J Neurol DOI 10.1007/s00415-017-8634-5
LETTER TO THE EDITORS
Gait variability predicts a subset of falls in cerebellar gait disorders Cornelia Schlick1 · Atal Rasoul1 · Max Wuehr1 · Julia Gerth1 · Marianne Dieterich1,2 · Thomas Brandt1,3 · Klaus Jahn1,4 · Roman Schniepp1,2
Received: 7 August 2017 / Revised: 25 September 2017 / Accepted: 28 September 2017 © Springer-Verlag GmbH Germany 2017
Dear Sirs, Falling is a major complication in patients with cerebellar gait disorders. The annual fall prevalence in patients with cerebellar dysfunction lies between 65 and 90% [1–3]. Many of these patients suffer from injurious falls and need to seek medical attention [1–3]. Therefore, valid risk estimation measures are of high clinical importance to identify patients prone to falls, and to initiate fall prevention strategies early. One major characteristic in cerebellar gait disorders is a high variability of the spatial and temporal gait parameters [4, 5]. Increased gait variability was found to be associated with falls in patients with hereditary as well as sporadic ataxia [5, 6], and may therefore serve as a predictive measure for the identification of patients at high risk of falling. However, risk factors are most likely specific to certain fall mechanisms. For example, while a sudden trip may be due to an impaired multi-joint coordination during locomotion, the decisive factor for falling over an obstacle could be lack of visuomotor control or attention. We therefore studied the incidence and causes of falls in patients with cerebellar gait disorders to then examine if increased gait variability can predict the occurrence of * Cornelia Schlick [email protected]‑muenchen.de 1
German Center for Vertigo and Balance Disorders, University Hospital Munich, Ludwig-MaximiliansUniversity, Munich, Germany
2
Department of Neurology, University Hospital Munich, Lud wig-Maximilians-University, Munich, Germany
3
Institute of Clinical Neurosciences, University Hospital Munich, Ludwig-Maximilians-University, Munich, Germany
4
Schön Klinik Bad Aibling, Bad Aibling, Germany
different falls, categorized according to their fall mechanism. In a prospective cohort study on fall risk in patients with vertigo and balance disorders (trial number: DRKS00006243), twenty-four patients with cerebellar gait disorders were included (sporadic adult-onset ataxia n = 7, spinocerebellar ataxia type II n = 3, spinocerebellar ataxia type III n = 3, paraneoplastic n = 1, Friedreich’s ataxia n = 10). At baseline, symptom severity was classified using the scale for the assessment and rating of ataxia (SARA) [7]. Gait was assessed on a 6.7 m pressure-sensitive sensor mat (GAITRite, CIR System, Havertown, USA). Patients were asked to walk over the mat in different walking conditions. No walking aids were used during the recordings. The coefficients of variation (CV) of stride time and stride length during preferred walking speed were taken for the analysis. A detailed method description of the gait measurements and data processing can be found in [5]. Falls were recorded using a fall diary and monthly telephone interviews during a 6-month follow-up. Frequency, severity and causes of falls were captured. All fall events were then grouped according to the Hopkins Fall Grading Scale [8] and categorized by their fall mechanism. The association between the most frequent fall categories and gait variability was investigated using logistic regression analysis. The patients were on average 47.4 (± 14.0) years old (8 females). The mean SARA score was 12.2 (± 4.4) points, ranging from 3 to 18 points. Twelve patients used a walking frame, 10 of them outside and two of them inside their home environment. Table 1a displays the 6 months incidence of falls and their severity. Three major fall mechanisms were identified and categorized as: (1) transitions from one body position to another, e.g., from lying to standing, (2) tripping while unperturbed walking and (3) managing stairs (Fig. 1). Among these categories, only falls due to tripping while unperturbed walking
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Vol.:(0123456789)
J Neurol
Table 1 (a) Frequency and severity of falls in 24 patients with various cerebellar ataxias. (b) Association between the three major fall categories and gait variability
(a) Falls within 6 months Near-fall (Hopkins 1) Fall, no or mild injury (Hopkins 2) Fall requiring medical attention (Hopkins 3) Fall requiring hospital admission (Hopkins 4)
Falls, n (%)
Fallersa, n (%)
135 (100) 81/135 (60) 53/135 (39) 1/135 (1) 0/135
20/24 (83) 15/24 (63) 15/24 (63) 1/24 (4) 0/24
Odds ratiob
(b) Falls due to
