ANATOMY - DR.SANJIVANI ANATOMY - DR.SANJIVANI

SPINAL ANAES - DR PALLAVISPINAL ANAES - DR PALLAVI

EPIDURAL ANAES - DR.TANZEEM EPIDURAL ANAES - DR.TANZEEM

INTRODUCTIONINTRODUCTION

Spinal & Epidural Anesthesia Techniques are blind procedures. Spinal & Epidural Anesthesia Techniques are blind procedures. Even in expert hands chances of failure are high. Knowledge of Even in expert hands chances of failure are high. Knowledge of Anatomy increases success rate.Anatomy increases success rate.

Neurovascular structure eg.spinal cord is closely associated with Neurovascular structure eg.spinal cord is closely associated with epidural space. So knowing anatomy & correct technique can epidural space. So knowing anatomy & correct technique can reduce devasting complications.reduce devasting complications.

Real boon to patients with medical derangement & conditions Real boon to patients with medical derangement & conditions where GA is contraindicated. where GA is contraindicated.

COMPONENTSCOMPONENTS

Vertebral columnVertebral column: forms a canal: forms a canal for spinal cord & protect it.for spinal cord & protect it. 33 vertebrae:33 vertebrae: Cervical - 7Cervical - 7 Thoracic – 12Thoracic – 12 Lumbar – 5 (4% cases – 6)Lumbar – 5 (4% cases – 6) Sacral – 5 Sacral – 5 CoccyxCoccyx

AA Typical vertebraeTypical vertebrae: : 1) Body1) Body 2) Arch 2) Arch 3) Processes: 3) Processes: 2 transverse processes.2 transverse processes. 1 spinous process1 spinous process 4 articular pr. 4 articular pr.

Gaps:Gaps:

1) 1) Lateral intervertebral gap: Lateral intervertebral gap: - gap between upper & lower pedicles.- gap between upper & lower pedicles.

- Forms intervertebral foramen from - Forms intervertebral foramen from which nerve roots emerges.which nerve roots emerges.

2) 2) Posterior interlaminar gap:Posterior interlaminar gap:

- formed by central part of lamina- formed by central part of lamina which is relatively shallow.which is relatively shallow.

- Site of epidural & spinal punture.- Site of epidural & spinal punture.

Ligaments:Ligaments: Supports vertebral column & provides stability.Supports vertebral column & provides stability.

1) 1) Supraspinous: Supraspinous:

- Connecting apices of spines - Connecting apices of spines

- extent C-7 -- sacrum.- extent C-7 -- sacrum.

- Above C-7 blends with- Above C-7 blends with

ligamentum nuchae ligamentum nuchae

in neck & attach to in neck & attach to

external occipetal external occipetal

protuberance of skull. protuberance of skull.

2) 2) Interspinous ligament:Interspinous ligament:

- Connect adjacent spines – upper - Connect adjacent spines – upper

& lower spine.& lower spine.

3) 3) Ligamentum flavum: Ligamentum flavum:

- most important ligament.- most important ligament.

- extend between lamina from the anterior- extend between lamina from the anterior inferior surface of the upper laminainferior surface of the upper lamina downward to the anterior superiordownward to the anterior superior surface of the lower lamina.surface of the lower lamina.

- extends from foramen magnum – sacral- extends from foramen magnum – sacral hiatus.hiatus.

- distance from skin – Ligamentum Flavum – 3 – 8 cm. - distance from skin – Ligamentum Flavum – 3 – 8 cm.

- cephalad – caudal thickness – 1.5 – 6 mm.- cephalad – caudal thickness – 1.5 – 6 mm.

4) 4) Anterior & posterior longitudinal ligamentAnterior & posterior longitudinal ligament

joining body of vertebrae anterior & posteriorly.joining body of vertebrae anterior & posteriorly.

