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Chapter 3

The typical epidurogram (Fig 3.1b)

Epidural Model showing fairly typical spread of epidural contrast, with prominent contrast flow at the level of the left T12/L1 nerve-root.

Chapter 3

The typical epidurogram (Fig 3.8a-d)

Epidural AP view 00.00-00.38

There is early filling (within 15s) of the lateral bands or channels of contrast up to T8 on the left, and T12 on the right (Fig 3.8a). Only after 40s does the central body of contrast start to appear (Fig 3.8b), accompanied by transforaminal spill. After 60s the mass of contrast shows thickening and consolidation (Fig 3.8c), with increased spill, which is more clearly seen in the corresponding radiograph (Fig 3.8d), with contrast extending from T7-L5.

Lateral view 00.39-00.51

There is a slight kyphosis in this 33 year-old. The spread of epidural contrast is fairly typical, although the posterior column is extended, as is frequently seen in the presence of a kyphotic curve.

Chapter 3

The typical epidurogram (Fig 3.9a-f)

Epidural AP view 00.00-00.59

The initial contrast flow appears, after 20s, as a narrow dense central aggregation which flows fairly rapidly, in a cephalad direction, with only a slow and small caudal extension (3.9a). The left L4-5 nerve spill is evident. With continuing injection, the central mass of contrast thickens and ascends to L3 by 30s, and lateral channelling commences (3.9b). After 50s, bilateral lateral columns are evident, with thickening of the mass of central contrast and further transforaminal spill (3.9c). Further consolidation of the entire mass of contrast occurs up until 70s (3.9d)

Lateral view 01.03-01.32 (3.9f)

The lumbar spine shows a loss of the typical lordosis, and a fairly characteristic spread of contrast in anterior and posterior columns, although the posterior column is attenuated in places.

Chapter 4

Complicated epidural blocks (Fig 4.6a&b)

Subarachnoid AP view 00-00-00.24

Contrast initially appears as a faint central column, from L1 to S2, with linear streaking, and a small dense collection at S2. The upper level of contrast extends rapidly upwards, before disappearing out of view above T10

Lateral view 00.25-00.41

Apart from brief glimpses of the contrast collection at S2, it is impossible to visualise any other contrast in this film.

Chapter 4

Complicated epidural blocks (Fig 4.8a&b)

Epidural following two dural punctures AP view 00.00-01.33

Contrast initially appears as a central linear band extending upwards from the catheter tip at L4, to L2. As the body of contrast thickens there is mostly cephalad extension, eventually tapering off in the thoracic spine at T5. The body of contrast is highly fragmented, with numerous filling defects, probably representing CSF.

Lateral view 01.34-01.51

The majority of the contrast is confined to the posterior epidural column, presumably by a large escaped volume of CSF, with only a small volume anteriorly at L4-5.

Chapter 5

The subdural and intradural spaces (Fig 5.2c)

Subdural Model illustrating contrast in the subdural space.

Chapter 5

The subdural and intradural spaces

Subdural Cartoon illustrating contrast flowing into the subdural space, through a subdural catheter.

Chapter 5

The subdural and intradural spaces (Fig 5.4a&b)

Intradural Lateral view 00.00-00.47

The initial appearance of intradural contrast is that of two faint masses at L2-3, which rapidly coalesce to form a single dense mass which swells anteriorly into the vertebral canal and also extends vertically, from L2-L4

AP view 00.47-01.02

The fully-formed central mass of intradural contrast, with an irregular outline is seen to extend from L2 to L4.

Chapter 5

The subdural and intradural spaces (Fig 5.4c)

Intradural The cartoon illustrates the dense, sharply demarcated, mass of intradural contrast, with a fairly smooth outline.

Chapter 5

The subdural and intradural spaces (Fig 5.5b)

Intradural AP view 00.00-00.16

Injection of contrast produced increasing back pain and was ceased after 4mL. A small dense mass of contrast is seen in the midline at L3-4.

Lateral view 00.16-00.24

The characteristic dense appearance of intradural contrast is evident at L3-4, with a typical anterior bulge. Even though only 4mL of contrast has been injected there is retrograde flow around the catheter to the skin.

Chapter 5

The subdural and intradural spaces (Fig 5.7a&b)

Intradural AP view 00.00-00.17

The central body of intradural contrast is fully formed from L3-L5, while the left-sided mass of epidural contrast is seen to spread from L4-5, down to the S1 and S2 nerve-roots.

Lateral view 00.17-00.30

There is considerable overlap between the upper mass of intradural contrast, which extends from L3-L4, and the lower mass of epidural contrast from L4-S2, which shows nerve root spill from L4 downwards.

Chapter 5

The subdural and intradural spaces (Fig 5.7c)

Intradural/epidural Model illustrating the combined appearance of overlapping intradural and epidural contrast.

Chapter 5

The subdural and intradural spaces (Fig 5.8a&b)

Intradural/epidural AP view 00.00-01.10

Intradural contrast appears as a dense compact band to the left of the midline at L3-4, and slowly thickens and spreads to the epidural space, at around 00.22s, when it flows profusely and for some distance around the left L4 nerve root.

Lateral view 01.12-01.17

The two separate masses of contrast are clearly delineated, with the larger intradural mass behind the smaller anterior epidural collection, between L2-L4.

