Epidural Anaesthesia: Images, problems and solutions

One of the first epidurograms ever performed (1926), using oily contrast. The film was taken 1 h post-injection.

Classification of the patients being investigated.

(a) Typical AP (anteroposterior) epidurogram with 'Christmas tree' appearance from T11 to L5. The transforaminal escape of contrast at several vertebral levels is indicated by the red arrows, with only a single outline appearing at some, and a double outline at others. In this case, there is a large volume of contrast spill through the left T12–L1 intervertebral foramen. (b) Three-dimensional model of the epidural space, in the same patient. AP view. 'Contrast' escaping from the left T12–L1 intervertebral foramen is prominent.

Figure 3.2

(a) Typical AP (anteroposterior) epidurogram with 'Christmas tree' appearance from T5 to L4, and transforaminal contrast spill at most levels. The left-sided escape of thoracic contrast from T6 to T9 is arrowed. (b) A more detailed AP epidurogram in the same patient, highlighting the thoracic spread of contrast. The left T6–T9 spinal nerves are arrowed.

Figure 3.3

Fairly typical anteroposterior (AP) epidurogram showing marked contrast escape from the right L3–4 intervertebral foramen (lower arrow). Multiple small air bubbles are present within the body of epidural contrast (upper arrows).

Figure 3.4

Anteroposterior (AP) epidurogram following L4–5 epidural insertion, showing a low body of contrast from L3 downwards, with marked contrast escape from the left S2 and right S1 foramina (arrowed).

Figure 3.5

Lateral epidurogram showing typical contrast distribution from T8 to L5. The anterior and posterior columns are arrowed in red, and the L1–2, L2–3 intervertebral foramina in blue. (Same patient as Fig. 3.1, p.11.)

Figure 3.6

Lateral epidurogram showing low lumbosacral contrast distribution, below L3. Contrast escaping from the S1 and S2 sacral foramina is arrowed. (Same patient as Fig. 3.4, p.13.)

Figure 3.7

Anteroposterior (AP) epidurogram after patient-controlled epidural analgesia (PCEA) infusion for several hours. The right border of the contrast is blurred (arrows) by the presence of fluid. The contrast is almost entirely right-sided because of a midline septum.

Figure 3.8

(a–c) Sequence of anteroposterior (AP) fluoroscopic images during contrast injection. (a) At 15s post-injection, there is bilateral channelling of contrast from T8 to L4 on the left and from T12 to L2 on the right (red arrows). (b) By 40s, contrast has spread to T8 bilaterally (red arrows), with early central filling. Left L1–2 and L3–4 transforaminal spill is appearing (blue arrows). (c) Around 60s, the central body of contrast has become more dense. The left L1–2 and L3–4 transforaminal spill is more pronounced. (d) An AP radiograph, in the same patient, at 70s, showing extensive bilateral contrast spread from T7 to L5 (red arrows) and prominent spill at left L1–2 and L3–4 (blue arrows).

Figure 3.9

(a–d) Sequence of anteroposterior (AP) fluoroscopic images during contrast injection. (a) At 20s, a small central body of contrast appears (red arrows), with spill through the left L4–5 intervertebral foramen (blue arrow). (b) By 30s, the central body of contrast has widened and spread to L3 (lower red arrow), and lateral spread of contrast has appeared up to L2 on the right (upper red arrow). There is increased left L4–5 transforaminal nerve spill (blue arrow). (c) After 50s, the central body of contrast has again extended, while lateral spread has reached L1 on the left and T10 on the right (red arrows). The left L3–4 transforaminal spill has become more prominent and right L4–5 spill has appeared (blue arrows). (d) At 70s, the contrast has extended to left T12 and generally thickened in appearance. (e) The AP radiograph, in the same patient at 80s, shows the asymmetrical central body of contrast and the lateral channelling, which is a little patchy. The L3–4 and L4–5 transforaminal spill is arrowed in blue. (f) The lateral radiograph at 110s, showing a fairly typical spread of contrast, although it is patchy and attenuated in places. The L3–4 and 4–5 transforaminal nerve spill is arrowed in blue.

Figure 3.10

(a) Anteroposterior (AP) epidurogram in an elderly patient with kyphoscoliosis. There are widespread bony degenerative changes, and extensive transforaminal spill of contrast (arrowed on left), the left L1 spill being mostly cephalad (upper arrow). (b) Lateral epidurogram showing a marked kyphosis. There is a high posterior column of contrast and pooling of contrast in some areas (arrowed).