IMPIMP: : Needle inserted in spinal / Epidural A penetrateNeedle inserted in spinal / Epidural A penetrate

1)1) Midline approachMidline approach : : SkinSkin

Subcutaneous tissue,Subcutaneous tissue, Supraspinous ligament Supraspinous ligament Interspinous lig.Interspinous lig. Lig. Flavum – 1st clickLig. Flavum – 1st click.. Epidural spaceEpidural space Dura – 2 nd click.Dura – 2 nd click. Subdural space.Subdural space. Arachnoid matterArachnoid matter Subarachanoid spaceSubarachanoid space

2)2) Paramedian approach:Paramedian approach: Little resistance until Lig. Flavum.Little resistance until Lig. Flavum. Needle passes lat. to supraspinous Needle passes lat. to supraspinous & interspinous lig and penetrates & interspinous lig and penetrates Lig. Flavum & dura at midline.Lig. Flavum & dura at midline.

Meninges of spinal cord: Meninges of spinal cord:

1) Dura matter.1) Dura matter. 2) Arachnoid matter2) Arachnoid matter 3) Pia matter—firmly attached to spinal cord.3) Pia matter—firmly attached to spinal cord.

Dura matterDura matter:: form sac around cord form sac around cord

- Continuation of meningeal inner layer of cranial dura- Continuation of meningeal inner layer of cranial dura matter. matter. -extends from foramen magnum to S2 vertebrae. -extends from foramen magnum to S2 vertebrae.

Subdural space:Subdural space:

-contains-contains small amount of serous fluid.small amount of serous fluid. -accidental injection of drug -failed spinal A during SAB.-accidental injection of drug -failed spinal A during SAB. -total spinal A if epidural drug -total spinal A if epidural drug

Arachnoid matterArachnoid matter : : delicate non-vascular structuredelicate non-vascular structure..

SA space :SA space :

- potential space lined externally - potential space lined externally by – arachnoid matter by – arachnoid matter - internally by pia matter close to spinal cord.- internally by pia matter close to spinal cord. - contents : CSF- contents : CSF

- spinal nerve - spinal nerve -denticulate ligament-denticulate ligament -cobweb trabaculae-cobweb trabaculae - shape : annular (3mm) – Cx , thoraxic region.- shape : annular (3mm) – Cx , thoraxic region. circular – lumbarcircular – lumbar

Pia matter:Pia matter: -highly vascular thin membrane covering cord, -highly vascular thin membrane covering cord, terminates at phylum terminalae.terminates at phylum terminalae. -gives lat. extension called denticulate lig.-gives lat. extension called denticulate lig.

Denticulate Ligament :Denticulate Ligament :

- folds of pia matter.- folds of pia matter.

- Struts holding spinal cord.- Struts holding spinal cord.

- attach to ant. & post. roots & fused with arachnoid - attach to ant. & post. roots & fused with arachnoid

matter & dura.matter & dura.

- contains elastic fibers – provides elasticity to & - contains elastic fibers – provides elasticity to &

acts as strutsacts as struts

- can leads to patchy or unilateral anaesthesia.- can leads to patchy or unilateral anaesthesia.

Anatomic curves of spineAnatomic curves of spine

supine position supine position

highest pt. – 3rd lumber.highest pt. – 3rd lumber.

low pt. – 5th thoraxiclow pt. – 5th thoraxic

IMP IMP - - deposition ofdeposition of

hypo / iso / hyperbarichypo / iso / hyperbaric

solution in SAB.solution in SAB.

Normal curves of spineNormal curves of spine

-double ‘S’ shape..-double ‘S’ shape..

Abnormal curves :Abnormal curves :

- kyphosis : exaggerated AP thoraxic curves- kyphosis : exaggerated AP thoraxic curves

- lordosis : lumber curves – physiological lordosis seen - lordosis : lumber curves – physiological lordosis seen

3rd trimester of pregnancy.3rd trimester of pregnancy.

- scoliosis : lateral curvature.- scoliosis : lateral curvature.

IMP :IMP : abn. curvature of spine can cause spinal or epidural Aabn. curvature of spine can cause spinal or epidural A

difficult or in extreme cases impossible.difficult or in extreme cases impossible.

so in PAC while doing spine examination noting curvatureso in PAC while doing spine examination noting curvature

of spine is very important.of spine is very important.

