Cerebellar System Disorders PDF

02-Nov-23 Cerebellar system disordes Dr. Mahmoud ElSayed Midan PhD. Lecturer of PT for Neurology 1 Cerebellar system: The main...

02-Nov-23 Cerebellar system disordes Dr. Mahmoud ElSayed Midan PhD. Lecturer of PT for Neurology 1 Cerebellar system: The main body organ concerned with coordination is the cerebellum. 2 1  02-Nov-23 Cerebellar system: depends on feedback from: vestibular system (sometimes called central proprioception) sensory system mainly deep proprioceptive sensation vision can partially substitute for sensory disturbances. motor efference copy. input from the motor cortex 3 According to output: cerebellum functionally has three unite A. Archicerebellum (vestibular cerebellum): the flocculonodular lobe. output connected to the vestibular nuclei function related to balance and eye movement. B. Paleocerebellum (spinocerebellum): the vermis and adjoining part of anterior lobe. It has output connected to spinal cord its function related to postural tone and assist in coordination between limb muscles. C. Neocerebellum (cerebral- cerebellum): The large part of posterior lobe of cerebellar output connected to motor cortex function related to planning, timing, and coordination of movement. 4 2  02-Nov-23 The cerebellum act through two main systems A) feed backward (closed loop system): Cerebellum uses the ongoing sensory input Compare it to the desired motor action (efference copy) Give corrective output indirectly connection extrapyramidal to the cortex system 5 The cerebellum act through two main systems A) feed backward (closed loop system): It is effective in low skilled movements. responding to postural perturbations. It also occurs early during learning of any new skill. 6 3  02-Nov-23 The cerebellum act through two main systems B) feed forward (open loop system): permit faster, smother and more effective motor responses. Cerebellum used the previous learned motor activity Considering instantaneous sensory input Assist in planning and coordination of executed motor task 7 Cerebellar function disturbances Disturbance in the cerebellum itself or any of its information systems lead to failure of its function defined as ataxia. 8 4  02-Nov-23 Cerebellar ataxia Cerebellar ataxia referred to incoordination movement due to damage to the cerebellum or its peduncles. 9 Cerebellar ataxia: A) Archicerebellar syndrome (truncal Ataxia) Damage related to midline of the cerebellum. Affect mainly the functions related to equilibrium characterized by: Disturbed balance (truncal ataxia). Wide base of support. Wide based or drunken gait. 10 5  02-Nov-23 Cerebellar ataxia: B) Neocerebellar syndrome (Limb Ataxia) Limb ataxia. Damage related to cerebellar hemispheres head nodding. (cerebral cerebellum). trunk titubation. Nystagmus: fixation nystagmus. Fast phase Affect mainly the functions related to to the direction of fixation. coordination of fine motor skills. Staccato speech: explosive interrupted. Asthenia: genialized weakness or easily fatigability. Deviation of gait toward the affected side Zigzag gait in bilateral. Impaired planning and learning. 11 Cerebellar ataxia: B) Neocerebellar syndrome (Limb Ataxia) 1. Dysmetria (Lack of accuracy): the patients have difficulties to reach to specific point in space. With activity there is hypermetria (passing target) or hypometria (not reaching the target). Lack of accuracy also can be referring for timing problems. 2. Decomposition of movement: the movement lose its smoothness and interrupted into several components and sometimes with wrong component. It also called dyssynergia. 3. Lack of proximal stability (limb holding): the patients have difficulties to coordinate activation of proximal muscles to provide stability together with distal mobility. 12 6  02-Nov-23 Cerebellar ataxia: B) Neocerebellar syndrome (Limb Ataxia) 4. Dysdiadochokinesia: difficulties doing reciprocal alternating movements, it is done with slowness arrhythmic pattern. In severe cases the is loss of ability to do reciprocal movement and so called “adiadochokinesia’’ 13 Cerebellar ataxia: B) Neocerebellar syndrome (Limb Ataxia) 5. Dynamic (intentional) tremor: tremor during movement characterises the ataxic patients. As lake of coordination between antagonistic muscle groups and as a part of volitional correction. Sometimes it is most prominent at the end of movement as it reaches the target and is called “terminal tremor”. 6. Rebound phenomenon: Inability to stop activation or control over suddenly unloaded movement. eg: if we forcefully resist elbow flexion and suddenly release this resistance the elbow is taken into forceful flexion and even hurt the patient. 14 7  02-Nov-23 Causes of cerebellar ataxia: Hereditary: Friedreich’s ataxia Marie’s ataxia Symptomatic: Congenital as in Arnold Chiari malformation. Vascular infarction. Infective as encephalitis or cerebellar abscess. Neoplastic tumours. Toxic as alcohol and barbiturates. Demyelination as MS. Metabolic as cortical cerebellar degeneration in para neoplastic syndrome. Idiopathic: delayed cortical cerebellar degeneration in old age. 15 Sensory ataxia Ataxic feature that is caused by damage related to sensory information to the cerebellum. Visual input could partially substitute for sensory loss. In these patients, activities with open eye is much better than closed eye In mild cases ataxia may be fully unrecognisable with eye tracking. 16 8  02-Nov-23 Sensory ataxia: Sensory ataxia characterized by: Hyporeflexia or areflexia and hypotonia caused by damage of afferent part of reflex arch. Loss of deep sensation along with fine discriminative touch sensation specially in hand and foot sole which are important for fine hand activities and balance. Balance disturbance with closing eye (Romberg sign +ve) and the patient tend to take wide BOS. Stamping gait: it is a characteristic gait for sensory ataxia patients in which the patient hit the ground with each step. There are several presented causes for this pattern of gait, 17 Stamping gait: o Lack of appropriate motor control let the muscular activity unbraced and inaccurate. o Hitting the floor hardly increases sensory input to the CNS. o Alternating use of sound as feedback instead of deep proprioceptive input. 18 9  02-Nov-23 19 Sensory ataxia Sensory disturbances and deprivation may occur at any level: Peripheral nerves affection as peripheral neuropathy. Dorsal root ganglions as in tabs dorsalis. Posterior column of spinal cord as in MS or SCI. Medial lemniscus at brainstem as in infarctions. 20 10  02-Nov-23 Vestibular ataxia Ataxic feature that is caused by damage related to vestibular information to the cerebellum. Visual input couldn’t substitute for vestibular affection. Disturbances in balance and equilibrium occur either with open or closed eye. 21 vestibular ataxia characterized by: Balance disturbance with opened or closed eye. Patient tend to take wide BOS with increased postural sway or in ability to maintain upright posture. Vertigo: patient complain of sense of rotation of body or surroundings. neurovegetative signs (nausea and vomiting). Nystagmus: vestibular disturbances accompanied by non-fixational nystagmus. Reflexes and tone are normal. Superficial and deep sensation are normal. Gait: patient tend to take wide base in mild cases in severe it is characterised by clumsy zigzag gait that is called drunken gait. 22 11  02-Nov-23 Vertigo 23 Vestibular affection may be: a) Central: affection of vestibular nuclei in the brain system as in infarction. a) Peripheral: affection of 8th CN as in vestibular neuritis affection of the vestibule itself as in BPPV or menier’s disease. 24 12  02-Nov-23 Vestibular ataxia 25 13