Paratonia in Dementia: A Systematic Review

From one to many: Hypertonia in schizophrenia spectrum psychosis an integrative review and adversarial collaboration report

Different types of resistance to passive movement, i.e. hypertonia, were described in schizophrenia spectrum disorders (SSD) long before the introduction of antipsychotics. While these have been rediscovered in antipsychotic-naïve patients and their non-affected relatives, the existence of intrinsic hypertonia vs drug-induced parkinsonism (DIP) in treated SSD remains controversial. This integrative review seeks to develop a commonly accepted framework to specify the putative clinical phenomena, highlight conflicting issues and discuss ways to challenge each hypothesis and model through adversarial collaboration. The authors agreed on a common framework inspired from systems neuroscience. Specification of DIP, locomotor paratonia (LMP) and psychomotor paratonia (PMP) identified points of disagreement. Some viewed parkinsonian rigidity to be sufficient for diagnosing DIP, while others viewed DIP as a syndrome that should include bradykinesia. Sensitivity of DIP to anticholinergic drugs and the nature of LPM and PMP were the most debated issues. It was agreed that treated SSD should be investigated first. Clinical features of the phenomena at issue could be confirmed by torque, EMG and joint angle measures that could help in challenging the selectivity of DIP to anticholinergics. LMP was modeled as the release of the reticular formation from the control of the supplementary motor area (SMA), which could be challenged by the tonic vibration reflex or acoustic startle. PMP was modeled as the release of primary motor cortex from the control of the SMA and may be informed by subclinical echopraxia. If these challenges are not met, this would put new constraints on the models and have clinical and therapeutic implications.

A Biopsychosocial Model of Mealtime Management in Persons with Dementia, an Asset-Based Approach to Patient-Centered Care

Considering the rapid increase in the population over the age of 65, there is increasing need to consider models of care for persons with dementia (PWD). One common deficit associated with dementia progression is difficulty with successful participation in mealtimes. Difficulty participating in mealtimes in PWD is not the result of one factor, but rather a confluence of biological, psychological, and social characteristics common in dementia. Factors leading to mealtime difficulties for PWD may include changes in cognitive status, altered sensorimotor functioning, and increased reliance on caregiver support. The complex nature of biological, psychological, and social factors leading to mealtime difficulty highlights the need for a pragmatic model that caregivers can utilize to successfully support PWD during mealtimes. Existing models of dementia and mealtime management were reviewed and collated to create a model of mealtime management that considers this complex interplay. The Biopsychosocial Model of Mealtime Management builds on past research around patient-centered care and introduces an asset-based approach to capitalize on a PWD's retained capabilities as opposed to compensating for disabilities associated with dementia. We hope this model will provide a framework for caregivers to understand what factors impact mealtime participation in PWD and provide appropriate means on intervention.

Electromyographic Patterns of Paratonia in Normal Subjects and in Patients with Mild Cognitive Impairment or Alzheimer’s Disease

Background: Information on prevalence, pathophysiology, and clinical assessment of paratonia are scarce. In a previous study, we suggested that surface electromyography (EMG) can be used to assess paratonia. Objective: To assess clinical and EMG features of paratonia in both patients with cognitive impairment and healthy subjects. Methods: We examined 18 patients with Alzheimer’s disease (AD), 21 patients with mild cognitive impairment (MCI), 30 healthy seniors (seniors), and 30 healthy juniors (juniors). Paratonia were assessed using the “Paratonia Scale”. EMG bursts were recorded from biceps and triceps during manually applied passive movements of elbow joint. Continuous (sinusoidal) and discontinuous (linear) movements were applied at 2 different velocities (fast and slow). Results: In comparison to juniors, seniors had higher clinical scores. In comparison to seniors, AD had higher oppositional scores, while MCI had higher facilitatory scores. EMG activity during passive movements correlated with paratonia clinical scores, was velocity-dependent and increased with movement repetition, most effectively for sinusoidal movements. Similar EMG activity was detected in not paratonic muscles. Conclusion: Paratonia increases with normal aging and cognitive decline progression. While facilitatory paratonia is due to involuntary contraction of the shortening muscle, oppositional paratonia is due, at least partially, to involuntary contraction of the lengthening muscle. Most characteristic feature of this muscle contraction is the progressive increase with movement repetition, that helps distinguish oppositional paratonia from spasticity and rigidity. A similar EMG activity is detected in not paratonic muscles, showing that, during tone assessment, the descending motor system is incompletely inactivated also in normotonic muscles.

Disorders of Movement due to Acquired and Traumatic Brain Injury

Purpose of Review

Both traumatic and acquired brain injury can result in diffuse multifocal injury affecting both the pyramidal and extrapyramidal tracts. Thus, these patients may exhibit signs of both upper motor neuron syndrome and movement disorder simultaneously which can further complicate diagnosis and management. We will be discussing movement disorders following acquired and traumatic brain injury.

Recent Findings

Multiple functions including speech, swallowing, posture, mobility, and activities of daily living can all be affected. Medical treatment and rehabilitation-based therapy can be especially challenging due to accompanying cognitive deficits and severity of the disorder which can involve multiple limbs in addition to muscles of the face and axial skeleton. Tremor and dystonia are the most reported movement disorders following traumatic brain injury. Dystonia and myoclonus are well documented following hypoxic ischemic brain injuries. Electrophysiological studies such as dynamic surface poly-electromyography can assist with identifying phenomenology, especially differentiating between jerk-like phenomenon and help guide further work up and management. Management with medications remains challenging due to potential adverse effects. Surgical interventions including stereotactic surgery, deep brain stimulation, and intrathecal baclofen pumps have been reported, but most of the evidence supporting them has been limited to primarily case reports except for post-traumatic tremor.

Summary

Brain injury can lead to motor disorders, movement disorders, visual (processing) deficits, and vestibular deficits which often coexist with cognitive deficits making it challenging to treat and rehabilitate these patients. Unfortunately, the evidence regarding the medical management and rehabilitation of brain injury patients with movement disorders is sparse and leaves much to be desired.

Muscle Tone Physiology and Abnormalities

The simple definition of tone as the resistance to passive stretch is physiologically a complex interlaced network encompassing neural circuits in the brain, spinal cord, and muscle spindle. Disorders of muscle tone can arise from dysfunction in these pathways and manifest as hypertonia or hypotonia. The loss of supraspinal control mechanisms gives rise to hypertonia, resulting in spasticity or rigidity. On the other hand, dystonia and paratonia also manifest as abnormalities of muscle tone, but arise more due to the network dysfunction between the basal ganglia and the thalamo-cerebello-cortical connections. In this review, we have discussed the normal homeostatic mechanisms maintaining tone and the pathophysiology of spasticity and rigidity with its anatomical correlates. Thereafter, we have also highlighted the phenomenon of network dysfunction, cortical disinhibition, and neuroplastic alterations giving rise to dystonia and paratonia.