Developmental anatomy of spinal cord: Developmental anatomy of spinal cord:

Spinal cord develops from caudal part of neural tube & extendsSpinal cord develops from caudal part of neural tube & extends

throughout the length of vertebral column during fetal life. throughout the length of vertebral column during fetal life.

Rapid growth of vertebral column causes spinal cord to lag behind. Rapid growth of vertebral column causes spinal cord to lag behind.

so spinal cord ends at higher level.so spinal cord ends at higher level.

Meningeal covering also ends at higher level because they cannotMeningeal covering also ends at higher level because they cannot

keep pace with slow growth of spinal cord or fast growth of keep pace with slow growth of spinal cord or fast growth of

vertebral column.vertebral column.

Age Lower end of SC Dural sac Age Lower end of SC Dural sac

6th month of fetal life S1 S56th month of fetal life S1 S5 Birth L3 S3Birth L3 S3 1st year L2 (28%-L3) S2 (1st year L2 (28%-L3) S2 (no LP above no LP above

L4L4)) Adult ( upper border of L2 or S2Adult ( upper border of L2 or S2 lower border of L1) – 90% lower border of L1) – 90%

This differential growth of spinal cord & This differential growth of spinal cord & vertebral column causes development vertebral column causes development of caudal canal & epidural space.of caudal canal & epidural space.

..

IMP:IMP: Lumber punctureLumber puncture In children NEVER ABOVE L4.In children NEVER ABOVE L4. Adult preferably L3 – L4 interspace,Adult preferably L3 – L4 interspace, In 10% population cord extends upIn 10% population cord extends up to lower border of L2. So avoidto lower border of L2. So avoid using L2 – L3 interspaceusing L2 – L3 interspace

Spinal nerves:Spinal nerves:

31 pairs of nerves:31 pairs of nerves:

Cx -- 8Cx -- 8 Thoracic -- 12Thoracic -- 12 Lumber – 5 Lumber – 5 Sacral -- 5Sacral -- 5 Coccyx – 1Coccyx – 1

Each nerve anterior roots –motor intervertebralEach nerve anterior roots –motor intervertebral foramen foramen Posterior roots – sensoryPosterior roots – sensoryIMP :IMP : passage of nerve through intervertebral foramen is the site of action of passage of nerve through intervertebral foramen is the site of action of

drug given in epidural anaesthesiadrug given in epidural anaesthesia..

Each nerve supplies –Each nerve supplies –

body wallbody wall

Vertebral muscles dermatomeVertebral muscles dermatome

Overlying skinOverlying skin

And communicates with sympathetic chain And communicates with sympathetic chain

through white and grey rami. through white and grey rami.

spinal nerve roots are not uniform inspinal nerve roots are not uniform in

size or structure bilaterally.size or structure bilaterally.

IMPIMP-Large inter individual variability – -Large inter individual variability –

differences in level of Neuroaxial differences in level of Neuroaxial

blocked quality even same amount blocked quality even same amount

of drug is given.of drug is given.

Topographic line of Tuffier:Topographic line of Tuffier:

Line across back, between crest of illia passes over spine of L4 in uprightLine across back, between crest of illia passes over spine of L4 in upright

position.position.

In lying down position passes through L4 – L5.In lying down position passes through L4 – L5.

IMP:IMP: acts as landmark on back for identification & numbering of interspace acts as landmark on back for identification & numbering of interspace

between spinous process of vertebrae.between spinous process of vertebrae.

Blood supply of spinal cord: Blood supply of spinal cord:

Anterior spinal artery:Anterior spinal artery:

- Formed at foramen magnum by a branch from terminal- Formed at foramen magnum by a branch from terminal portion of each vertebral A. portion of each vertebral A.

- Runs along Anterior median fissure & descends whole length. - Runs along Anterior median fissure & descends whole length.

- Supplies anterior 2/3 of spinal cord.- Supplies anterior 2/3 of spinal cord.

Posterior spinal artery:Posterior spinal artery:

- 4 longitudinally running vessels -2 on each side - 4 longitudinally running vessels -2 on each side

- Originates at base of brain from vertebral A or Posterior inferior - Originates at base of brain from vertebral A or Posterior inferior cerebellar A.cerebellar A.

