Body awareness disorders: dissociations between body-related visual and somatosensory information

The importance of recovering body awareness in post-stroke rehabilitation: insights from clinical case reports

Introduction

Body awareness (BA) is the process of gaining sensory awareness based on the physiological states and actions of the body. It is influenced by an individual's attitudes, perceptions, beliefs, and experiences within the social and cultural contexts. Following a stroke, impairments in BA are thought to be widespread and could have a significant impact on recovery results. Regaining body awareness, however, is often neglected in the neurorehabilitation field. This study aimed to assess body image perception in two stroke patients and the potential effect of motor and cognitive rehabilitative treatments on possible improvement of BA.

Methods

Patients were evaluated through a multidimensional neuropsychological assessment before and after a 3-month motor and cognitive rehabilitative training. Sessions were scheduled 6 times per week with a total duration of 3 h per session.

Results

After the neurorehabilitative treatment, both patients showed an improvement in BA, cognition, mood, and motor skills. Differences emerged related to the progression and improvement of their respective performances.

Discussion

The causes of these differences could include the following: different brain areas affected, the ischemic or hemorrhagic nature of the stroke, age, and sex. Further research is needed to better understand the differences and similarities in the correlations between deficit and lesional sites. Structured and early multidisciplinary intervention can certainly guarantee a better functional recovery for patients after a stroke. However, in this study we show how complementary assessment methods (such as human figure drawing) may be highly informative in choosing treatment modalities and verifying rehabilitation outcomes.

Feeling without localizing: exploring tactile misperception in a patient with uncommon parietal left brain damage

Introduction

We report a very unique clinical presentation of a patient who complained, after a left parietal brain damage, about feeling tactile stimulations on his right upper limb without being able to localize them.

Methods

Using a single case study approach, we report three experiments relying on several custom-made tasks to explore the different levels of somatosensory information processing, ranging from somato-sensation to somato-representation.

Results

Our results showed a preserved ability to localize tactile stimuli applied on the right upper limb when using pointing responses while the ability to localize was less efficient when having to name the stimulated part (akin Numbsense). When the stimuli were applied on more distal locations (i.e., on the hand and on fingers), the number of correct responses decreased significantly independently of the modality of response. Finally, when visually presented with a stimulus delivered on the hand of an examiner in synchrony with the stimulation on the hidden hand of the patient, responses were largely influenced by the visual information available. Altogether, the convergence of these different customized tasks revealed an absence of autotopagnosia for motor responses for the right upper limb, associated with altered abilities to discriminate stimulus applied on distal and restricted/closer zones in the hand.

Discussion

The somato-representation of our patient seemed to significantly rely on visual information, leading to striking deficits to localize tactile stimuli when vision and somesthesic afferences are discordant. This case report offers a clinical illustration of pathological imbalance between vision and somesthesia. Implications of these troubles in somato-representation on higher cognitive level processes are discussed.

Invisible doppelgänger and body image disorders in right superior parietal lobule stroke, a case series

Autoscopic phenomena or an "invisible doppelgänger" refer to the illusory reduplication of one's own body. Body image disorder involves distorted perception or decreased body awareness. In the literature, feeling of presence (FOP) is rarely presented with a circumscribed cerebral pathology due to acute vascular lesions, and concomitant FOP and disorders of the body image or the body schema (BIBS) have rarely been reported. We present three cases of both FOP and BIBS disorders. All patients reported the two types of symptoms almost simultaneously: The first patient had the symptom of somatoparaphrenia characterized by deny ownership of the hand and feeling that it does not belong to her, the second patient had the sign of fading limb presented with misuse of his left hand when it was not under visual control and could not mentally represent and locate this part of the body in space, and the third patient had autotopagnosia; he was unable to localize any touched area below the elbow and knee. All patients had right parietal ischemic lesions involving the superior parietal lobule, and two patients had an adjacent additional precuneal involvement. Based on the cases presented here, it is plausible that BIBS may develop in addition to FOP, especially in lesions involving the superior parietal lobule and precuneus.

The Empowering Effect of Embodied Awareness Practice on Body Structural Map and Sensorimotor Activity: The Case of Feldenkrais Method

While outcomes of embodied awareness practices in terms of improved posture and flexibility, movement efficiency, and well-being are often reported, systematic investigations of such training effects and of the actual nature, extent, and neurofunctional correlates of learning mechanisms thought to lie at the core of such practices are very limited. The present study focused on the Feldenkrais method (FM), one of the most established embodied awareness practices, and aimed at investigating the neurofunctional outcomes of the somatic learning process at the core of the method by testing the modulations induced by a standardized FM protocol on the complexity of practicers’ body structural map and on the activity of their sensorimotor network during different movement-related tasks (i.e., gestures observation, execution, and imagery). Twenty-five participants were randomly divided into an experimental group—which completed a 28-session FM protocol based on guided group practice—and a control group, and underwent pre-/post-training psychometric and electrophysiological assessment. Data analysis highlighted, at the end of the FM protocol, a significant increase of EEG markers of cortical activation (task-related mu desynchronization) in precentral regions during action observation and in central regions during action execution and imagery. Also, posterior regions of the sensorimotor network showed systematic activation during all the action-related tasks.