Figure 3.11

(a) Anteroposterior (AP) epidurogram in an elderly patient with kyphoscoliosis. There are widespread bony degenerative changes. The central aggregation of contrast is narrow and there is little transforaminal spill, suggesting a predominantly posterior distribution of contrast. (b) Lateral epidurogram showing a marked kyphosis, and confirming the extensive and mostly posterior distribution of contrast, with an acute mid-thoracic angulation (arrowed).

Figure 3.12

Axial computed tomography (CT) scan at L3 showing epidural contrast escaping from the posterior epidural space (X) through both intervertebral foramina (red arrows). Subdural contrast (blue arrows) encloses the nerve roots of the cauda equina.

Figure 3.13

(a) A typical axial magnetic resonance imaging (MRI) scan at the level of the L3 lamina, without contrast. The posterior epidural space (red arrows) is medial to the ligamentum flavum and vertebral lamina. The L3 nerve roots are indicated. (b) A typical sagittal lumbosacral MRI scan, with the posterior epidural space arrowed in red. The much smaller anterior epidural space is arrowed in blue.

Figure 4.1

(a) Dermatomal spread of analgesia to pinprick (lighter-coloured areas) following high epidural block (Case History 4.1), with numb cheeks and loss of corneal reflex from associated bilateral trigeminal nerve block. (b) Anteroposterior (AP) epidurogram in the same patient. Extensive thoracic contrast spread is evident (red arrows), up to T5, with marked transforaminal spill on the left. (c) Lateral epidurogram in the same patient following high epidural block, showing extensive spread of contrast, particularly in the posterior epidural column (red arrow). (d) An AP epidurogram in the same patient 4years later, showing prominent lateral channels of contrast (arrowed), but not such extensive spread as previously.

Figure 4.2

(a) Anteroposterior (AP) radiograph following 2mL of subarachnoid contrast, with a faint appearance of linear streaking from T8 to L1 (arrowed). Note the caudally pointing catheter tip. (b) Lateral radiograph after 2mL of subarachnoid contrast, with characteristic linear streaking between T8 and L4 (arrowed). (c) An AP radiograph following 6mL of contrast, (same patient) with a mass of subarachnoid contrast now extending from T7 to L2 (arrowed). The faint appearance of linear streaking at L2 gradually thickens to a dense mass in the lower thoracic spine. (d) Lateral radiograph following 6mL of contrast, (same patient) with a mass of subarachnoid contrast extending from T6 to L4 (arrowed). The linear streaking at L4 gradually thickens above, to a denser mass in the lower thoracic spine.

Figure 4.3

(a) Anteroposterior (AP) radiograph (negative image) showing the lower end of an extensive column of subarachnoid contrast, at the level of the conus medullaris, L2, extending up to T12 (arrowed). (b) Lateral radiograph (negative image) showing an extensive column of subarachnoid contrast with faint linear streaking from T12 to L5 (arrowed), following turning of the patient.

Figure 4.4

Diagram illustrating the possible positioning of the openings of a typical lateral eye catheter.

Figure 4.5

Diagram illustrating the possible multicompartment positioning of the opening of a terminal eye catheter.

Figure 4.6

(a) Anteroposterior (AP) radiograph showing subarachnoid contrast from T10 to S2 (arrowed). The contrast below L1 is streaky and barely visible, apart from the dense collection at the base of the dural sac at S2 (lower arrow). (b) Lateral radiograph demonstrating dense subarachnoid contrast at the base of the dural sac at S2 (lower arrow). Above this, there is only the faint linear streaking of contrast (upper arrows).

Figure 4.7

Anteroposterior (AP) view of a degenerative lower thoracolumbar spine, with epidural contrast from T12 to L4 (lower red arrow) and foraminal spill (upper red arrows). The central subarachnoid mass of contrast (blue arrows) is obscured by epidural contrast at higher vertebral levels.

Figure 4.8

(a) Anteroposterior (AP) epidurogram following two dural punctures. The extensive body of epidural contrast is narrowed and contains multiple filling defects (arrowed), almost certainly caused by the accumulation of cerebrospinal fluid (CSF). (b) Lateral epidurogram showing mostly posterior epidural contrast, with a large filling defect anteriorly (upper arrows), presumably due to accumulation of CSF, with an abrupt anterior column cut-off at the top of L4 (lower arrow).