- Supplies – posterior 1/3 of spinal cord - Supplies – posterior 1/3 of spinal cord

Reinforcement:Reinforcement:

- Spinal radicular branches from local segmental A- Spinal radicular branches from local segmental A (derived from aorta)(derived from aorta) -vertebral -vertebral

-Ascending cervical-Ascending cervical -Posterior intercostal-Posterior intercostal -Spinal lumbar-Spinal lumbar -Lateral sacral A-Lateral sacral A

- Forms anastomoses with anterior & posterior spinal A.- Forms anastomoses with anterior & posterior spinal A.

- Posterior radicular br. are larger & numerous.- Posterior radicular br. are larger & numerous.

- Large radicular A. are found at upper thoraxic (T1) &- Large radicular A. are found at upper thoraxic (T1) &

upper lumber L1.upper lumber L1.

- Most of radicular br. are small & terminates in ventral N- Most of radicular br. are small & terminates in ventral N

root or in plexus of pia matter around cord. root or in plexus of pia matter around cord.

Arteria radicularis magna (A of Adam kewiz):Arteria radicularis magna (A of Adam kewiz):

Large ant. radicular A.Large ant. radicular A.

Derived directly from thoraxic Derived directly from thoraxic

aorta mostly on left side.aorta mostly on left side.

Provide rich reinforcement to Provide rich reinforcement to

ant. Spinal A. in Lumber area.ant. Spinal A. in Lumber area.

Responsible for major blood Responsible for major blood

supply of lower 2/3 of supply of lower 2/3 of

spinal cord in 50% population.spinal cord in 50% population.

Peculiarity of blood supply of spinal cord:Peculiarity of blood supply of spinal cord:

Each cm of spinal cord receives 5-8 br. WhichEach cm of spinal cord receives 5-8 br. Which penetrates substance of cord.penetrates substance of cord.

No anastomoses seen in this penetrating br. No anastomoses seen in this penetrating br. so they act as end vessels.so they act as end vessels. There is no anastomoses between ant. &There is no anastomoses between ant. & post. Spinal A.post. Spinal A.

However overlapping of territories seenHowever overlapping of territories seen between ant. & post. spinal A. between ant. & post. spinal A. IMP:IMP:

Delicate System because of endDelicate System because of end artery structure.artery structure.

Quite vulnerable to minor trauma &Quite vulnerable to minor trauma & vasoconstrictor drugs.vasoconstrictor drugs.

Ant. spinal A syndrome.Ant. spinal A syndrome.

Cauda equina syndrome.Cauda equina syndrome.

Veins of spinal cord Veins of spinal cord

Six veins – longitudinal plexiform Six veins – longitudinal plexiform

Median Median

4 lateral longitudinal veins – communicates with 4 lateral longitudinal veins – communicates with

int.vertebral pr. ext. vertebral plexusint.vertebral pr. ext. vertebral plexus

– – K/a Batson plexus which is valveless. K/a Batson plexus which is valveless.

Veins draining spinal cord, vertebral column & meninges.Veins draining spinal cord, vertebral column & meninges.

Forms:Forms:

External plexusExternal plexus both are valveless & anastomoses freely both are valveless & anastomoses freely

with each other.with each other.

Internal plexusInternal plexus

Veins of vertebral column constitute venous system parallel to mainVeins of vertebral column constitute venous system parallel to main

caval system. caval system.

Extensive communication thr. SegmentsExtensive communication thr. Segments

Increase pressure in abdomen or thorax increases blood flow thr.Increase pressure in abdomen or thorax increases blood flow thr.

vertebral system rather than caval system.vertebral system rather than caval system.

IMP: IMP:

In condition with increase abd pressure e.g. Pregnancy epidural vein In condition with increase abd pressure e.g. Pregnancy epidural vein

tortuous causing decrease in subarachanoid space – reduced tortuous causing decrease in subarachanoid space – reduced

quantity of drug required for SAB.quantity of drug required for SAB.

More absorption of drug by epidural veins so systemic toxicity of More absorption of drug by epidural veins so systemic toxicity of

drugs achieves earlier than other pts.drugs achieves earlier than other pts.

