Neuraxial Anesthesia Practice Flashcards

Comprehensive vocabulary flashcards covering the anatomy, physiology, mechanisms, and complications of neuraxial anesthesia (spinal, epidural, and caudal) based on the lecture transcript.

Lordosis

The concave curvature characteristic of the Cervical ($7$ vertebrae) and Lumbar ($5$ vertebrae) regions of the spine.

Kyphosis

The convex curvature characteristic of the Thoracic ($12$ vertebrae) region of the spine.

Tuffier’s line

An anatomic landmark used for location, defined as a line drawn across the top of the iliac crest.

Ligamentum flavum

Also known as the yellow ligament, it is the strongest and thickest ligament in the lumbar area, composed of elastic fibers and connecting the laminae of the vertebrae.

Dura mater

Known as the 'tough mother,' it is the outermost protective meningeal layer of the spinal cord.

Arachnoid mater

The second meningeal layer, described as the 'cobweb mother,' which continues until approximately $S_2$.

Pia mater

The 'soft mother' layer in direct contact with the outer surface of the spinal cord; it is a very vascular area that ends at $L_1$ with the spinal cord.

Epidural space

The potential space located between the dura mater and the ligamentum flavum.

Subarachnoid space

The space below the arachnoid mater that contains Cerebrospinal Fluid (CSF); also known as the intradural or intrathecal space.

Conus medullaris

The anatomical term for where the spinal cord ends, typically at $L_1$ in adults.

Cauda equina

The collection of nerve roots below $L_1$ that travel caudad before exiting, resembling a 'horse's tail.'

Filum terminale

A coccygeal ligament of fibrous tissue that secures the lower end of the spinal cord.

Anterior spinal artery

A single artery arising from the vertebral arteries providing $75\%$ of the blood supply to the spinal cord, specifically the ventral horn; it carries high risk for ischemia due to limited collaterals.

Artery of Adamkiewicz

A critical blood supply arising from the aorta at $T_9-T_{12}$ on the left side only, supplying the anterior lower $2/3$rds of the spinal cord.

Cerebrospinal Fluid (CSF) Pressure

The normal fluid pressure of CSF, measuring between $10-20\,cmH_2O$.

CSF Specific Gravity

The specific gravity of CSF at $37^{\circ}C$ is $1.005$ (range $1.003 - 1.009$).

B fibers

Preganglionic autonomic nerve fibers that are the first modality lost during neuraxial blockade; these are blocked $2$ to $6$ segments higher than sensory fibers.

A alpha fibers

The thickest nerve fibers responsible for motor function; they are the last modality lost and the first to return after a block.

T4 dermatome

The sensory level corresponding approximately with the nipple line.

T10 dermatome

The sensory level corresponding approximately with the umbilicus.

Hyperbaric solution

A local anesthetic solution that is more dense (heavier) than CSF (Local + glucose), causing it to 'sink' to dependent areas.

Hypobaric solution

A local anesthetic solution that is less dense (lighter) than CSF (Local + sterile $H_2O$), causing it to 'rise' or 'float.'

Cardiac accelerators

Sympathetic fibers arising from $T_1-T_4$; blockade of these can lead to profound hypotension, bradycardia, and decreased contractility.

Total spinal

A complication involving apnea due to medullary hypoperfusion and direct phrenic nerve blockade ($C_3-C_5$), resulting in loss of consciousness and cardiovascular collapse.

Tuohy needle

An $17-18\,g$ needle, $3-3.5\,\text{inches}$ long with a blunted bevel and a $15-30$ degree curve at the tip, commonly used for epidural placement.

Test Dose

A safeguard for epidurals consisting of $3\,ml$ of Lidocaine $1.5\%$ with epinephrine $1:200,000$ used to identify intravascular or subarachnoid injection.

Postdural puncture headache (PDPH)

A headache caused by CSF leakage from a dural defect, typically frontal or occipital, which is aggravated by sitting or standing and relieved by lying flat.

Epidural blood patch

The treatment for PDPH involving the injection of $15-20\,ml$ of the patient's own blood at or one space below the dural puncture site.

Transient Neurological Symptoms (TNS)

Pain after block resolution lasting $2-7$ days, specifically associated with the use of $5\%$ lidocaine.

Baricity

The resting position of two fluids with different specific gravities, such as local anesthetic compared to CSF.