Cortico-thalamic disconnection in a patient with supernumerary phantom limb

Victor Parant (1848-1924) and the first report of psychosis in the course of Parkinson's disease with dementia

Until the beginning of the twentieth century, neurologists considered that mental disorders in the course of Parkinson's disease (PD) occurred in the terminal phases of the disease or were due to coincidental pathologies. Benjamin Ball (1834-1893), in 1881 and 1882, drew attention to the frequency of cognitive and depressive disorders in PD. In 1883, Victor Parant (1848-1924), referring to Ball's work, published the first detailed observation of a PD patient with dementia and psychotic symptoms. Parant was an alienist running a private clinic for mental diseases in Toulouse, France. One of his main interests was the question of the responsibility of the insane, and he was called upon as a forensic expert in several cases. In this context, Parant examined a man who had been suffering from PD for several years, and later developed concurrently severe cognitive impairment and psychotic disorders. The patient would meet modern criteria for PD-associated psychosis: he had multimodal hallucinations (visual, auditory and somatic), visual illusions, and paranoid delusions. He also reported unusual symptoms: supernumerary limbs and Alice in Wonderland syndrome. Parant forwarded the far-sighted hypothesis that cognitive and psychotic disorders were due to the extension of PD lesions within the brain. The unheralded work of Victor Parant should be recognized in the history of neuropsychiatry.

Reduced Self-Awareness Following a Combined Polar and Paramedian Bilateral Thalamic Infarction. A Possible Relationship With SARS-CoV-2 Risk of Contagion?

Reduced self-awareness is a well-known phenomenon investigated in patients with vascular disease; however, its impact on neuropsychological functions remains to be clarified. Importantly, selective vascular lesions provide an opportunity to investigate the key neuropsychological features of reduced self-awareness in neurocognitive disorders. Because of its rarity, we present an unusual case of a woman affected by a combined polar and paramedian bilateral thalamic infarction. The patient underwent an extensive neuropsychological evaluation to assess cognitive, behavioral, and functional domains, with a focus on executive functions. She was assessed clinically in the acute phase and after 6 months from the stroke, both clinically and by magnetic resonance imaging. The patient developed a cognitive impairment, characterised by prevalent executive dysfunction associated with reduced self-awareness and mood changes, in terms of apathy and depression. Such condition persisted after 6 months. In May 2020, the patient underwent the serology test in chemiluminescence to detect IgG antibodies against SARS-CoV-2. The result of the quantitative test highlighted a high probability of previous contact with the virus. We suggest that reduced self-awareness related to executive dysfunction and behavioral changes may be due to combined polar and paramedian bilateral thalamic lesion. Metacognitive–executive dysfunction affecting the instrumental abilities of everyday life might make people less able to take appropriate precautions, facilitating the risk of SARS-CoV-2 contagion.

Management of nonpainful supernumerary phantom limbs after incomplete spinal cord injury with visual-tactile feedback therapy: a case report

INTRODUCTION

Supernumerary phantom limb (SPL) is an uncommon phantom sensation where the patient experiences the illusory presence of one or more limbs in addition to their existing limbs. SPL after a spinal cord injury (SCI) is rare with few documented cases. There is minimal treatment guidance available, with some reports of visual-tactile feedback therapy used to manage SPL.

CASE PRESENTATION

A 43-year-old male sustained a C4 ASIA Impairment Scale grade C SCI, developing the sensation of two SPL arms originating from his shoulders 6 days after injury. He developed a self-directed method of visual-tactile feedback as a means to improve the SPL sensations, consisting of shrugging his shoulders repeatedly for 1 min while observing the movement of his actual arms. After completion of this routine, the SPL moved to the same location as his arms, providing relief. Also, an elastic band was placed on a sensate region of his arm, providing additional visual-tactile feedback. The SPL improved and resolved by day 45.

DISCUSSION

SPL after SCI is poorly characterized, usually occurring within 6-7 days of injury after a complete or incomplete cervical SCI. While the mechanism is unclear, the inability to integrate visual, tactile, and proprioceptive information after deafferentation may contribute to development. Similarities between SPL and phantom limb sensation after an amputation have resulted in the use of visual and visual-tactile feedback therapy for painful SPL management. This is the first case documenting successful use of visual-tactile feedback therapy to manage nonpainful SPL.

Effects of combined rTMS and visual feedback on the rehabilitation of supernumerary phantom limbs in a patient with spinal cord injury: A case report

BACKGROUND

Supernumerary phantom limb (SPL) caused by spinal cord injury (SCI) has previously been reported in several studies. However, the mechanisms and management of SPL in SCI patients are still not fully understood. Herein, we report a rare case of SPL in a patient with incomplete SCI.

CASE SUMMARY

A 46-year-old man complained of four hands 7 d after SCI. He was diagnosed with SPL complicated with actual limb neuropathic pain. Following a period of treatment with neurotrophic agents and Chinese traditional and analgesic medications, SPL symptoms and actual limb pain did not improve. However, his symptoms gradually lessened after combined treatment with high-frequency repetitive transcranial magnetic stimulation (rTMS), a promising neuromodulation technique, over the M1 cortex and visual feedback. After 7 wk of this treatment, SPL disappeared completely and actual limb pain was significantly relieved.

CONCLUSION

Cerebral plasticity changes may be a mechanism underlying the occurrence of non-painful SPL in SCI patients, and high-frequency rTMS applied to the M1 cortex could be a promising treatment method for SPL.

Influence of reward learning on visual attention and eye movements in a naturalistic environment: A virtual reality study

Rewards constitute crucial signals that motivate approach behavior and facilitate the perceptual processing of objects associated with favorable outcomes in past encounters. Reward-related influences on perception and attention have been reliably observed in studies where a reward is paired with a unidimensional low-level visual feature, such as the color or orientation of a line in visual search tasks. However, our environment is drastically different and composed of multidimensional and changing visual features, encountered in complex and dynamic scenes. Here, we designed an immersive virtual reality (VR) experiment using a 4-frame CAVE system to investigate the impact of rewards on attentional orienting and gaze patterns in a naturalistic and ecological environment. Forty-one healthy participants explored a virtual forest and responded to targets appearing on either the left or right side of their path. To test for reward-induced biases in spatial orienting, targets on one side were associated with high reward, whereas those on the opposite side were paired with a low reward. Eye-movements recording showed that left-side high rewards led to subsequent increase of eye gaze fixations towards this side of the path, but no such asymmetry was found after exposure to right-sided high rewards. A milder spatial bias was also observed after left-side high rewards during subsequent exploration of a virtual castle yard, but not during route turn choices along the forest path. Our results indicate that reward-related influences on attention and behavior may be better learned in left than right space, in line with a right hemisphere dominance, and could generalize to another environment to some extent, but not to spatial choices in another decision task, suggesting some domain- or context-specificity. This proof-of-concept study also outlines the advantages and the possible drawbacks of the use of the 3D CAVE immersive platform for VR in neuroscience.