ZAHRA NASR - Academia.edu (original) (raw)

Papers by ZAHRA NASR

Research paper thumbnail of Neuromotor control associates with muscle weakness observed with McArdle sign of multiple sclerosis

Annals of Clinical and Translational Neurology, 2022

Multiple Sclerosis (MS) is often accompanied by myelopathy, which may be associated with progress... more Multiple Sclerosis (MS) is often accompanied by myelopathy, which may be associated with progressive worsening. A specific finding of MS‐associated myelopathy is McArdle sign, wherein neck flexion is associated with prominent increased limb weakness relative to that detected with neck extension. In this study, we characterized neuromotor control properties of finger extensors in association with the McArdle sign.

Research paper thumbnail of Biomechanical muscle stiffness measures of extensor digitorum explain potential mechanism of McArdle sign

Clinical Biomechanics, 2021

Background: McArdle sign is a phenomenon of impaired gait and muscle weakness that occurs with ne... more Background: McArdle sign is a phenomenon of impaired gait and muscle weakness that occurs with neck flexion, immediately reversible with neck extension. A recent report measured the specificity of this sign for multiple sclerosis by measuring differences in peak torque of the extensor digitorum between neck extension and flexion. Methods: This substudy included 73 participants (29 multiple sclerosis, 20 non-multiple sclerosis myelopathies, 5 peripheral nerve disorders, and 19 healthy controls). The effect of neck position was assessed on muscle stiffness and neuromechanical error of the extensor digitorum. Findings: Patients with multiple sclerosis had greater neuromechanical error (sum of squared error of prediction) compared to controls (P=0.023) and non-multiple sclerosis myelopathies (P=0.003). Neuromechanical error also provided improved sensitivity/specificity of McArdle sign. Peak torque, muscle stiffness, and neuromechanical error could distinguish multiple sclerosis from other myelopathies with 80% specificity and 97% sensitivity (AUC=0.95).

Research paper thumbnail of Long term Mortality in Neuromyelitis Optica Spectrum Disorder (P6.414)

Neurology, 2018

Objective: To assess the long term outcomes of patients with neuromyelitis optica spectrum disord... more Objective: To assess the long term outcomes of patients with neuromyelitis optica spectrum disorder (NMOSD). Background: Pre-aquaporin-4 IgG studies have reported a five year survival rate of 68% and median survival of 17.5 years (y). More contemporary studies report mortality rate of approximately 25% in those with disease duration of less than 10 years. African American race has been associated with greater mortality. Design/Methods: Retrospective study of patients evaluated at Mayo Clinic with onset prior to October, 2006. Results: 143 patients were identified; 22 (15%) were deceased, 4 men and 18 women; the median age of death was 58.5y (41–94). A comparison of deceased versus living patients in this study revealed the following: median follow up was 3y (range 0–8) versus 6y (0–21); median disease duration was 11y (3–28) versus 16y (9–49); median age of onset was 43y (30–83) versus 39y (21–71); median number of relapses was 6 (2–22) versus 5 (5–19); median last known Expanded Di...

Research paper thumbnail of McArdle’s sign: a specific sign of multiple sclerosis (P1.087)

Neurology, 2018

Objective: We quantified McArdle’s Sign (McS) in finger extensors using a torque measuring device... more Objective: We quantified McArdle’s Sign (McS) in finger extensors using a torque measuring device and assessed its specificity for MS. Background: McS is rapidly reversible motor weakness induced by head flexion in patients with multiple sclerosis (MS). Design/Methods: We enrolled 25 healthy controls (HC) and 76 patients with detectable finger extensor weakness, 52 with MS, 24 with other myelopathies (OM), 5 with peripheral nerve lesions (PNL); patients were not selected for having McS. We evaluated McS blinded to diagnosis by measuring changes in finger extensor strength in successive trials of neck extension and flexion, first clinically (rated 0 to 3) and then with a torque measurement cell. Results: The median clinical McS was 1 (range 0–3) in MS patients, 0 (0–2) in OM, 0 (0–1) in HC and 0 in all PNL (p versus HC and MS versus OM. A 10% drop in strength with flexion was 100% specific and 63% sensitive for MS compared to OM and an 8% drop 100% specific and 65% sensitive for MS c...