Anatomy:Anatomy:

- Space between periosteum & dura. - Space between periosteum & dura.

- Circular space surrounding dura.- Circular space surrounding dura.

- Extends from foramen magnum - Extends from foramen magnum to coccyx.to coccyx.

- Cranially bounded at foramen - Cranially bounded at foramen magnum where periosteal magnum where periosteal layer fuses with dural layer &layer fuses with dural layer & lower caudal limit is by lower caudal limit is by sacrococcaygel membrane.sacrococcaygel membrane.

- Anteriorly – post. Long. Ligament.- Anteriorly – post. Long. Ligament.

- Posteriorly. – Lig. Flavum.- Posteriorly. – Lig. Flavum.

- Laterally. – pedicles and - Laterally. – pedicles and intervertebral foramen.intervertebral foramen.

..

Needle in epidural space penetratesNeedle in epidural space penetrates: : Skin & subcutaneous tissue.Skin & subcutaneous tissue.Supraspinous ligament.Supraspinous ligament.Interspinous ligament.Interspinous ligament.Ligamentum Flavum.Ligamentum Flavum.

Width:Width: Semi / half moon shape.Semi / half moon shape.

1 –1. 5 mm (C1- C2 level.)1 –1. 5 mm (C1- C2 level.)1 – 6 mm (sacral.)1 – 6 mm (sacral.)distance from skin-Adult male – 4.7 cm( at L3 – L4.)distance from skin-Adult male – 4.7 cm( at L3 – L4.)

Width Epidural space (mm) Thickness of duraWidth Epidural space (mm) Thickness of dura

Cx 1.0 – 1.5 2.0 – 1.5Cx 1.0 – 1.5 2.0 – 1.5 Upper thoraxicUpper thoraxic 2.5 – 3.0 1 2.5 – 3.0 1 Lower thoraxic 4 – 5 1 Lower thoraxic 4 – 5 1 Lumbar 5 – 6 0.66 – 0.33Lumbar 5 – 6 0.66 – 0.33

Factors affecting Epidural depthFactors affecting Epidural depth : : Maximum depth at L3 – L4. Maximum depth at L3 – L4.

1) Weight1) Weight2) Technique 2) Technique 3) Angle of needle. 3) Angle of needle. 4) Position of patient.4) Position of patient.5) Ethnic origin.5) Ethnic origin.6) Edema.6) Edema.

Contents: Contents:

1) 1) Connective tissue:Connective tissue: Strong bands & connection between dura & ant. Long. Ligament – Strong bands & connection between dura & ant. Long. Ligament –

So space is practically non-existent. Space is more extensive So space is practically non-existent. Space is more extensive & distensible posteriorly. & distensible posteriorly.

2) 2) Epidural veins:Epidural veins: Valveless veins from int. vertebral venous plexus.Valveless veins from int. vertebral venous plexus. Venacaval compression distends epidural vein so decreased dose Venacaval compression distends epidural vein so decreased dose

is required in pregnancy. is required in pregnancy.

3) 3) Spinal arteriesSpinal arteries. . 4) 4) Epidural lymphaticsEpidural lymphatics: :

5) 5) Epidural fatEpidural fat: In children less than 6: In children less than 6 years has spongy, gelateneous lobules &years has spongy, gelateneous lobules & distinct space so more rapid spread of drug.distinct space so more rapid spread of drug.

Plica mediana dorsalis:Plica mediana dorsalis:

Dorsomedian connective tissue between Dorsomedian connective tissue between dura & ligamentum flavum .Seen more dura & ligamentum flavum .Seen more extensively in area of spinal curves .extensively in area of spinal curves . Located in midline which may divide Located in midline which may divide epidural space into right & left halvesepidural space into right & left halves & narrow space in midline. In some& narrow space in midline. In some persons a complete membrane in persons a complete membrane in dorsomedian plane seen between dura dorsomedian plane seen between dura and ligamentum flavum and ligamentum flavum k /a plica mediana dorsalis . k /a plica mediana dorsalis .

IMP:IMP:

Difficulty in insertion of needle or catheter in midline – can results intoDifficulty in insertion of needle or catheter in midline – can results into

deposition of drug slightly on one or other side.deposition of drug slightly on one or other side.

