Lecture 17 - Cerebellum and Basal Ganglia Disorders PDF

Cerebellum and Basal Ganglia Disorders Kelly Roballo D.M.V.; PhD Learning Objectives 1. Identify the neurological disturbances that can result from disease or damage in different regions of the cerebellum. 2. Identify the appropriate signs of ataxia 3. Identify the appropriate signs of rigidity, d...

Cerebellum and Basal Ganglia Disorders Kelly Roballo D.M.V.; PhD Learning Objectives 1. Identify the neurological disturbances that can result from disease or damage in different regions of the cerebellum. 2. Identify the appropriate signs of ataxia 3. Identify the appropriate signs of rigidity, dyskinesias, akinesia, and tremor for Parkinsonism, chorea, hemiballism, and athetosis. 4. Describe the rationale for treatment of Parkinsonism with anticholinergic drugs, L-DOPA, or transplantation of catecholamine-producing cells. 5. Identify what are the major brain regions affected in the basal ganglia disorders Chapter 8 and 9- Basic Clinical neuroscience book. Cerebellum X Basal Ganglia Review article, neuroscience, The basal ganglia and the cerebellum: nodes in an integrated network; 2018 Cerebellar disorders Somatotopic Organization of Multimodal Inputs to the Cerebellum Blumenfeld, Neuroanatomy through Clinical Cases n Noradrenergic inputs from the locus coeruleus and serotonergic inputs from the raphe nuclei project diffusely throughout the cerebellar cortex n These inputs play a neuromodulatory role Ataxia • Is characterized by abnormalities in the timing, range, force, speed, and sequencing of muscle contractions and resultant movements. • Delayed slowing movements and overshooting target. Finger-Nose-Finger Test n In ataxia, the movements have an irregular, wavering course that seems to consist of continuous overshooting, overcorrecting, and then overshooting again around the intended trajectory n Appendicular ataxia: Coordinated actions of agonist and antagonist muscles acting on multiple joints, including the shoulder, elbow, and wrist, are required to smoothly perform this movement in a normal fashion Blumenfeld, Neuroanatomy through Clinical Cases • Cerebellar lesions and disease tend to disrupt the modulation and coordination of ongoing movements. Thus, the hallmark of patients with cerebellar damage is difficulty producing smooth, well-coordinated movements. • Instead, movements tend to be jerky and imprecise, a pattern referred to as cerebellar ataxia. • Many of these difficulties in performing movements can be explained as disruption of the cerebellum's role in correcting errors in ongoing movements. • Normally, the cerebellar error correction mechanism ensures that movements are modified to cope with changing circumstances. • Truncal Ataxia: Lesions confined to the cerebellar vermis affect primarily the medial motor systems. Patients with such lesions therefore often have a widebased, unsteady “drunklike” gait • Appendicular ataxia: Lesions of the intermediate and lateral portions of the cerebellar hemisphere affect the lateral motor systems. Therefore, these patients have ataxia on movement of the extremities Cerebellum degeneration due to Chronic Alcohol Use • The pathological changes in a variety of neurological diseases provide insights about the function of the cerebellum. • In this example, chronic alcohol abuse has caused degeneration of the anterior cerebellum (arrows), while leaving other cerebellar regions intact. • The patient had difficulty walking but little impairment of arm movements or speech. n Ataxic Gait demonstration https://www.youtube.com/watch?v=JSyLnt3rLxs n Ataxic Gait Patient demonstration https://www.youtube.com/watch?v=lrerPzLtnY8 • Speech Rapid Alternating Movements Dysarthria Impaired speech articulation of cerebellar origin is characterized by being slow, indistinct, and scanning (scanning refers to decomposition of words into monosyllabic parts and loss of normal phrasing and intonation). • Rebound Increased range of movement with lack of normal recoil to original position is seen in cerebellar disease. • Hand Rapid Alternating Movements Movements are slow and irregular with imprecise timing. Inability to perform repetitive movements in a rapid rhythmic fashion is called dysdiadochokinesia. • Finger-to-nose Under (hypometria) and over (hypermetria) shooting of a target (dysmetria) and the decomposition of movement (the breakdown of the movement into its parts with impaired timing and integration of muscle activity) are seen with appendicular ataxia. • https://neurologicexam.med.utah.edu/adult/html/coordination_abnormal.html • Look the Hand rapid alternating movements (where is the injury?) • Foot rapid alternating movements Movements are slow and irregular with imprecise timing of agonist and antagonist muscle action. • Toe-to-finger Same as finger-to-nose except for the lower extremities. For both the upper and lower extremities, it is important to always compare right versus left. • Heel-to-shin The patient with ataxia of the lower extremity will have difficulty placing the heel on the knee with a side-to-side irregular over- and undershooting as the heel is advanced down the shin. Dysmetria on heel-to-shin can be seen in midline ataxia syndromes as well as cerebellar hemisphere disease so there is overlap between the two types of ataxias for this finding. • Station Patient's feet will be placed wider apart then usual in order to maintain balance (broad or wide-based station). Midline ataxias cause instability of station with eyes opened or closed. Ataxia is most prominent when sudden changes are needed such as turning, standing up or stopping. • https://neurologicexam.med.utah.edu/adult/html/coordination_abnormal.html