Research paper thumbnail of McArdle Sign: A Specific Sign of Multiple Sclerosis

Mayo Clinic Proceedings, 2019

Objective: To measure McArdle sign (rapidly reversible weakness induced by neck flexion) both qua... more Objective: To measure McArdle sign (rapidly reversible weakness induced by neck flexion) both qualitatively and quantitatively and to evaluate its specificity and clinical utility for diagnosis of multiple sclerosis (MS). Patients and Methods: In this prospective study, McArdle sign was evaluated by a technician blinded to diagnosis by measuring changes in finger extensor strength in successive trials of neck extension and flexion, first clinically and then with a torque measurement device. We studied 25 healthy controls and 81 patients with finger extensor weakness. Patients were not selected for having McArdle sign. Fifty-two patients had MS, 24 had other myelopathies, and 5 had peripheral nerve lesions accounting for their weakness. The study was conducted between February 1, 2016, and June 30, 2017. Results: The median clinical McArdle sign and the 2 quantitative measures of neck flexioneinduced strength reduction were greater in patients with MS than in the other groups (P<.001). Baseline strength did not confound the difference. The area under the receiver operating characteristic curve was 0.84 (95% CI, 0.75-0.93) comparing patients with MS vs healthy controls and 0.84 (95% CI, 0.75-0.93) comparing MS vs patients with other myelopathies. The 2 quantitative and 1 clinical measurement of McArdle sign by the technician who performed the quantitative testing were correlated (r¼.57 and r¼.58; P<.001), and in turn, the technician's and unblinded referring physician's clinical assessments were correlated (r¼.58; P<.001). McArdle sign was evident in some patients who had minor disability and who were in early phases of MS. Conclusion: McArdle sign, when defined as greater than 10% neck flexioneinduced reduction in strength, is entirely specific and 65% sensitive for a diagnosis of MS when compared with other conditions that mimic MS-associated myelopathy. It may facilitate diagnosis in certain clinical situations. Trial Registration: clinicaltrials.gov Identifier: NCT03122873.

Research paper thumbnail of Using virtual reality in the classroom: preservice teachers’ perceptions of its use as a teaching and learning tool

Educational Media International, 2019

Virtual reality (VR) platforms act as a potentially transformative tool in learning and teaching.... more Virtual reality (VR) platforms act as a potentially transformative tool in learning and teaching. The aim of this study was to examine pre-service teachers' (PST) perceptions about VR, inclusive of their beliefs about its capacity to be used as a teaching and learning tool. A case-study, conducted at an urban university in Australia involved a sample of n = 41. Participants' positive perceptions of VR in their teaching relate to its potential to engage learners, the immersive potential of the platform and the scope of VR to offer students experiences they might otherwise not have with other learning tools. Concerns expressed by PSTs include their relatively low selfefficacy to use VR in their teaching, monitoring-related matters, financial cost and implementing the technology in a safe and supportive way. There was a significant difference in PSTs' amount of self-efficacy to teach using VR when compared to their overall confidence to use digital technologies. PSTs typically had greater awareness of the immersive and engagement potential of VR and less awareness about its potential to foster and promote collaborative learning. This paper contributes to an emerging discourse regarding the possible applications of VR in educational environments and particularly in relation teacher-educator contexts.

Research paper thumbnail of Neuromotor control associates with muscle weakness observed with McArdle sign of multiple sclerosis

Annals of Clinical and Translational Neurology, 2022

Multiple Sclerosis (MS) is often accompanied by myelopathy, which may be associated with progress... more Multiple Sclerosis (MS) is often accompanied by myelopathy, which may be associated with progressive worsening. A specific finding of MS‐associated myelopathy is McArdle sign, wherein neck flexion is associated with prominent increased limb weakness relative to that detected with neck extension. In this study, we characterized neuromotor control properties of finger extensors in association with the McArdle sign.

Research paper thumbnail of Biomechanical muscle stiffness measures of extensor digitorum explain potential mechanism of McArdle sign

Clinical Biomechanics, 2021

Background: McArdle sign is a phenomenon of impaired gait and muscle weakness that occurs with ne... more Background: McArdle sign is a phenomenon of impaired gait and muscle weakness that occurs with neck flexion, immediately reversible with neck extension. A recent report measured the specificity of this sign for multiple sclerosis by measuring differences in peak torque of the extensor digitorum between neck extension and flexion. Methods: This substudy included 73 participants (29 multiple sclerosis, 20 non-multiple sclerosis myelopathies, 5 peripheral nerve disorders, and 19 healthy controls). The effect of neck position was assessed on muscle stiffness and neuromechanical error of the extensor digitorum. Findings: Patients with multiple sclerosis had greater neuromechanical error (sum of squared error of prediction) compared to controls (P=0.023) and non-multiple sclerosis myelopathies (P=0.003). Neuromechanical error also provided improved sensitivity/specificity of McArdle sign. Peak torque, muscle stiffness, and neuromechanical error could distinguish multiple sclerosis from other myelopathies with 80% specificity and 97% sensitivity (AUC=0.95).

Research paper thumbnail of Long term Mortality in Neuromyelitis Optica Spectrum Disorder (P6.414)

Neurology, 2018

Objective: To assess the long term outcomes of patients with neuromyelitis optica spectrum disord... more Objective: To assess the long term outcomes of patients with neuromyelitis optica spectrum disorder (NMOSD). Background: Pre-aquaporin-4 IgG studies have reported a five year survival rate of 68% and median survival of 17.5 years (y). More contemporary studies report mortality rate of approximately 25% in those with disease duration of less than 10 years. African American race has been associated with greater mortality. Design/Methods: Retrospective study of patients evaluated at Mayo Clinic with onset prior to October, 2006. Results: 143 patients were identified; 22 (15%) were deceased, 4 men and 18 women; the median age of death was 58.5y (41–94). A comparison of deceased versus living patients in this study revealed the following: median follow up was 3y (range 0–8) versus 6y (0–21); median disease duration was 11y (3–28) versus 16y (9–49); median age of onset was 43y (30–83) versus 39y (21–71); median number of relapses was 6 (2–22) versus 5 (5–19); median last known Expanded Di...

