EXTRAPYRAMIDAL SYSTEMEXTRAPYRAMIDAL SYSTEMI.VelchevaI.Velcheva

University Hospital University Hospital ““St. Naum”St. Naum”

DEFINITIONDEFINITIONThe extrapyramidal system The extrapyramidal system

includes all motor gray includes all motor gray structures and pathways that structures and pathways that are not included in the pyramidal are not included in the pyramidal system. It is a set of subcortical system. It is a set of subcortical circuits and pathways and circuits and pathways and includes the includes the basal gangliabasal ganglia, , red red nucleus, brain stem reticular nucleus, brain stem reticular formation formation andand otherother brainstem brainstem nuclei.nuclei.

EXTRAPYRAMIDAL EXTRAPYRAMIDAL STRUCTURESSTRUCTURES

BASAL GANGLIA (5)BASAL GANGLIA (5)Corpus striatumCorpus striatum

NEOSTRIATUMNEOSTRIATUM Caudate nucleus(1)Caudate nucleus(1) Putamen(2)Putamen(2)

PALEOSTRIATUMPALEOSTRIATUM Globus pallidus(3)Globus pallidus(3) Substantia nigra(4)Substantia nigra(4) Subthalamic Subthalamic

nucleus(5)nucleus(5)Putamen + Globus Putamen + Globus

pallidus = Lenticular pallidus = Lenticular nucleusnucleus

EXTRAPYRAMIDAL STRUCTURESEXTRAPYRAMIDAL STRUCTURESCerebral cortexCerebral cortex

(premotor frontal, cingulate gyrus)(premotor frontal, cingulate gyrus)

Basal gangliaBasal gangliaThalamus Thalamus (ventral nuclei)(ventral nuclei)

Motor nuclei of the Motor nuclei of the brainstem: brainstem:

Red nucleus Red nucleus RF of pons and medulla oblongataRF of pons and medulla oblongata Pontine nucleiPontine nuclei Superior colliculi Superior colliculi Lateral vestibular nucleus Lateral vestibular nucleus Inferior oliveInferior olive CerebellumCerebellum

CONNECTIONS OF THE CONNECTIONS OF THE EXTRAPYRAMIDAL SYSTEMEXTRAPYRAMIDAL SYSTEM

Afferent connectionsAfferent connectionsCortical ipsilateral Cortical ipsilateral projections from frontal projections from frontal motor areas 4, 6amotor areas 4, 6aαα and and 6a6a fields to striatum fields to striatum (inhibitory)(inhibitory)Thalamic projections from Thalamic projections from the cenromedian nucleus the cenromedian nucleus (facilitatory) (facilitatory)

Connections between basal Connections between basal gangliaganglia

Caudate nucleus Caudate nucleus Substantia nigra Substantia nigra (GABA) (GABA) (inhibitory)(inhibitory)Substantia nigraSubstantia nigra Caudate Caudate nucleus nucleus (dopaminergic)(dopaminergic)

CONNECTIONS OF THE CONNECTIONS OF THE EXTRAPYRAMIDAL SYSTEMEXTRAPYRAMIDAL SYSTEM

Extrapyramidal Extrapyramidal circuitscircuits

Cerebral cortex Cerebral cortex Striatum Striatum Pallidum Pallidum Thalamus Thalamus Cerebral Cerebral cortex (4, 6aa, 6acortex (4, 6aa, 6a frontal fields)frontal fields)Striatum Striatum Pallidum Pallidum Thalamus Thalamus StriatumStriatumPallidum Pallidum Nucl. Nucl. Subthalamicus Subthalamicus PallidumPallidumStriatum Striatum Substantia Substantia nigra nigra Striatum Striatum

CONNECTIONS OF THE CONNECTIONS OF THE EXTRAPYRAMIDAL SYSTEMEXTRAPYRAMIDAL SYSTEM

Efferent connectionsEfferent connectionsStriatum Striatum Pallidum Pallidum Thalamus Thalamus Hypothalamus Hypothalamus Subthalamic nucleiSubthalamic nuclei

Subcortical Subcortical descending systemdescending system

Cortico – striate, - Cortico – striate, - rubral, - nigral, - rubral, - nigral, - reticular tracts to reticular tracts to brainstem and brainstem and spinal cord via spinal cord via descending chain of descending chain of neuronsneurons

