# Brain abnormalities underlying limb apraxia in corticobasal degeneration: an fMRI study

Olivier Beauchet, Pascal Giraux, Fabien Schneider, Roland Peyron, Fabrice Barral, Bernard Laurent

► To cite this version:

Olivier Beauchet, Pascal Giraux, Fabien Schneider, Roland Peyron, Fabrice Barral, et al. Brain abnormalities underlying limb apraxia in corticobasal degeneration: an fMRI study. Dialogues in Clinical Neuroscience, 2001, 3 (3), pp.214-215. 10.31887/DCNS.2001.3.3/obeauchet. hal-04949002

HAL Id: hal-04949002

https://hal.science/hal-04949002v1

Submitted on 14 Feb 2025

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# Brain abnormalities underlying limb apraxia in corticobasal degeneration: an fMRI study

Corticobasal degeneration is a neurodegenerative disease characterized by cortical dysfunction and extrapyramidal signs. The most consistent symptom is a unilateral limb apraxia, which consists of an isolated disorder of gestural production involving primarily the upper limb. The objective of this study is to investigate the functional abnormalities that may underlie motor dysfunction, and those which might correlate to the severity of limb apraxia.

## Methods

* The event-related experimental design (Figure 1) was based on regular alternation of an activation period (5.3 s) and a rest period (21.3 s).

* The activation period involved 2 digital sequences performed on the normal and the symptomatic side:

- simple: opposition movement of the thumb on II, III, IV, V, IV, III, and II fingers;

- complex: opposition movement of the thumb on II, IV, III, V, III, and IV fingers.

* The acquisition of images was divided into 4 sessions (2 for the right hand, 2 for the left hand). Each session comprised 10 activations (5 simple and 5 complex digital sequences in a randomized order).

* Magnetic resonance imaging (MRI) was performed using a 1.0 T Siemens Impact; Statistical Parametric Map (SPM99) software and MATLAB (versions 4.2b and 5.3, MathWorks, Natick, Mass) were used.

* Subtraction analysis compared each digital sequence (simple or complex) with the resting condition. Significant differences were accepted at threshold of *P*<0.001 corresponding to a Z score of 3.09. The threshold in *k* defining the minimal extent of a cluster was 18 voxels.

## Results

The characteristics of the patients included in the study are presented in Table 1 and the results are shown in Table II and Figures 2 to 5.

<figure><img src="image_2.png" /><figcaption>Figure 1. Experimental design.</figcaption></figure>

Activation periods = 5.3 s
Rest periods = 21.3 s.

<table><caption>Table I. Clinical characteristics of the population.</caption><thead><tr><th></th><th>P1</th><th>P2</th><th>P3</th><th>P4</th></tr></thead><tbody><tr><td>Age at onset (years)/sex</td><td>55/M</td><td>76/F</td><td>56/M</td><td>71/M</td></tr><tr><td>Disease duration (years)</td><td>2</td><td>3</td><td>5</td><td>5</td></tr><tr><td>Handedness</td><td>R</td><td>R</td><td>R</td><td>R</td></tr><tr><td>Affected side</td><td>L</td><td>R</td><td>L</td><td>R</td></tr><tr><td>UPDRS (4)</td><td>1</td><td>1</td><td>2</td><td>3</td></tr><tr><td>Levodopa resistance</td><td>+</td><td>+</td><td>+</td><td>+</td></tr><tr><td>Sensory/motor deficit</td><td>-</td><td>-</td><td>-</td><td>-</td></tr><tr><td>Oculomotor disorders</td><td>-</td><td>-</td><td>+</td><td>+</td></tr><tr><td>Myoclonus/dystonia/alien limb</td><td>-</td><td>-</td><td>-</td><td>-</td></tr><tr><td>Dementia</td><td>-</td><td>-</td><td>Moderate</td><td>Moderate</td></tr><tr><td>Executive apraxia</td><td>+</td><td>+</td><td>+</td><td>+</td></tr><tr><td>Conceptual apraxia</td><td>-</td><td>-</td><td>-</td><td>-</td></tr></tbody></table>

P, patient; M, male; F: female; +, presence; -, absence; R, right; L, left; UPDRS, Unified Parkinson Disease Rating Scale.
<figure><img src="image_3.png" /><figcaption>Figure 2. Motor task on normal side: simple sequences versus rest.</figcaption></figure>

<figure><img src="image_4.png" /><figcaption>Figure 3. Motor task on normal side: complex sequences versus rest.</figcaption></figure>

<figure><img src="image_5.png" /><figcaption>Figure 4. Motor task on affected side: simple sequences versus rest.</figcaption></figure>

<figure><img src="image_6.png" /><figcaption>Figure 5. Motor task on affected side: complex sequences versus rest.</figcaption></figure>

<table><caption>Table II. Motor task (performance of digital sequences).</caption><thead><tr><th rowspan="2"></th><th colspan="2">Simple</th><th colspan="2">Complex</th></tr><tr><th>Normal side</th><th>Affected side</th><th>Normal side</th><th>Affected side</th></tr></thead><tbody><tr><th>Mean time (s)</th><td>3.8 (±0.3)</td><td>4.6 (±0.3)</td><td>4.2 (±0.3)</td><td>5.1 (±0.2)</td></tr><tr><th>Amplitude (0-3)</th><td>2.5 (±0.5)</td><td>2.3 (±0.4)</td><td>2.3 (±0.4)</td><td>2.0 (±0.1)</td></tr><tr><th>% error</th><td>3.3 (±2.4)</td><td>11.8 (±11)</td><td>5.3 (±2.9)</td><td>16.3 (±14)</td></tr><tr><th>% sequences &lt;7 movements</th><td>2.0 (±2.1)</td><td>6.3 (±8.2)</td><td>3.0 (±2.5)</td><td>11.8 (±13)</td></tr></tbody></table>

## Conclusion

The deficit of premotor activity seems to confirm a preferential disorder of this cerebral area in corticobasal degeneration. The parietal activity and the associated modifications plead for a cerebral plasticity based on neuronal recruitment. ☐