Basal Ganglia disorders Positive and Negative signs • Positive: patient don’t want but it happens anyways/ patient can't prevent the movement to happen. Loss of control – abnormal pattern movement. (dyskinesia) • Negative: patient wants to perform but can't. Neurons no longer elicit an activity. (akinesia, bradykinesia) Parkinson’s Disease • Is a common idiopathic disease caused by loss of dopaminergic neurons in the substantia nigra pars compacta. It is characterized by asymmetrical ‘pillrolling’ resting tremor, bradykinesia, rigidity, and postural instability, which usually respond to therapy with levodopa. • The decreased blink rate and rigid and shuffling gate are typical of Parkinson’s disease. These problems result from a decreased input from the ventrolateral (VL) nucleus of the thalamus to the motor cortex of the brain. • This input, which is modulated by the basal ganglia, normally modifies descending cortical motor output to allow the individual to initiate voluntary movements at an appropriate pace. • Thalamic input is modulated by the basal ganglia via two basal ganglia pathways. The extent to which the VL nucleus is inhibited depends on the balance of activity in each pathway. • A- Section through the midbrain from a patient who died with Parkinson’s disease. Asymmetrical pallor affecting the right substantia nigra greater than the left can be seen, caused by degeneration of pigmented dopaminergic neurons • B- Typical Lewy body. It has a characteristic dense (pink) center with a lighter halo and is located in the cytoplasm of a darkly pigmented dopaminergic neuron (Dementia with Lewy bodies for differential diagnosis) • Parkinsonian Gait This man's gait is bradykinetic and his steps are smaller then usual. There is also the pill-rolling tremor in his hands. He turns “en bloc” and there is decreased facial expression. https://www.youtube.com/watch?v=j86omOwx0Hk Parkinson’s Disease Patient Presentation: • https://www.youtube.com/watch?v=IHDFQfmkKlg Huntington’s Disease • Is an autosomal dominant neurodegenerative condition characterized by a progressive, usually choreiform movement disorder, dementia, and psychiatric disturbances, ultimately leading to death. • The pathologic hallmark is progressive atrophy of the striatum, especially involving the caudate nucleus. • Usual age of onset is between 30 and 50 years, with prevalence of 4-5 cases per million. • Subtle eye movement abnormalities can be detected before other manifestations become apparent. These are slow saccades, impaired smooth pursuit, difficulty initiating saccades without moving the head or blinking. • The abnormal gene is mapped on chromosome 4, and it includes a region containing multiple repeats of the trinucleotide sequence CAG in tandem. (more repetitions of CAG over generations, start to have the symptoms younger… and younger) Behavior changes may occur before movement problems, and can include: • Behavioral disturbances • Hallucinations • Irritability • Moodiness • Restlessness or fidgeting • Paranoia • Psychosis Huntington Disease (HD) Abnormal and unusual movements include (involuntary): • Facial movements, including grimaces • Head turning to shift eye position • Quick, sudden, sometimes wild jerking movements of the arms, legs, face, and other body parts • Slow, uncontrolled movements • Unsteady gait Dementia that slowly gets worse, including: • Disorientation or confusion • Loss of judgment • Loss of memory • Personality changes • Speech changes Cross section of a brain of an adult with Huntington disease, illustrating marked striatal atrophy Bradykinetic (slowed movements) disorders can be caused by increased inhibitory basal ganglia outflow to the thalamus Blumenfeld, Neuroanatomy through Clinical Cases Rigidity • Increased resistance to passive movement of a limb • In spasticity, which results from upper motor neuron lesions, rigidity is velocity dependent. Resistive tone initially increases as the muscles of the limb are stretched, but it may then decrease, giving rise to clasp-knife rigidity in corticospinal disorders • In contrast, rigidity caused by basal ganglia disorders tends to be more continuous throughout attempts to bend the limb, and it has therefore been called plastic, or lead pipe rigidity Dystonia • The patient assumes abnormal, often distorted positions of the limbs, trunk, or face that are more sustained or slower than in athetosis • Focal dystonias include torticollis, which involves the neck muscles; blepharospasm, which involves the facial muscles around the eyes, and spasmodic dysphonia, which involves laryngeal muscles • Many cases of dystonia respond well to injection of botulinum toxin into the affected muscles Athetosis is characterized by twisting movements of the limbs, face and trunk that sometimes merge with faster choreic movements, giving rise to the term choreoathetosis Ballismus: Movements of the proximal limb muscles with a larger-amplitude, more rotatory or flinging quality than chorea • Hemiballismus (the most common type): there are unilateral flinging movements of the extremities contralateral to a lesion in the basal ganglia Chorea • Is applied to movement disorders characterized nearly continuous involuntary movements that have a fluid or jerky, constantly varying quality (dancing-like movements, they can't control). • In mild case, low-amplitude chorea may be mistaken for fidgeting or restless movements of extremities, face or trunk • Often incorporated into voluntary movements in an attempt to conceal their occurrence Major cause of chorea is Huntington’s disease (autosomal dominant neurodegenerative disorder). • Choreiform Gait Demonstration https://www.youtube.com/watch?v=PsFJkL3x10o