NEUROTRANSMITTERSNEUROTRANSMITTERSStriatumStriatum – – acetylcholine + acetylcholine + dopamine, serotonin, GABAdopamine, serotonin, GABAAcetylcholine – dopamine balanceAcetylcholine – dopamine balanceGlobus pallidus – Globus pallidus – GABAGABABrainstem – Brainstem – NE, serotonin, NE, serotonin, enkephalin, glutamateenkephalin, glutamate

CLINICAL – PATHOLOGICAL CLINICAL – PATHOLOGICAL CORRELATIONS CORRELATIONS

Degeneration of the substantia Degeneration of the substantia nigra – nigra – ParkinsonismParkinsonismDestructive lesions of the Destructive lesions of the subthalamic nucleus – subthalamic nucleus – hemibalismhemibalismDegeneration in caudate nucl. Degeneration in caudate nucl. and putamen – and putamen – chorea, chorea, athetosisathetosis

CLINICAL – PATHOLOGICAL CLINICAL – PATHOLOGICAL CORRELATIONS CORRELATIONS

Degeneration of the Degeneration of the substantia nigra – substantia nigra – ParkinsonismParkinsonism

RigidityRigidity Hypokinesia Hypokinesia (slowness of (slowness of

voluntary movement)voluntary movement) Tremor Tremor (static, resting with (static, resting with

a frequency of 4-6Hz), a frequency of 4-6Hz), asymmetric, “pill-rolling” asymmetric, “pill-rolling” movementmovement

Abnormal gait and posture Abnormal gait and posture (flexed posture on standing (flexed posture on standing and walking)and walking)

CLINICAL – PATHOLOGICAL CLINICAL – PATHOLOGICAL CORRELATIONS CORRELATIONS

Degeneration in caudate Degeneration in caudate nucl. and putamen – nucl. and putamen – chorea chorea

Choreic involuntary movementsChoreic involuntary movements Muscular hypotoniaMuscular hypotonia Irregular gait and speech.Irregular gait and speech. Chorea dissapears during sleep.Chorea dissapears during sleep. Etiology: Sydenham`s (rheumatic) Etiology: Sydenham`s (rheumatic)

chorea,Huntington`s choreachorea,Huntington`s chorea

INVOLUNTARY MOVEMENTSINVOLUNTARY MOVEMENTS TremorTremor (rhythmic oscillatory movement, which(rhythmic oscillatory movement, which

occurs at rest, during maintenance of a particular posture, during occurs at rest, during maintenance of a particular posture, during movement)movement)

Static Static (resting) (resting) PosturalPostural ((physiologicalphysiological during sustained posture -8- during sustained posture -8- 12-20Hz, 12-20Hz, enhanced physiologicalenhanced physiological during fear or during fear or anxiety, anxiety, benign essential-benign essential- rhythmic, symmetric, rhythmic, symmetric, involves hands and head, familial)involves hands and head, familial) Intention tremor Intention tremor during activityduring activity

Tics Tics (sudden abrupt coordinated abnormal (sudden abrupt coordinated abnormal movements, repeated at short intervals)movements, repeated at short intervals) ((transient simple, chronic simple, transient simple, chronic simple, persistent simple or multiple, persistent simple or multiple, chronic multiple motor and vocal – Gilles de la chronic multiple motor and vocal – Gilles de la Tourette syndrome)Tourette syndrome)

INVOLUNTARY MOVEMENTSINVOLUNTARY MOVEMENTS

ChoreaChorea (rapid, irregular muscle jerks in different parts (rapid, irregular muscle jerks in different parts of the body, combined with muscular hypotonia)of the body, combined with muscular hypotonia)HemibalismHemibalism (violant unilateral involuntary jerks with (violant unilateral involuntary jerks with involvement of the proximal muscles)involvement of the proximal muscles)

Athetosis Athetosis (slow sinuous abnormal movements in (slow sinuous abnormal movements in the limbs)the limbs)

MyoclonusMyoclonus (sudden rapid twitchlike involuntary (sudden rapid twitchlike involuntary muscle contractions, which do not change the position of muscle contractions, which do not change the position of the affected body part)the affected body part)

(physiological, essential, epileptic)(physiological, essential, epileptic)

INVOLUNTARY MOVEMENTSINVOLUNTARY MOVEMENTSDystonia Dystonia (twisting repetitive movements of (twisting repetitive movements of axial and limb muscles, abnormal postures)axial and limb muscles, abnormal postures)

FocalFocal : : blepharospasm, spasmodic torticolos, blepharospasm, spasmodic torticolos, occupational cramps (writer`s cramp,violinist`s occupational cramps (writer`s cramp,violinist`s cramp ect.)cramp ect.)