Can lead to spotty / unilateral anaesthesia.Can lead to spotty / unilateral anaesthesia.

Difficulty in advancing catheter freely.Difficulty in advancing catheter freely.

Can cause coiling of epidural catheter inside.Can cause coiling of epidural catheter inside.

Pressure in Epidural space:Pressure in Epidural space:

- - Negative pressure Negative pressure - More at sites of firm attachment thoraxic (up to -15)>lumbar- More at sites of firm attachment thoraxic (up to -15)>lumbar

>sacral >sacral - Non-existence in Cx & sacral area.- Non-existence in Cx & sacral area. - 12% have no negative pressure so techniques using negative- 12% have no negative pressure so techniques using negative pressure for detection of space is not useful in such pts.pressure for detection of space is not useful in such pts.

Factors affecting negative pressure:Factors affecting negative pressure:

1) Marked flexion 1) Marked flexion 2) Young person 2) Young person 3) Old people with ligament changes 3) Old people with ligament changes 4) pt. straining & tense 4) pt. straining & tense

Thoracic Epidural AnatomyThoracic Epidural Anatomy

- Spinous pr. in upper thoraxic T1 - T4- Spinous pr. in upper thoraxic T1 - T4 & T10 – T12 are more horizontal.& T10 – T12 are more horizontal.

- In midthoracic region – pr. are - In midthoracic region – pr. are angulated in such a way that the tipangulated in such a way that the tip of spinous process of upperof spinous process of upper vertebrae rest on origin of lower vertebrae rest on origin of lower spinous pr.spinous pr.

- Because of this anatomical difficulty- Because of this anatomical difficulty it is difficult to attempt a midline it is difficult to attempt a midline entry into epidural space. entry into epidural space.

-So midline approach can be used So midline approach can be used for upper or lower thoracic region.for upper or lower thoracic region.

- In midthoracic region paramedian - In midthoracic region paramedian approach is preferred whichapproach is preferred which

however can perform at any level. however can perform at any level.

- Only marginal increase in space - Only marginal increase in space achieved by flexion of spineachieved by flexion of spine

- however this small increase can - however this small increase can facilitate entry of thick epidural facilitate entry of thick epidural

needle. needle.

- While using hanging drop technique for identification of space pt. should- While using hanging drop technique for identification of space pt. should

assume sitting position because of increase in negative pressure in assume sitting position because of increase in negative pressure in

sitting position. sitting position.

- with loss of resistance technique lateral & sitting decubitus can be used.- with loss of resistance technique lateral & sitting decubitus can be used.

- Thoracic epidural –carries more risk & complication.- Thoracic epidural –carries more risk & complication.

CERVICAL EPIDURAL SPACECERVICAL EPIDURAL SPACE

Cx spinal pr. are not angulated & horizontal Cx spinal pr. are not angulated & horizontal

approach is indicated as in lumbar region. approach is indicated as in lumbar region.

C7 – T1 is widest, easiest space to use.C7C7 – T1 is widest, easiest space to use.C7

is prominent landmark.is prominent landmark.

Sitting position is used because of betterSitting position is used because of better

palpation of C7 process.palpation of C7 process.

Lig. Flavum is quite thin & can be reached quite Lig. Flavum is quite thin & can be reached quite

superficially.superficially.

A gentle click may be appreciated while piercing A gentle click may be appreciated while piercing

Lig. Flavum.Lig. Flavum.

At C6 – C7 or C7 – T1 epidural space width—3 – 4 mm which At C6 – C7 or C7 – T1 epidural space width—3 – 4 mm which

becomes narrower in higher segments where meningeal dura & becomes narrower in higher segments where meningeal dura &

endosteal dura fuses at foramen magnum. endosteal dura fuses at foramen magnum.

Anatomy of sacrumAnatomy of sacrum::

Triangular shaped bone.Triangular shaped bone.

Fusion of lamina of five vertebralFusion of lamina of five vertebral

segments by 20 th year of life.segments by 20 th year of life.

A part of pelvis.A part of pelvis.

