Haldenby, Blythe Dalziel, Sara Breitbart, Darcy Fehlings, Golda Milo-Manson, Unni G. Narayanan, James M. Drake and George M. Ibrahim

OBJECTIVE

Cerebral palsy (CP) is the most common childhood physical disability. Historically, children with hypertonia who are nonambulatory (Gross Motor Function Classification System [GMFCS] level IV or V) were considered candidates for intrathecal baclofen (ITB) therapy to facilitate care and mitigate discomfort. Selective dorsal rhizotomy (SDR) was often reserved for ambulant children to improve gait. Recently, case series have suggested SDR as an alternative to ITB in selected children functioning at GMFCS level IV/V. The objective for this study was to systematically review the evidence for ITB and SDR in GMFCS level IV or V children.

METHODS

Medline, Embase, Web of Science, and Cochrane databases were systematically searched. Articles were screened using the following inclusion criteria: 1) peer-reviewed articles reporting outcomes after SDR or ITB; 2) outcomes reported using a quantifiable scale or standardized outcome measure; 3) patients were < 19 years old at the time of operation; 4) patients had a diagnosis of CP; 5) patients were GMFCS level IV/V or results were reported based on GMFCS status and included some GMFCS level IV/V patients; 6) article and/or abstract in English; and 7) primary indication for surgery was hypertonia. Included studies were assessed with the Risk of Bias in Non-Randomized Studies - of Interventions (ROBINS-I) tool.

RESULTS

Twenty-seven studies met inclusion criteria. The most commonly reported outcomes were spasticity (on the Mean Ashworth Scale) and gross motor function (using the Gross Motor Function Measure), although other outcomes including frequency of orthopedic procedures and complications were also reported. There is evidence from case series that suggests that both ITB and SDR can lower spasticity and improve gross motor function in this nonambulatory population. Complication rates are decidedly higher after ITB due in part to the ongoing risk of device-related complications. The heterogeneity among study design, patient selection, outcome selection, and follow-up periods was extremely high, preventing meta-analysis. There are no comparative studies, and meaningful health-related quality of life outcomes such as care and comfort are lacking. This review is limited by the high risk of bias among included studies. Studies of SDR or ITB that did not clearly describe patients as being GMFCS level IV/V or nonambulatory were excluded.

CONCLUSIONS

There is a lack of evidence comparing the outcomes of ITB and SDR in the nonambulatory CP population. This could be overcome with standardized prospective studies using more robust methodology and relevant outcome measures.