ICP CSF Spinal Cord Anatomy Cord Transection. Alicia A C Waite March 2nd, 2017

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1 ICP CSF Spinal Cord Anatomy Cord Transection Alicia A C Waite March 2nd, 2017

2 Monro-Kellie doctrine Intracranial volume = brain volume (85%) + blood volume (10%) + CSF volume (5%) Brain parenchyma Skull CSF Arterial / venous blood Excessively high intracranial pressure can lead to brain herniation

3 ICP - Normal ICP: 5-15mmHg - Main intracranial volume buffer is CSF and then blood. - Compensatory mechanisms can maintain normal ICP for volume changes less than about 120ml. - Symptoms and signs of raised ICP include headache, nausea, vomiting, ocular palsies, altered conscious level and papilloedema. - Prolonged high ICP can lead to Cushing s triad: - Hypertension (increased systolic BP with a widened pulse pressure) - Bradycardia - Abnormal respiration

4 CSF - Total volume ~130ml - 30ml in ventricular system - 25ml in subarachnoid space intracranially - 75ml in subarachnoid space around spinal cord - Rate of formation: ~0.35ml/hr (500ml/day). (Not affected by ICP) - Total volume replaced every 8-12 hours - CSF secreted by epithelial cells in the choroid plexus (mainly in lateral ventricle) CSF mainly drains back into the venous system via arachnoid villi

5 CSF CSF Compared to plasma Appearance clear, colourless ph 7.32 lower Osmolality 290mosm/kgH2O Protein 0.3g/L lower Glucose 4.8mmol/L lower pco2 6.6kPa higher Chloride 120 higher

6 CSF Blood-CSF barrier is formed by tight junctions between choroid plexus epithelial cells. Choroid plexus is found in all four cerebral ventricles. CSF flows from lateral ventricles through the interventricular foramen of Monro into the third ventricle. It passes via the narrow cerebral aqueduct of Sylvius into the fourth ventricle. It leaves the ventricular system in the medulla, through the midline median aperture (foramen of Magendie) and paired lateral apertures (foramina of Luschka) CSF mainly drains back in the venous channels via arachnoid villi

Choroid plexus An illustration of the choroid plexus in the lateral ventricle showing choroid plexus (CP) epithelial cells resting on a basement membrane.

7 Choroid plexus An illustration of the choroid plexus in the lateral ventricle showing choroid plexus (CP) epithelial cells resting on a basement membrane. Journal of Neuropathology and Experimental Neurology, March

8 CSF

9 Spinal Cord Anatomy Cord Transection

16 Spinal cord anatomy - Names of tracts: from origin to destination - spinocerebellar => from the spine to the cerebellum - corticospinal => from the cortex to the spine - Role of tracts / columns - dorsal column-medial lemniscus => fine touch, vibration, proprioception - spinothalamic => pain, temperature, crude touch - spinocerebellar / spino-olivary=> proprioception - corticospinal / corticobulbar => motor - extra-pyramidal (rubrospinal / recticulospinal / vestibulospinal / tectospinal) => modulate motor activity - Decussation: - spinothalamic crosses midline at spinal level - dorsal column / corticospinal crosses in medulla - spinocerebellar - mixed: some tracts cross midline, others don t -> all eventually end on ipsilateral side. - exta-pyramidal - mixed: some tracts cross midline.

17 Topography

18 Topography

19 Blood supply to the spinal cord

21 Spinal cord injuries - Complete injury = no spared motor or sensory function below in the injury level - Incomplete injury = injury iwth some preserved motor or sensory function below the level injury Complete injury accounts for 47% of spinal cord injuries. Incomplete tetraplegia - 34% Incomplete paraplegia - 17%

22 Incomplete spinal cord injuries Anterior cord syndrome Posterior cord syndrome Brown Sequard syndrome Central cord syndrome

23 Anterior cord syndrome - Motor dysfunction with sensory deficit below level of spinal cord injury. - Pathophysiology: - direct compression of anterior spinal cord - anterior spinal artery injury - Worst prognosis amongst incomplete spinal cord injuries - can mimic complete cord injury % chance of motor recovery 95% of spinal cord infarction affects anterior aspect.