Chapter 5

The subdural and intradural spaces (Fig 5.9a&b)

Intradural AP view 00.00-00.03

The central mass of intradural contrast, containing two large air-bubbles, appears from L2-L3.

Lateral view 00.03-00.11

The mass of intradural contrast now extends from L2-L4, with retrograde leakage of contrast around the catheter to the subcutaneous tissues.

Chapter 5

The subdural and intradural spaces (Fig 5.14d)

Intradural/subdural Model showing the low dense mass of intradural contrast at the lumbosacral level, and the upper more fragmented body of subdural contrast.

Chapter 5

The subdural and intradural spaces (Figs 5.18a-d)

Intradural injection A series of cartoons depicting the possible consequences of injecting fluid into the intradural space: The intradural space is created and develops as a swelling mass which spreads anteriorly.

Chapter 5

The subdural and intradural spaces (Figs 5.18a-d)

Intradural injection A series of cartoons depicting the possible consequences of injecting fluid into the intradural space: With increasing volume and pressure accumulating within the intradural space, there is retrograde flow around the catheter to the epidural space.

Chapter 5

The subdural and intradural spaces (Figs 5.18a-d)

Intradural injection A series of cartoons depicting the possible consequences of injecting fluid into the intradural space: The swelling intradural mass ruptures through the remaining few layers of the dura allowing fluid to flow into the subdural space.

Chapter 6

Failed epidural blocks and misplaced catheters (Fig 6.4)

Epidural and catheter escape AP view 00.00-00.14

Injection through the lower catheter produces only a faint diagonal band of contrast, outlining the lateral border of the left psoas muscle. At 00.17-00.24, injection through the lower catheter produces a typical bilateral epidural spread of contrast from T10 to L4.

Lateral view 00.24-00.35

The characteristic appearance of epidural contrast is seen, together with the escaped contrast from the lower catheter which has collected anteriorly, around the psoas muscle.

Chapter 6

Failed epidural blocks and misplaced catheters (Fig 6.6)

Catheter escape AP view 00.00-0013

Contrast is initially seen to escape through the right L2-3 intervertebral foramen, to outline the psoas muscle. About 4s later, a narrow lateral column of epidural contrast begins to appear at L2-3, before extending up to L1.

Chapter 6

Failed epidural blocks and misplaced catheters (Fig 6.7a&b)

Paravertebral injection AP view 00.00-01.00

Contrast flows initially into the left paravertebral space at L1-2, and spreads up to T10, then across towards the midline, as the body of contrast thickens.

Lateral view 01.00-01.11

The paravertebral contrast accumulates posterolateral to the T10-L2 vertebral bodies initially, and then spreads anteriorly.

Chapter 6

Failed epidural blocks and misplaced catheters (Fig 6.8a&b)

Epidural AP view, lower catheter, 00.00-00.13

There is a mild thoracolumbar scoliosis (primary curve convex to the right). Contrast injected into the lower epidural catheter at L3 produced only a small very and faint localised collection in the epidural space, before it leaked retrogradely around the catheter producing two distinct dense irregular masses of contrast external to the vertebral column, outlining two groups of erector spinae muscles.

AP view, upper catheter, 00.13-00.47

Injection through the upper catheter at L2 now resulted in a fairly normal but restricted spread of contrast, starting at L3 on the right, and only ascending to T12. Some of the contrast also leaked retrogradely, thickening the mass of extravasated contrast.

Lateral view; 00.48-01.05 (Fig 6.8c)

The extravasated contrast appears in two distinct areas of the erector spinae muscles with the epidural contrast exiting the upper catheter being fairly uniformly spread across the epidural space.

Chapter 7

Failed epidural blocks caused by an obstructive septum (Fig 7.5d)

Epidural A model showing the left-sided unilateral spread of contrast, almost certainly caused by a midline septum, with profuse transforaminal contrast escape.

Chapter 7

Failed epidural blocks caused by an obstructive septum (Fig 7-9a-c)

Transverse septum Lumbar AP view 00.00-01.04

A central aggregation of epidural contrast appears at L3 around the catheter tip and gradually spreads vertically in a predominantly cephalad direction. Above L3 the mass of contrast is very patchy with numerous filling defects and air bubbles, and at T11 gradually tapers off. The appearance is characteristic of a posterior distribution of contrast.

Thoracic AP view 01.06-01.49

The mass of contrast continues to ascend, while tapering off to a fine point at T5.

Upper lateral view 01.56-02.08

This rather poor quality film shows a moderate degree of kyphosis (for a 47 year-old) and a high posterior column of epidural contrast.

Chapter 8

Spinal deformity and epidural block (Fig 8.4a&b)

Epidural AP view 00.00-00.33

There is a mild degree of scoliosis, convex to the left, and the contrast is almost exclusively right-sided, with prominent foraminal spill of contrast.

Chapter 8

Spinal deformity and epidural block (Fig 8.9a-c)

Epidural AP view 00.00-00.05

Around the base of the Harrington rod, there is a low predominantly right-sided distribution of contrast, from L1-5, with marked right foraminal spill.

Lateral view 00.07-00.11

There is a restricted, low spread of epidural contrast, below the rod.