Figure 4.9

Axial computed tomography (CT) scan at L3 with two areas of fluid collection (presumably cerebrospinal fluid) in the epidural space (arrowed) following two dural punctures.

Figure 4.10

Photograph of right Horner's syndrome in a labouring patient. Note the small pupil and slight ptosis.

Figure 4.11

Photograph of left Horner's syndrome in a labouring patient, with marked conjunctival injection, miosis and mild ptosis.

Figure 4.12

Anteroposterior (AP) epidurogram showing a 'normal' spread of contrast, which only ascended to T11/12 (arrowed), in a patient with (right) Horner's syndrome.

Figure 5.1

(a) Anteroposterior (AP) epidurogram revealing a dense mass of mostly right-sided epidural contrast (here appears black) at L1-L3, with an irregular edge and containing many air bubbles. Contrast also highlights the right L1–2 and L2–3 nerve roots (red arrows). Very faint columns of subdural contrast are visible from T6 to L1 on the left and T6 to T10 on the right (blue arrows), although the latter is partly obscured by the epidural catheter. (b) Lateral epidurogram showing the posterior epidural collection of contrast between L1 and L3 (red arrows) and a narrow anterior dense column of subdural contrast from T6 to L3.

Figure 5.2

(a) Anteroposterior (AP) epidurogram, following a high block, revealing bilateral subdural columns of contrast from T4 to L4 (arrowed), with a 'rail-road track' appearance. (b) Lateral epidurogram showing anterior and posterior columns of subdural contrast (red arrows) with a small volume of contrast in between. The intervertebral foramina (blue arrows) are characteristically empty. (c) Three-dimensional modelling of the radiographs from the same patient (3D Studio Max).

Epidural Anaesthesia / Hodder Arnold © 2012 C Collier. Part (a) reproduced from Collier CB, Gatt SP, Lockley SM. Br J Anaesth 1993; 70:462–465 with the kind permission of Oxford Journals and the authors.

Figure 5.3

(a) Anteroposterior (AP) epidurogram with predominantly right-sided column of subdural contrast from T6 to L4 (arrowed). The faint left-sided column is also indicated. (b) Detailed AP view of the same patient, to show the characteristic appearance of subdural contrast surrounding two adjacent spinal nerve roots. The outline of a posterior root ganglion is arrowed. (c) Lateral epidurogram showing faint anterior and posterior columns of subdural contrast (red arrows). There is only a small volume of midline contrast, with empty intervertebral foramina (blue arrows).

Figure 5.4

(a) Anteroposterior (AP) epidurogram of thoracolumbar spine showing dense 'sausage-shaped' mass of intradural contrast. (b) Lateral radiograph with bulging mass of intradural contrast (arrowed) in the same patient. (c) Three-dimensional modelling of the radiographs from the same patient (3D Studio Max).

Figure 5.5

(a) Anteroposterior (AP) radiograph showing small but dense mass of intradural contrast at L3–4, with no obvious epidural escape. (b) Lateral radiograph with bulging mass of intradural contrast (red arrows), between L3 and L4. Inferior to this, faint areas of contrast (blue arrow) probably indicate early epidural escape.

Figure 5.6

(a) Anteroposterior (AP) radiograph showing a fairly dense narrow midline body of intradural contrast from L1 to L4 (arrowed), with a slightly irregular outline. (b) Lateral radiograph demonstrating a posterior mass of intradural contrast (arrowed) from L1 to L4.

Figure 5.7

(a) Anteroposterior (AP) epidurogram revealing a dense central mass of intradural contrast (red arrows) from L3 to L5, with adjoining epidural contrast (blue arrows) from L4 to S1. L5 and S1 foraminal escape of contrast is seen (lower blue arrows). A minor degree of spina bifida occulta (SBO) is present at S1, but is not clearly visible in this image. (b) Lateral epidurogram showing overlapping collections of intradural (red arrows) and epidural contrast (blue arrows). (c) Three-dimensional modelling of the radiographs from the same patient (3D Studio Max; the 'epidural' catheter is depicted in blue for clarity).

Figure 5.8

(a) Anteroposterior (AP) epidurogram in the same patient as Fig. 5.7, 3years later. This time the intradural contrast (red arrows) extends from L3 to L4, with the epidural escape at the same levels, with pronounced spill at L4 on the left (lower blue arrow). Again, the spina bifida occulta (SBO) is not clearly seen. (b) Lateral radiograph with dense intradural contrast between L3 and L4 posteriorly (red arrows) with epidural contrast anteriorly (blue arrows) and L4 root spill (blue arrow).