Segmental Segmental – one leg and trunk– one leg and trunk MultifocalMultifocal – more than one limb– more than one limb GeneralizedGeneralized – all muscles of limbs and – all muscles of limbs and

trunktrunk HemidystoniaHemidystonia – unilateral limbs– unilateral limbs

INVOLUNTARY MOVEMENTSINVOLUNTARY MOVEMENTSChoreaChorea

INVOLUNTARY MOVEMENTSINVOLUNTARY MOVEMENTS

Dystonia Dystonia (generalized)(generalized)

INVOLUNTARY MOVEMENTSINVOLUNTARY MOVEMENTS

Dystonia Dystonia (focal)(focal)

INVOLUNTARY MOVEMENTSINVOLUNTARY MOVEMENTS

MyoclonusMyoclonus ((physiological, physiological, essential, epileptic)essential, epileptic)

MUSCLE TONEMUSCLE TONEA state of permanent muscleA state of permanent muscle

contraction in order to support posture (resistance of the contraction in order to support posture (resistance of the musclesmuscles

to passive movements).to passive movements).2 components: static (at rest) and dynamic (during stretch)2 components: static (at rest) and dynamic (during stretch)

Regulation of the muscle toneRegulation of the muscle toneThe normal muscle tone is defined by nonreflex (visco-elastic The normal muscle tone is defined by nonreflex (visco-elastic

properties of the muscles) and reflex mechanisms.properties of the muscles) and reflex mechanisms.Segmental mechanism – 2 reflex feedback systemsSegmental mechanism – 2 reflex feedback systems Stretched muscle at rest → muscle spindle → sensory fibers → Stretched muscle at rest → muscle spindle → sensory fibers →

alpha motor neurons (alpha motor neurons (αα fibers) → extrafusal muscles → contraction fibers) → extrafusal muscles → contraction (restoration of length)(restoration of length)

Active contraction (muscle tension) → Golgi organ → sensory fibers Active contraction (muscle tension) → Golgi organ → sensory fibers → alpha motor neurons (→ alpha motor neurons (ββ fibers) (inhibitory effect) fibers) (inhibitory effect)

Suprasegmental (reticulospinal) mechanismSuprasegmental (reticulospinal) mechanism Central impulses → gamma motoneurons (Central impulses → gamma motoneurons (γγ fibers) → intrafusal fibers) → intrafusal

muscle (increase of tension)muscle (increase of tension)

MUSCLE TONEMUSCLE TONERegulation of the muscle toneRegulation of the muscle tone

Segmental - stretch reflexSegmental - stretch reflex Suprasegmental (reticulospinal) Suprasegmental (reticulospinal)

MUSCLE TONEMUSCLE TONERegulation of the muscle toneRegulation of the muscle tone

Segmental - stretch reflexSegmental - stretch reflex

SYNDROMES OF DISORDERED SYNDROMES OF DISORDERED MUSCLE TONEMUSCLE TONE

Decreased Decreased muscle tone (muscle tone (hypotoniahypotonia, flaccidity), flaccidity) Indicates:Indicates: lower motor neuron lesion (efferent arm of the lower motor neuron lesion (efferent arm of the

reflex arc)reflex arc) Acute stage of pyramidal lesion (neural shock)Acute stage of pyramidal lesion (neural shock) Neostriatal lesion (chorea)Neostriatal lesion (chorea) Cerebellar lesionCerebellar lesion Acute stage of spinal cord lesion (spinal shock)Acute stage of spinal cord lesion (spinal shock) Primary muscle diseasesPrimary muscle diseases

SYNDROMES OF SYNDROMES OF DISORDERED MUSCLE TONEDISORDERED MUSCLE TONE

Increased Increased muscle tone muscle tone (hypertonia)(hypertonia) Spasticity Spasticity - - increased tone in certain muscle increased tone in certain muscle

groups (flexors of the arm and extensors of the groups (flexors of the arm and extensors of the legs) and increase of resistance linearly in relation legs) and increase of resistance linearly in relation to velocity of stretch.to velocity of stretch.

Spasticity indicates upper motor neuron lesions.Spasticity indicates upper motor neuron lesions. Rigidity Rigidity -- increased muscle tone with continuous increased muscle tone with continuous

“lead pipe rigidity”“lead pipe rigidity” or intermitent or intermitent “cogwheel “cogwheel rigidity”rigidity” muscle tension. muscle tension. Rigidity indicates extrapyramidal dysfunction.Rigidity indicates extrapyramidal dysfunction.