Change in position Trip while unperturbed walking Managing stairs
Stride time CVc
Stride length CVc
SARA score
1.0 [0.7;1.4] 3.9 [1.2;12.5] 1.0 [0.7;1.4]
1.3 [0.9;1.8] 2.5 [1.1; 6.1] 1.0 [0.8;1.3]
1.1 [0.8;1.4] 2.0 [1.1;4.0] 1.0 [0.8;1.2]
a
Patient reporting at least one fall during 6 months
b c
Adjusted for age and gender
Coefficient of variation
Change in position Trip while unperturbed walking Managing stairs Other Trip over an obstacle Slippery / uneven terrain Loss of strength Trip while handling objects Cause not known / not remembered Poor visibility Trip while using public transportation Hastiness 5
10
15
20
25
Number of falls (total n = 135)
Fig. 1 Number of a total of 135 falls categorized by fall mechanism
The findings of this study give differential information on the relationship between gait variability and the risk of falls, with respect to different fall mechanisms. Gait variability, that is known to be a marker for dynamic stability of the locomotor pattern, is associated with trip-related falls during steady state walking, but not with falls during more complex balance tasks. This finding implies that increased stride time variability is a good measure to quantify locomotor pacemaker control and coordination during walking [6], and that these features are relevant for falls with a tripping mechanism. However, gait variability carries less information about flexibility and adaptability of the locomotor pattern during complex balance tasks that involve shifting weight during turns, body transitions and stair walking. Clinically, the study indicates that gait fluctuation measures alone are not completely sufficient for characterizing dynamic stability and fall risk in patients with cerebellar gait disorders. It is therefore desirable to investigate and include other factors to untangle dynamic stability properties during different fall mechanisms in these patients. Acknowledgements The work was supported by the Federal Ministry for Education and Science (BMBF, IFB01EO1401) of Germany. Compliance with ethical standards
were associated with an increase in stride time CV and stride length CV (Table 1b). Similarly, the total SARA score was predictive of falls due to tripping while unperturbed walking alone (Table 1b). The total SARA score was positively correlated with the gait variability measures (stride time CV: rSpearman = 0.6, p
LETTER TO THE EDITORS
Gait variability predicts a subset of falls in cerebellar gait disorders Cornelia Schlick1 · Atal Rasoul1 · Max Wuehr1 · Julia Gerth1 · Marianne Dieterich1,2 · Thomas Brandt1,3 · Klaus Jahn1,4 · Roman Schniepp1,2
Received: 7 August 2017 / Revised: 25 September 2017 / Accepted: 28 September 2017 © Springer-Verlag GmbH Germany 2017
Dear Sirs, Falling is a major complication in patients with cerebellar gait disorders. The annual fall prevalence in patients with cerebellar dysfunction lies between 65 and 90% [1–3]. Many of these patients suffer from injurious falls and need to seek medical attention [1–3]. Therefore, valid risk estimation measures are of high clinical importance to identify patients prone to falls, and to initiate fall prevention strategies early. One major characteristic in cerebellar gait disorders is a high variability of the spatial and temporal gait parameters [4, 5]. Increased gait variability was found to be associated with falls in patients with hereditary as well as sporadic ataxia [5, 6], and may therefore serve as a predictive measure for the identification of patients at high risk of falling. However, risk factors are most likely specific to certain fall mechanisms. For example, while a sudden trip may be due to an impaired multi-joint coordination during locomotion, the decisive factor for falling over an obstacle could be lack of visuomotor control or attention. We therefore studied the incidence and causes of falls in patients with cerebellar gait disorders to then examine if increased gait variability can predict the occurrence of * Cornelia Schlick [email protected]‑muenchen.de 1
German Center for Vertigo and Balance Disorders, University Hospital Munich, Ludwig-MaximiliansUniversity, Munich, Germany
2
Department of Neurology, University Hospital Munich, Lud wig-Maximilians-University, Munich, Germany
3
Institute of Clinical Neurosciences, University Hospital Munich, Ludwig-Maximilians-University, Munich, Germany
4
Schön Klinik Bad Aibling, Bad Aibling, Germany
