Extrapyramidal

Anatomy

• There are two motor system network causing involuntary actions:
  • Pyramidal tracts which directly innervates motor neurons of Spinal cord / Brainstem (Anterior / Ventral) horn cells / Certain cranial nerve nuclei
  • Extrapyramidal system (EPS) which Regulates / Indirect controls of Anterior/ Ventral horn cells.

• EPS is chiefly found in the reticular formation of the pons and medulla.
• EPS originate in brainstem, carrying motor fibers to the spinal cord.
• It is responsible for Unconscious / Reflexive / Responsive control of Reflexes / Muscle tone/ Balance / Posture / Locomotion / Complex movements
• EPS targets lower motor neurons in the spinal cord
• EPS are modulated by Nigrostriatal pathway, Basal ganglia, Cerebellum, Vestibular nuclei and sensory areas of cerebral cortex
• EPS modulate motor activity without directly innervating motor neurons

Function

Name	Explanation	Pathology
Balance	Postural tone adjustment	Ataxia
Reflexes	Preparation of predisposing tonic attitudes for involuntary movements Control of the reflexes that accompany the responses to affective and attentive situations (reactions)	Hypo Reflexia
Locomotion	Performing movements that make voluntary movements more natural and correct	Incoordination
Muscle tone	Control of automatic modifications of tone and movements	Rigidity
Complex movements	Control of the movements originally voluntary then become automatic through exercise and learning (e.g., in writing)	Awakwardness
	Inhibition of involuntary movements (Hyperkinesias), which are particularly evident in extrapyramidal diseases.	Tremor

Subdivisions

Functionally, the EPS can be subdivided into four tracts

• Vestibulospinal and Reticulospinal tracts (do not decussate, providing ipsilateral innervation).
• Rubrospinal and Tectospinal tracts (decussate, provide contralateral innervation)

Extrapyramidal symptoms

• Extrapyramidal symptoms are archetypically associated with Extrapyramidal tracts
• When such symptoms are caused by medications, they are also known as extrapyramidal side effects

Classification

• Acute dystonic reactions: Painful muscular spasms of neck, jaw, back, extremities, eyes, throat and tongue
  • Oculogyric crisis: An acute dystonic reaction that involves the prolonged involuntary upward deviation of eyes.

• Akathisia: A feeling of internal motor restlessness that presents as tension, nervousness, anxiety and an inability to sit still.
• Parkinsonism: Rigidity + Bradykinesia + Tremor + Tardive dyskinesia
• Pseudoparkinsonism: Rigidity, Bradykinesia, Tremor, Masked faces, Shuffling gait, Stooped posture, Sialorrhoea and Seborrhoea
  • Although Parkinson's disease is primarily a disease of the nigrostriatal pathway and not EPS, loss of dopaminergic neurons in the substantia nigra leads to dysregulation of EPS. Since this system regulates posture and skeletal muscle tone, a result is the characteristic bradykinesia of Parkinson's.
• Tardive dyskinesia: Involuntary muscle movements in the lower face and distal extremities; this can be a chronic condition associated with long-term use of antipsychotics.

Related disease

• Restless Leg Syndrome: Akathisia has very similar sensation
• Parkinson Disease
• RBD

Entities / Miasms

	JE	WNE	CJD	GSS	FFI
Ataxia	+++	+++	+++	+++	+++
Tremor	+++	+++	+	+++	+++
Bradykinesia / Parkinsonism	+++	+++	+++	+++	+++
Rigidity	+++	+++	+++

Note

• It seems that Extrapyramydal sign / Symptoms would be another COE, named EPS COE
• RLS, RBD, Parkinson disease are belonging to this COE