Tracking and Classification of Head Movement for Augmentative and Alternative Communication Systems

The use of assistive technologies can mitigate or reduce the challenges faced by individuals with motor disabilities to use computer systems. However, those who feature severe involuntary movements often have fewer options at hand. This work describes an application that can recognize the user’s head using a conventional webcam, track its motion, model the desired functional movement, and recognize it to enable the use of a virtual keyboard. The proposed classifier features a flexible structure and may be personalized for different user need. Experimental results obtained with participants with no neurological disorders have shown that classifiers based on Hidden Markov Models provided similar or better performance than a classifier based on position threshold. However, motion segmentation and interpretation modules were sensitive to involuntary movements featured by participants with cerebral palsy that took part in the study.

‘Hand mechanogram’ in epilepsia partialis continua

Epilepsia partialis continua manifests as low-frequency, rhythmic involuntary movements of a focal body part. We report a young man, HIV-positive and with syphilis, who developed right-hand epilepsia partialis continua associated with a small left-sided cortico-subcortical frontal lesion. A pen and paper test provided ‘mechanographic’ data on frequency, amplitude and rhythmicity of the hand movements, helping distinguish it from other causes of low-frequency repetitive hand movements.

Classification and Approach to Movement Disorders

Movement disorders are conventionally divided into 2 major categories. Hyperkinetic movement disorders (also called dyskinesias) are excessive, often repetitive, involuntary movements that intrude into the normal flow of motor activity. This category includes chorea, dystonia, myoclonus, stereotypies, tics, and tremor. Hypokinetic movement disorders are akinesia (lack of movement), hypokinesia (reduced amplitude of movement), bradykinesia (slow movement), and rigidity. Parkinsonism is the most common hypokinetic movement disorder. In childhood, hyperkinetic disorders are common, whereas hypokinetic movement disorders are relatively uncommon.

Hyperkinetic Movement Disorders: Chorea, Tic, and Dystonia

Hyperkinetic movement disorders are characterized by an excess of movement. This chapter outlines the classification, causes, and treatment of chorea, tic disorders, and dystonia. The term chorea refers to dancelike irregular, arrhythmic, rapid, involuntary movements that appear to flow between muscle groups. Athetosis, a slower and twisting dystonialike movement, may be superimposed with chorea, leading to choreoathetosis. Ballism is a form of high-amplitude and proximal chorea that has the appearance of flailing movement.

Dopaminergic co-transmission with sonic hedgehog inhibits abnormal involuntary movements in models of Parkinson’s disease and L-Dopa induced dyskinesia

L-Dopa induced dyskinesia (LID) is a debilitating side effect of dopamine replacement therapy for Parkinson’s Disease. The mechanistic underpinnings of LID remain obscure. Here we report that diminished sonic hedgehog (Shh) signaling in the basal ganglia caused by the degeneration of midbrain dopamine neurons facilitates the formation and expression of LID. We find that the pharmacological activation of Smoothened, a downstream effector of Shh, attenuates LID in the neurotoxic 6-OHDA- and genetic aphakia mouse models of Parkinson’s Disease. Employing conditional genetic loss-of-function approaches, we show that reducing Shh secretion from dopamine neurons or Smoothened activity in cholinergic interneurons promotes LID. Conversely, the selective expression of constitutively active Smoothened in cholinergic interneurons is sufficient to render the sensitized aphakia model of Parkinson’s Disease resistant to LID. Furthermore, acute depletion of Shh from dopamine neurons through prolonged optogenetic stimulation in otherwise intact mice and in the absence of L-Dopa produces LID-like involuntary movements. These findings indicate that augmenting Shh signaling in the L-Dopa treated brain may be a promising therapeutic approach for mitigating the dyskinetic side effects of long-term treatment with L-Dopa.

A Critical Review of Alien Limb-Related Phenomena and Implications for Functional Magnetic Resonance Imaging Studies

Consensus criteria on corticobasal degeneration (CBD) include alien limb (AL) phenomena. However, the gist of the behavioral features of AL is still “a matter of debate.” CBD-related AL has so far included the description of involuntary movements, frontal release phenomena (frontal AL), or asomatognosia (posterior or “real” AL). In this context, the most frequent symptoms are language and praxis deficits and cortical sensory misperception. However, asomatognosia requires, by definition, intact perception and cognition. Thus, to make a proper diagnosis of AL in the context of CBD, cognitive and language dysfunctions must be carefully verified and objectively assessed. We reviewed the current literature on AL in CBD and now propose that the generic use of the term AL should be avoided. This catchall AL term should instead be deconstructed. We propose that the term AL is appropriate to describe clinical features associated with specific brain lesions. More discrete sets of regionally bound clinical signs that depend on dysfunctions of specific brain areas need to be assessed and presented when posing the diagnosis. Thus, in our opinion, the AL term should be employed in association with precise descriptions of the accompanying involuntary movements, sensory misperceptions, agnosia-asomatognosia contents, and the presence of utilization behavior. The review also offers an overview of functional magnetic resonance imaging-based studies evaluating AL-related phenomena. In addition, we provide a complementary set of video clips depicting CBD-related involuntary movements that should not mistakenly be interpreted as signs of AL.

Successful multiple burr hole openings for limb-shaking transient ischemic attack due to moyamoya disease: illustrative case

BACKGROUND Limb-shaking transient ischemic attacks (LS-TIAs) are a rare form of TIAs that present as involuntary movements of the limbs and indicate severe cerebral hypoperfusion. LS-TIAs are often reported in patients with carotid artery stenosis but can also affect patients with intracranial artery stenosis and moyamoya disease (MMD). OBSERVATIONS A 72-year-old woman presented with repeated episodes of involuntary shaking movements of the right upper limb. Cerebral angiography revealed complete occlusion of the M1 segment of the left middle cerebral artery (MCA), and the left hemisphere was supplied by moyamoya vessels. She was treated with left direct revascularization without complications, and her involuntary movements subsided. However, she demonstrated involuntary shaking movements of the right lower limb 2 months postoperatively. Cerebral angiography revealed complete occlusion of the A1 segment of the left anterior cerebral artery (ACA). The multiple burr hole opening (MBHO) procedure was performed to improve perfusion in the left ACA territory and after 3 months, the patient’s symptoms resolved. LESSONS This case demonstrated that LS-TIAs can also develop as ischemic symptoms due to MMD. Moreover, instances of LS-TIA of the upper and lower limbs developed separately in the same patient. The patient’s symptoms improved with direct revascularization and MBHO.