Research paper thumbnail of McArdle’s sign: a specific sign of multiple sclerosis (P1.087)

Neurology, 2018

Objective: We quantified McArdle’s Sign (McS) in finger extensors using a torque measuring device... more Objective: We quantified McArdle’s Sign (McS) in finger extensors using a torque measuring device and assessed its specificity for MS. Background: McS is rapidly reversible motor weakness induced by head flexion in patients with multiple sclerosis (MS). Design/Methods: We enrolled 25 healthy controls (HC) and 76 patients with detectable finger extensor weakness, 52 with MS, 24 with other myelopathies (OM), 5 with peripheral nerve lesions (PNL); patients were not selected for having McS. We evaluated McS blinded to diagnosis by measuring changes in finger extensor strength in successive trials of neck extension and flexion, first clinically (rated 0 to 3) and then with a torque measurement cell. Results: The median clinical McS was 1 (range 0–3) in MS patients, 0 (0–2) in OM, 0 (0–1) in HC and 0 in all PNL (p versus HC and MS versus OM. A 10% drop in strength with flexion was 100% specific and 63% sensitive for MS compared to OM and an 8% drop 100% specific and 65% sensitive for MS c...

Research paper thumbnail of McArdle Sign: A Specific Sign of Multiple Sclerosis

Mayo Clinic Proceedings, 2019

Objective: To measure McArdle sign (rapidly reversible weakness induced by neck flexion) both qua... more Objective: To measure McArdle sign (rapidly reversible weakness induced by neck flexion) both qualitatively and quantitatively and to evaluate its specificity and clinical utility for diagnosis of multiple sclerosis (MS). Patients and Methods: In this prospective study, McArdle sign was evaluated by a technician blinded to diagnosis by measuring changes in finger extensor strength in successive trials of neck extension and flexion, first clinically and then with a torque measurement device. We studied 25 healthy controls and 81 patients with finger extensor weakness. Patients were not selected for having McArdle sign. Fifty-two patients had MS, 24 had other myelopathies, and 5 had peripheral nerve lesions accounting for their weakness. The study was conducted between February 1, 2016, and June 30, 2017. Results: The median clinical McArdle sign and the 2 quantitative measures of neck flexioneinduced strength reduction were greater in patients with MS than in the other groups (P<.001). Baseline strength did not confound the difference. The area under the receiver operating characteristic curve was 0.84 (95% CI, 0.75-0.93) comparing patients with MS vs healthy controls and 0.84 (95% CI, 0.75-0.93) comparing MS vs patients with other myelopathies. The 2 quantitative and 1 clinical measurement of McArdle sign by the technician who performed the quantitative testing were correlated (r¼.57 and r¼.58; P<.001), and in turn, the technician's and unblinded referring physician's clinical assessments were correlated (r¼.58; P<.001). McArdle sign was evident in some patients who had minor disability and who were in early phases of MS. Conclusion: McArdle sign, when defined as greater than 10% neck flexioneinduced reduction in strength, is entirely specific and 65% sensitive for a diagnosis of MS when compared with other conditions that mimic MS-associated myelopathy. It may facilitate diagnosis in certain clinical situations. Trial Registration: clinicaltrials.gov Identifier: NCT03122873.

Research paper thumbnail of Using virtual reality in the classroom: preservice teachers’ perceptions of its use as a teaching and learning tool

Educational Media International, 2019

Virtual reality (VR) platforms act as a potentially transformative tool in learning and teaching.... more Virtual reality (VR) platforms act as a potentially transformative tool in learning and teaching. The aim of this study was to examine pre-service teachers' (PST) perceptions about VR, inclusive of their beliefs about its capacity to be used as a teaching and learning tool. A case-study, conducted at an urban university in Australia involved a sample of n = 41. Participants' positive perceptions of VR in their teaching relate to its potential to engage learners, the immersive potential of the platform and the scope of VR to offer students experiences they might otherwise not have with other learning tools. Concerns expressed by PSTs include their relatively low selfefficacy to use VR in their teaching, monitoring-related matters, financial cost and implementing the technology in a safe and supportive way. There was a significant difference in PSTs' amount of self-efficacy to teach using VR when compared to their overall confidence to use digital technologies. PSTs typically had greater awareness of the immersive and engagement potential of VR and less awareness about its potential to foster and promote collaborative learning. This paper contributes to an emerging discourse regarding the possible applications of VR in educational environments and particularly in relation teacher-educator contexts.