Anterior surface – smooth supporting Anterior surface – smooth supporting vessels, rectum, fetal head.vessels, rectum, fetal head.

Posterior surface – rough forms sacral Posterior surface – rough forms sacral crest (fusion of spinous processes)crest (fusion of spinous processes)

Fifth spinous process is unfused.Fifth spinous process is unfused.

Failure of this fusion results in Failure of this fusion results in HIATUS.HIATUS.

V or U shaped notch.V or U shaped notch.

Unfused lamina on each side Unfused lamina on each side forms cornua.forms cornua.

Communicates with sacral portion Communicates with sacral portion of vertebral column.of vertebral column.

Covered by sacrococcaygel Covered by sacrococcaygel ligament.ligament.

On each side of midline 4 pairs of foramina transmitting anterior divisionOn each side of midline 4 pairs of foramina transmitting anterior division

of spinal nerves are formed. Fifth is absent.of spinal nerves are formed. Fifth is absent.

Sacral canal:Sacral canal:

- Continuation of vertebral canal.- Continuation of vertebral canal.

- Curved – 3-4 inch longitudinal triangular space.- Curved – 3-4 inch longitudinal triangular space.

- Dural sac fills completely the vertebral canal except potential epidural- Dural sac fills completely the vertebral canal except potential epidural

space.space.

- Sac ends between S1 – S2 vertebrae.- Sac ends between S1 – S2 vertebrae.

- Mean distance between apex of hiatus and dural sac is 47 mm.- Mean distance between apex of hiatus and dural sac is 47 mm.

- As child grows up – axis of sacrum compared to lumber spine- As child grows up – axis of sacrum compared to lumber spine

changes so sacral hiatus becomes difficult to locate & may evenchanges so sacral hiatus becomes difficult to locate & may even

close.close.

Contents:Contents:

- Fluidy fat & loose areolar tissue - Fluidy fat & loose areolar tissue

- Epidural veins- Epidural veins

ANATOMIC CONSIDERATION Of NEUROAXIAL BLOCKADEANATOMIC CONSIDERATION Of NEUROAXIAL BLOCKADE (in pediatrics patients.)(in pediatrics patients.)

Procedures: Procedures:

1) Caudal A1) Caudal A

2) Epidural A:2) Epidural A:a) Intervertebral route a) Intervertebral route

ThoracicThoracicLumbarLumbar

b) Sacral epidural b) Sacral epidural

3) Spinal A 3) Spinal A

Caudal A:Caudal A:

- Mainly performed in infants & young children, - Mainly performed in infants & young children, usually combined with light GA.usually combined with light GA.

- Fluidity of epidural fat – easy to introduce a catheter in epidural- Fluidity of epidural fat – easy to introduce a catheter in epidural

space for long lasting analgesia.space for long lasting analgesia.

- This approach can be used to introduce catheter which can be- This approach can be used to introduce catheter which can be threaded cranially to perform lumber / thoracic A with out threaded cranially to perform lumber / thoracic A with out approaching the epidural space through lumber / thoracicapproaching the epidural space through lumber / thoracic intervertebral space.intervertebral space.

- Distance from skin to sacral epidural space < 20 mm from skin- Distance from skin to sacral epidural space < 20 mm from skin & not influenced by age / weight.& not influenced by age / weight.

Intervertebral epidural A:Intervertebral epidural A:

- Because subcutaneous tissue & vertebral ligaments are less - Because subcutaneous tissue & vertebral ligaments are less densely packed in infants & young children LOR felt as densely packed in infants & young children LOR felt as needle advances Lig. Flavum is LESS SIGNIFICANT than in adults.needle advances Lig. Flavum is LESS SIGNIFICANT than in adults.

- Midline approach is safer than paramedian approach. - Midline approach is safer than paramedian approach.

- Previous epidural A – may result in proliferation of connective tissue, - Previous epidural A – may result in proliferation of connective tissue, Adhesion forms between dura matter & Lig. Flavum due to Adhesion forms between dura matter & Lig. Flavum due to inflammation which reduces spread of LA during next epidural A.inflammation which reduces spread of LA during next epidural A.

