Functional Anatomy of the Spinal Cord

European Course in Neuroradiology Module 1 - Anatomy and Embryology 16th Cycle Module 1 Functional Anatomy of the Spinal Cord

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Johan Van Goethem

Spinal Cord Spinal nerves

• vertebral canal

• conus medullaris: adult Th12- L1 • ventral and dorsal roots • filum terminale

• cauda equina • intervertebral foramen

• gray matter: anterior and posterior horns • each pair (31) innervates a • white matter: anterior, lateral and posterior tracts body segment: dermatomes

• cervical (8 p.), thoracic (12 p.), lumbar (5 p.), sacral (5 p.) and coccygeal (1 p.)

Dorsal Root Ganglion Dorsal Root Ganglion

Elliot S. Krames et al 2014 Tiantian Guo et al 2019

Spinal cord anatomy Spinal cord anatomy

Source: Prometheus • 3 ascending pathways Anatomical atlas • 2 descending pathways Source: Wikipedia

40-year-old woman So what is this?

• gradual and uniform onset of • Lichtheim's disease • diminished pressure, vibration and touch sense • Lou Gehrig's disease • tingling and numbness of legs, arms and trunk that progressively worsens • Lyme disease • pain and temperature sense are normal • Devic’s disease • motor function is preserved, but slight ataxia And the answer is ... Let’s go back ...

• gradual and uniform onset of

• Lichtheim's disease • diminished pressure, vibration and touch sense • Lou Gehrig's disease • tingling and numbness of legs, arms and trunk that progressively worsens • Lyme disease • pain and temperature sense are normal • Devic’s disease • motor function is preserved, but slight ataxia

Spinothalamic tract Spinothalamic tract

• 3 neurons convey the information from periphery to the brain

• anterior • periphery - DRG • coarse touch and • Lissauer’s tract - tract cells

pressure • anterior:

• lateral • nucleus proprius (Rexed lamina IV & V)

• pain • lateral:

• temperature • substantia gelatinosa of Rolando (Rexed lamina II) • itch • cross the midline and run through the spinal cord - • sexual as the spinothalamic tract - and brainstem to synapse in the thalamus Source: Prometheus Anatomical atlas

Spinocerebellar tract Spinocerebellar tract

• 2 neurons convey the information from periphery to the brain

• periphery - DRG

• unconscious • 2nd order neurons in Clarke’s nucleus, dorsal nucleus or posterior thoracic nucleus (Rexed lamina VII) proprioception • posterior:

• walking • go to the cerebellum through the inferior cerebellar peduncle • running • ipsilateral

• biking • anterior: • ... • cross the midline • through the superior cerebellar peduncle and cross again in the cerebellum Source: Prometheus Anatomical atlas • “double cross” Fasciculus gracilis & cuneatus Fasciculus gracilis & cuneatus • posterior or dorsal columns • 3 neurons convey the information from periphery to the brain • tracts of Goll (cuneatus) and • periphery - DRG Burdach (gracilis) • dorsal column nuclei (nucleus gracilis and nucleus cuneatus) in the lower medulla (junction spinal cord / medulla • conscious oblongata) - internal arcuate fibers proprioception • fine touch, fine • continued and cross-over in the brainstem to form the medial lemniscus pressure and vibration • 2-point discrimination • relayed in the thalamus (3rd) to the postcentral gyrus Source: Prometheus Anatomical atlas

Dorsal columns Dorsal columns

Source: Prometheus Source: Prometheus Anatomical atlas Anatomical atlas

Fasciculus gracilis & cuneatus Subacute combined degeneration

• degeneration of the posterior (and lateral) columns as a result of vitamin B12 deficiency • dietary deficiency of B12, malabsorption of B12 in the terminal ileum, lack of intrinsic factor, inactivation by N20 So what is this? 52-year-old woman

• unable to move her legs after abdominal procedure •• Lichtheim'ssubacute combined disease degeneration • areflexic in the lower extremities with negative •• Louamyotrophic Gehrig's diseaselateral sclerosis Babinski testing bilaterally •• Lymeneuroborreliosis disease •• Devic’sneuromyelitis disease optica • sensory level to pain and temperature extended up to Th10

• other intact

Corticospinal tract Corticospinal tract

• • part of the pyramidal tract 2 - 3 neurons convey the information from (together with the the brain to the periphery corticobulbar) • 30% precentral gyrus, 30% premotor, • conscious motor 40% other • lateral • directly to alpha motor neurons or • 80-90% through interneurons • limbs • 90% cross the midline in the • anterior medulla (limbs) • 10-20% • 10% stays ipsilateral and crosses at • neck, shoulders the level of the spinal nerve Source: Prometheus Anatomical atlas

Extrapyramidal tracts Back to our case

• • unconscious motor lesions of pyramid tracts or extrapyramid tracts are always combined due to their close proximity • automated • mediation and regulation • lesions of these tracts may cause Babinski sign • lateral • • rubrospinalis no reflex = no α-motorneuron function • arm and hands fine motor • medial • reticulospinalis anterior, tectospinalis, vestibulospinalis

Source: Prometheus • legs and trunk Source: Prometheus Anatomical atlas Anatomical atlas Back to our case Back to our case

Source: Prometheus Source: Prometheus Anatomical atlas Anatomical atlas

Spinal cord infarction 9-year-old girl • acute flaccid paresis • AFP is the most common sign of acute polio, and used for surveillance during polio outbreaks

Case provided by Prof. Thurnher

Grey matter Anatomy revisited

• Rexed laminae, defined by cellular structure, similar to Brodman

Source: Wikipedia Source: Wikipedia What is all the other stuff? What is all the other stuff?

• interneuron coordination (reflexes, proprioception)

Source: Prometheus Anatomical atlas

• autonomic nervous system • mostly diffuse

Conclusion

• spinal cord anatomy revisited

• 3 main ascending pathways

• 2 main groups of ascending pathways

• diagnosis through

• knowledge of the anatomy spinal cord

• high resolution MR of the spinal cord

• neurologic signs and symptoms