different falls, categorized according to their fall mechanism. In a prospective cohort study on fall risk in patients with vertigo and balance disorders (trial number: DRKS00006243), twenty-four patients with cerebellar gait disorders were included (sporadic adult-onset ataxia n = 7, spinocerebellar ataxia type II n = 3, spinocerebellar ataxia type III n = 3, paraneoplastic n = 1, Friedreich’s ataxia n = 10). At baseline, symptom severity was classified using the scale for the assessment and rating of ataxia (SARA) [7]. Gait was assessed on a 6.7 m pressure-sensitive sensor mat (GAITRite, CIR System, Havertown, USA). Patients were asked to walk over the mat in different walking conditions. No walking aids were used during the recordings. The coefficients of variation (CV) of stride time and stride length during preferred walking speed were taken for the analysis. A detailed method description of the gait measurements and data processing can be found in [5]. Falls were recorded using a fall diary and monthly telephone interviews during a 6-month follow-up. Frequency, severity and causes of falls were captured. All fall events were then grouped according to the Hopkins Fall Grading Scale [8] and categorized by their fall mechanism. The association between the most frequent fall categories and gait variability was investigated using logistic regression analysis. The patients were on average 47.4 (± 14.0) years old (8 females). The mean SARA score was 12.2 (± 4.4) points, ranging from 3 to 18 points. Twelve patients used a walking frame, 10 of them outside and two of them inside their home environment. Table 1a displays the 6 months incidence of falls and their severity. Three major fall mechanisms were identified and categorized as: (1) transitions from one body position to another, e.g., from lying to standing, (2) tripping while unperturbed walking and (3) managing stairs (Fig. 1). Among these categories, only falls due to tripping while unperturbed walking
13
Vol.:(0123456789)
J Neurol
Table 1 (a) Frequency and severity of falls in 24 patients with various cerebellar ataxias. (b) Association between the three major fall categories and gait variability
(a) Falls within 6 months Near-fall (Hopkins 1) Fall, no or mild injury (Hopkins 2) Fall requiring medical attention (Hopkins 3) Fall requiring hospital admission (Hopkins 4)
Falls, n (%)
Fallersa, n (%)
135 (100) 81/135 (60) 53/135 (39) 1/135 (1) 0/135
20/24 (83) 15/24 (63) 15/24 (63) 1/24 (4) 0/24
Odds ratiob
(b) Falls due to
Change in position Trip while unperturbed walking Managing stairs
Stride time CVc
Stride length CVc
SARA score
1.0 [0.7;1.4] 3.9 [1.2;12.5] 1.0 [0.7;1.4]
1.3 [0.9;1.8] 2.5 [1.1; 6.1] 1.0 [0.8;1.3]
1.1 [0.8;1.4] 2.0 [1.1;4.0] 1.0 [0.8;1.2]
a
Patient reporting at least one fall during 6 months
b c
Adjusted for age and gender
Coefficient of variation
Change in position Trip while unperturbed walking Managing stairs Other Trip over an obstacle Slippery / uneven terrain Loss of strength Trip while handling objects Cause not known / not remembered Poor visibility Trip while using public transportation Hastiness 5
10
15
20
25
Number of falls (total n = 135)
Fig. 1 Number of a total of 135 falls categorized by fall mechanism
The findings of this study give differential information on the relationship between gait variability and the risk of falls, with respect to different fall mechanisms. Gait variability, that is known to be a marker for dynamic stability of the locomotor pattern, is associated with trip-related falls during steady state walking, but not with falls during more complex balance tasks. This finding implies that increased stride time variability is a good measure to quantify locomotor pacemaker control and coordination during walking [6], and that these features are relevant for falls with a tripping mechanism. However, gait variability carries less information about flexibility and adaptability of the locomotor pattern during complex balance tasks that involve shifting weight during turns, body transitions and stair walking. Clinically, the study indicates that gait fluctuation measures alone are not completely sufficient for characterizing dynamic stability and fall risk in patients with cerebellar gait disorders. It is therefore desirable to investigate and include other factors to untangle dynamic stability properties during different fall mechanisms in these patients. Acknowledgements The work was supported by the Federal Ministry for Education and Science (BMBF, IFB01EO1401) of Germany. Compliance with ethical standards
were associated with an increase in stride time CV and stride length CV (Table 1b). Similarly, the total SARA score was predictive of falls due to tripping while unperturbed walking alone (Table 1b). The total SARA score was positively correlated with the gait variability measures (stride time CV: rSpearman = 0.6, p