- In pts. > 6 years, for continuous analgesia technique intervertebral epidural - In pts. > 6 years, for continuous analgesia technique intervertebral epidural approach is preferred over caudal approach.approach is preferred over caudal approach.

1) 1) Lumbar Epidural ALumbar Epidural A

- Spinal cord ends at lower level in children. Safer to select- Spinal cord ends at lower level in children. Safer to select

L4 – L5 vertebrae or L5 – S1 space for epidural.L4 – L5 vertebrae or L5 – S1 space for epidural.

- Line joining to illiac creast – L5 vertebrae – anatomic landmark. - Line joining to illiac creast – L5 vertebrae – anatomic landmark.

- Distance from skin – epidural space varies with pts. age & size - Distance from skin – epidural space varies with pts. age & size

1 mm / kg – (6 mth – 10 years).1 mm / kg – (6 mth – 10 years).

2) 2) Sacral Epidural A:Sacral Epidural A:

- In children because of incomplete ossification of sacrum there are true - In children because of incomplete ossification of sacrum there are true posterior sacral interspace suitable for epidural approach at anyposterior sacral interspace suitable for epidural approach at any sacral level.sacral level.

- Easiest through S2 – S3 in lateral position.- Easiest through S2 – S3 in lateral position.

- Interspace located by line joining 0.5 – 1 cm below two PSIS.- Interspace located by line joining 0.5 – 1 cm below two PSIS.

- Distance from skin – epidural space is less than at lumber level - Distance from skin – epidural space is less than at lumber level because of lack of lumber lordosis.because of lack of lumber lordosis.

- Can be used as alternative procedure to caudal A & lumbar A. when- Can be used as alternative procedure to caudal A & lumbar A. when inapplicable / failure. inapplicable / failure.

- Since sacral vertebrae not fused possible damage to ossification- Since sacral vertebrae not fused possible damage to ossification nuclei & danger of crossing cartilaginous structure – use short,nuclei & danger of crossing cartilaginous structure – use short, short bevel & not too thin caudal, epidural or spinal needle.short bevel & not too thin caudal, epidural or spinal needle.

3) 3) Thoracic epidural A:Thoracic epidural A:

- - Rarely performed in pead pts.Rarely performed in pead pts.

- Midline or paramedian approach can be used.- Midline or paramedian approach can be used.

- Whatever route used this approach is hazardous because of - Whatever route used this approach is hazardous because of

danger of direct trauma to spinal cord.danger of direct trauma to spinal cord.

- Must be performed by expert anesthetists on anaesthetized children.- Must be performed by expert anesthetists on anaesthetized children.

Spinal A:Spinal A:

- Subarachanoid space is incompletely divided by denticulate Lig. laterally & - Subarachanoid space is incompletely divided by denticulate Lig. laterally & SA septum anteriorly.SA septum anteriorly.

Volume of CSF (4 ml / kg) is double than adults (2 ml / kg). Volume of CSF (4 ml / kg) is double than adults (2 ml / kg).

50% of CSF volume in spinal SA space. 50% of CSF volume in spinal SA space.

influencesinfluences pharmacokinetics pharmacokinetics

CSF pressure 30 – 40 cm of H2O in recumbent pts. again of drug.CSF pressure 30 – 40 cm of H2O in recumbent pts. again of drug. decrease in anaesthetized childrendecrease in anaesthetized children

- As in adults, Artery of admkiwiz entering spinal cord at T8 – L3 - As in adults, Artery of admkiwiz entering spinal cord at T8 – L3 responsible for major blood supply of spinal cord.responsible for major blood supply of spinal cord.

- Any lesion of this Artery can lead to spinal ischemia & subsequent - Any lesion of this Artery can lead to spinal ischemia & subsequent permanent paraplegia.permanent paraplegia.

- Younger is pt. – shorter is duration of block.- Younger is pt. – shorter is duration of block.

- Especially useful in pts. – Premature babies age < 4 mth of age who born - Especially useful in pts. – Premature babies age < 4 mth of age who born premature & suffered from neonatal respiratory distress or who are at premature & suffered from neonatal respiratory distress or who are at

risk of developing apnea following GA.risk of developing apnea following GA.