Figure 5.9

(a) Anteroposterior (AP) epidurogram with a small but dense central mass of intradural contrast between L1 and L3 (red arrows), with a small volume of escaping epidural contrast on the right side at the same levels (blue arrows). (b) Lateral epidurogram showing two bulging masses of intradural contrast (red arrows). A small volume of epidural contrast lies anteriorly (blue arrows).

Figure 5.10

(a) Anteroposterior (AP) radiograph revealing a small dense central mass of intradural contrast at L3–4 (red arrows) with bilateral escaping epidural contrast between L2 and L5 (blue arrows). Spina bifida occulta (SBO) is evident at S1. (b) Lateral epidurogram with a dense posterior mass of intradural contrast from L2 to L5 (red arrows), with patchy escaping epidural contrast above and below (blue arrows).

Figure 5.11

(a) Anteroposterior (AP) epidurogram (lower half only). A faint collection of intradural contrast surrounds the catheter tip at L3 (red arrows), while the main body of dense intradural contrast is outlined (in green, with a blue arrow) and is seen to start at T12 and disappear off the film at T9 as it spreads to T6 (next image). (b) An AP epidurogram (upper half only) showing the upward extension of the dense column of intradural contrast to T6 (red arrows), with escaping epidural contrast appearing bilaterally at the level of the T4 foramina (blue arrows). (c) Lateral epidurogram showing the upward extension of a dense posterior column of intradural contrast from T12 to T6 (red arrows), with multiple bulges at varying positions.

Figure 5.12

(a) Anteroposterior (AP) radiograph following contrast injection in a 23-year-old parturient who suffered a dural puncture during attempted epidural block. A dense central mass of intradural contrast is seen in the mid-thoracic spine, similar to Fig. 5.10b, p.56. (b) Lateral radiograph in the same patient, showing a dense posterior column of intradural contrast, in the mid-thoracic spine (red arrows) with multiple bulges (or indentations) at varying positions, almost identical to Fig. 5.11c.

Figure 5.13

(a) Anteroposterior (AP) epidurogram showing a dense mass of intradural contrast at L2–3 (red arrows) surrounding the catheter tip, and the horizontal upper level of a column of subarachnoid contrast (blue arrow). (b) Lateral radiograph with posterior intradural contrast from L2 to L4 (red arrows) and the faint linear streaking of subarachnoid contrast anteriorly (blue arrows).

Figure 5.14

(a) Anteroposterior (AP) radiograph of thoracolumbar spine showing a mass of intradural contrast between L3 and S1 (red arrows) merging above with subdural contrast, which outlines the L2–3 and L3–4 nerve roots (blue arrows). (b) An AP close-up view of the lower lumbar and sacral area of the same patient, showing the lower end of the intradural contrast down to L5 (red arrow) and spina bifida occulta at S1 (yellow arrow). (c) Lateral view of thoracolumbar spine showing mass of intradural contrast from L3 to S1 (red arrow) and 'railroad tracks' of subdural contrast (blue arrows) above. (d) Three-dimensional modelling of the radiographs from the same patient (3D Studio Max), showing merging masses of intradural contrast below and subdural contrast above.

Epidural Anaesthesia / Hodder Arnold © 2012 C Collier. Parts a and c reproduced from Collier CB. Anaesth Intens Care 1992; 20:215–232 with the kind permission of The Australian Society of Anaesthetists Ltd.

Figure 5.15

(a) A published image labelled 'Anteroposterior (AP) radiograph of the lumbar spine with subdural contrast media' (arrowed). (b) A published image labelled 'Lateral radiograph of the lumbar spine with subdural contrast media' (arrowed).

Epidural Anaesthesia / Hodder Arnold © 2012 C Collier. Figures modified from Ajar AH, Rathmell JP, Mukherji SK. The subdural compartment. Regional Anesthesia and Pain Medicine 2002; 27:72–76, with permission.

Figure 5.16

(a) Two illustrations depicting the anatomy of the dura–arachnoid region, with an intact subdural compartment, at the dura–arachnoid interface, on the left, between the yellow arrows. On the right, the compartment has been disrupted, between the green arrows, creating a subdural space. (b) The upper illustration depicts the tearing away of the thick dura (yellow) from the filmy arachnoid, to create a subdural space, which is clearly seen in the lower electron microscope image (black arrow).