24 Posterior cord syndrome - Very rare - Loss of proprioception and vibration sense. - Motor, pain and light touch pathways preserved.

Brown Sequard Syndrome - Complete cord hemitransection - DCML: Ispilateral loss of fine touch, proprioception, vibration - Spinothalamic: Contralateral loss of pain / temperature sense -

25 Brown Sequard Syndrome - Complete cord hemitransection - DCML: Ispilateral loss of fine touch, proprioception, vibration - Spinothalamic: Contralateral loss of pain / temperature sense - Corticopspinal: Ipsilateral hemiparesis - Seen with penetrating trauma - Excellent prognosis -> 99% ambulatory at final follow up

Central cord syndrome http://www.orthobullets.com/spine/2008/incomplete-spinal-cord-injuries?

26 Central cord syndrome - Most common incomplete spinal cord injury - Often in elderly patients with minor extension injury - Pathophysiology: central cord oedema and spinal cord compression - Upper extremities and hands preferentially affected - also recover last. - Good prognosis but full functional recovery is rare - often have permanently clumsy hands

27 1. Cerebrospinal fluid a - has a composition almost identical to plasma b is produced by the choroid plexus c circulates from the subarachnoid space into the cerebral ventricles d is absorbed into the arachnoid villi e is produced at a rate of 150ml/day 2. Cerebral autoregulation a is shifted to the left in systemic hypertension b is generally expressed as the relationship between cerebral blood flow and systolic blood pressure c attempts to keep cerebral blood flow constant at normal blood pressures d is rarely impaired following a head injury e is most likely explained by the myogenic theory 3. Cerebral blood flow a averages 20ml/100g/min b is dependent on the mean arterial pressure and the intracranial pressure c increases by 2-4% for each mmhg increase in PCO2 d usually matches cerebral metabolism (flow-metabolism coupling) e cannot be measured using the Kety-Schmidt equation 4. Intracranial pressure (ICP) a is usually between 0 and 10mmHg b if raised causes hypertension and tachycardia c can be reduced by improving the cerebral perfusion pressure d and its relationship with intracranial volume is shown on the elastance curve e is increased when a patient is put head-down MCQ answers: 1. FTFTF // 2. FFTFT // 3. FTTTF // 4. FFTTT

28 1. The spinal cord a - occupies the lumbar cistern b has 12 cervical segments c ends at the conus medullaris d has no arachnoid membrane e contains the cell bodies of post ganglionic sympathetic efferent neurons 2. Which of the following tracts crosses at the spinal cord level of entry? a lateral corticospinal b anterior spinothalamic c anterior spinocerebellar d posterior spinocerebellar e anterior corticospinal 3. The blood supply for the cortiocspinal tract is derived from the a vertebral arteries b posterior spinal arteries c anterior spinal artery d basilar artery e posterior communicating artery 4. In the laminar somatotopic organisation of the dorsal columns, the most lateral fibres represent: a sacral region b thoracic region c lumbar region d cervical region e coccygeal region SBA answers: DBCD

29 References FRCA worksheets - Cerebral Blood Flow and Intracranial Pressure %20I.pdf Anaesthesia UK. Neuroscience Online, McGovern Medical School. neuroscience/s2/chapter03.html Ortho Bullets.

The Spinal Cord. The Nervous System. The Spinal Cord. The Spinal Cord 1/2/2016. Continuation of CNS inferior to foramen magnum.

The Spinal Cord. The Nervous System. The Spinal Cord. The Spinal Cord 1/2/2016. Continuation of CNS inferior to foramen magnum. The Nervous System Spinal Cord Continuation of CNS inferior to foramen magnum Simpler than the brain Conducts impulses to and from brain Two way conduction pathway Reflex actions Passes through vertebral