Figure 5.17

(a) Scanning electron microscopy (SEM) image showing a subdural space between the dura and arachnoid. The intradural space (I) lies parallel to the subdural space, within the innermost layers of the dura. (b) An SEM image of the meninges showing the concentric rings formed by the dural laminae. Original magnification ×300. (c) An SEM view of concentric dural laminae and an enclosed artefactual intradural space (arrowed). Original magnification ×300. (d) An SEM view of dural laminae and an enclosed artefactual intradural space (arrowed). Original magnification ×300. (e) Enhanced SEM image of individual dural laminae (black lines), surrounding an artefactual intradural space (arrowed). Original magnification ×2000. (f) An SEM image of the lumbar dural sac, with the nerve roots of the cauda equina above, enveloped in the arachnoid mater, and the presence of both intradural and subdural spaces. Original magnification ×25. (g) An SEM image of lumbar meninges showing an intradural (or fourth) space and a subdural space. Original magnification ×25. (h) An SEM image revealing the presence of an epidural catheter within a lumbar subdural space. The nerve roots of the cauda equina lie above and to the right. Original magnification ×25. (i) An SEM image of an epidural catheter within the substance of the dura, or 'intradural', showing a dural thickness of 300µm and a combined width of dura and catheter of 1360�B5;m. Original magnification ×25. (j) An SEM image (same specimen as in e) showing the cavity left behind within the dura following removal of an intradural catheter. Original magnification ×20. (k) An SEM image showing an epidural catheter migrating from an intradural space to the subarachnoid space, the arrow indicates an area of dural breakage. Original magnification ×40. (l) An SEM image (same specimen as in k) showing the cavity left behind within the dura following removal of an intradural catheter. Original magnification ×75.

Figure 5.18

A model showing a fluid mass (orange) in the intradural space, bulging anteriorly into the vertebral canal. (b) Model showing fluid escaping from the intradural space to the epidural space around the outside of an 'epidural' catheter. (c) Model showing fluid escaping from the intradural space to the subdural space, following rupture of the enclosing layers of dura. (d) Model showing fluid escaping from the intradural space to the subarachnoid space, following rupture of the surrounding dura and arachnoid. (Images supplied by Professor M. A. Reina, Madrid, Spain.)

Figure 6.1

(a) Anteroposterior (AP) epidurogram following catheter escape through the right L2–3 intervertebral foramen, with contrast outlining the right psoas muscle (arrowed). (b) Lateral epidurogram showing the escaping catheter, with contrast collecting anterior and lateral to the right psoas muscle (arrowed).

Figure 6.2

(a) Anteroposterior (AP) epidurogram following catheter escape, with contrast outlining the tendinous insertion of the left psoas muscle (arrowed). For clarity only the distal portion of the catheter is highlighted. It proceeds towards and exits through the left L4–5 intervertebral foramen. (b) Lateral epidurogram following catheter escape, with contrast collecting behind the left psoas muscle (blue arrow). Following catheter withdrawal by 2cm, further contrast injection enters the posterior epidural space (red arrow), with some extravasation to the skin (X).

Figure 6.3

Anteroposterior (AP) radiograph showing moderate scoliosis with the epidural catheter tip escaping through the right L1–2 intervertebral foramen and contrast highlighting the psoas muscle (arrowed).

Figure 6.4

Anteroposterior (AP) radiograph showing lower (red) catheter emerging through left L2–3 intervertebral foramen and contrast outlining the lateral border of the left psoas muscle (arrowed). Injection through the upper (blue) catheter results in epidural contrast spread between T10 and L4.

Figure 6.5

(a) Anteroposterior (AP) radiograph showing the epidural catheter emerging through the right L2–3 intervertebral foramen, with contrast highlighting the right psoas muscle (red arrow). Limited epidural spread is evident between L1 and L4 bilaterally (blue arrows). (b) Lateral radiograph. The epidural catheter is seen to enter the mass of psoas contrast (red arrows), which overlies the limited spread of epidural contrast (blue arrows).

Figure 6.6

Anteroposterior (AP) radiograph depicting the epidural catheter emerging through the right L2–3 intervertebral foramen with contrast highlighting the right psoas muscle. Limited epidural spread is evident between L1 and L4 (arrowed).

Figure 6.7

(a) Anteroposterior (AP) radiograph, with epidural catheter entering a left paravertebral mass of contrast, which has spread anteriorly to the midline (between the arrows) from T10 to L2. (b) Lateral radiograph showing a collection of paravertebral contrast that has spread anteriorly (between the arrows) from T10 to L2.

Figure 6.8

(a) Anteroposterior (AP) radiograph demonstrating mild thoracolumbar scoliosis. Injection of contrast through the lower L3 (red) catheter highlights two distinct left paravertebral masses (arrowed), with minimal epidural filling. (b) An AP radiograph showing the addition of the upper L2 (blue) catheter. Injection of contrast produces a slightly restricted epidural filling from T12 to L4, which is predominantly right-sided. (c) Lateral radiograph showing the apparently normal positioning of both the upper (blue) and lower (red) epidural catheters. The paravertebral collections of extravasated contrast are seen to highlight two distinct groups of the erector spinae muscles (arrowed). Minimal epidural contrast exits through the lower catheter, with reasonable spread from the upper.

Figure 7.1

Diagram of septal anatomy of the lower lumbar spine; 'a' and 'p' indicate the anterior and posterior dorsolateral space, respectively. (

Figure 7.2

(a) Anteroposterior (AP) radiograph showing a midline fissure (arrowed) within the body of contrast, indicating a dorsal midline septum. The mass of contrast is narrow and tapers off at T10 and there is little foraminal escape of contrast, both of which are features that suggest the contrast lies predominantly at the back of the epidural space. (b) Lateral radiograph confirming the predominant posterior distribution of the contrast, with a large central filling defect (arrowed), representing a probable transverse extension of a midline septum. A small volume of contrast surrounds the catheter within the erector spinae muscles.

Epidural Anaesthesia / Hodder Arnold © 2012 C Collier. Modified from Savolaine ER, Pandya JB, Greenblatt SH, Conover SR (1988) Anatomy of the lumbar epidural space: New insights using CT-epidurography. Anesthesiology 1988;68:217–220, with permission.

Figure 7.3

(a) Anteroposterior (AP) epidurogram following contrast injection through the lower (red) catheter. Contrast is totally left-sided, with profuse foraminal spill (red arrows) and retrograde flow to the erector spinae muscles and skin (blue arrow). (b) An AP epidurogram following contrast injection through the upper (blue) catheter. Initially, the contrast remains left-sided, with increasing spill and retrograde flow (blue arrow). Later, contrast appears on the right as an attenuated and fragmented lateral column from T8 to L2 (red arrows). (c) Lateral epidurogram (poor quality) following contrast injections. Between T11 and L3 there appears to be uniform spread of contrast across the epidural space (red arrows), with no evidence of a transverse septum. There is a high posterior contrast column up to T5. Retrograde flow of contrast is seen around the lower (red) catheter to the erector spinae muscles (blue arrow), and this partly obscures the mass of epidural contrast. Contrast leakage to the skin is evident (X). The upper catheter is not visible. (d) Diagram of septal anatomy and presumed position of the catheter tip (O), on the left side of the epidural space, in the same patient.

Figure 7.4

(a) Anteroposterior (AP) epidurogram showing predominantly left-sided spread of contrast (T5 to L5, arrowed) from a centrally placed catheter tip, almost certainly caused by a midline septum. The attenuated right-sided contrast only extends from T11 to L3. (b) Lateral epidurogram following unilateral block, with uniform spread of contrast across the lumbar epidural space (from T12 to L5, arrowed), suggesting a midline septum with no lateral extensions.

Figure 7.5

(a) Anteroposterior (AP) epidurogram with catheter-tip at L2–3 and almost totally left-sided spread of contrast from L1 to L5 and profuse left foraminal spill (arrowed). Appearances suggestive of a midline septum. (b) Lateral epidurogram following unilateral block. There is a restricted spread of contrast from L1 to L5, with a pronounced posterior column of epidural contrast containing air bubbles. The attenuated anterior column of contrast is separated by a central filling defect (arrowed), suggesting the presence of a transverse septum in addition to the midline septum. (c) Diagram of septal anatomy and presumed position of catheter tip (O) in the left posterior dorsolateral space. (d) A three-dimensional model of the unilateral mass of contrast (oblique view) showing profuse left-sided foraminal spill.

Figure 7.6

(a) Anteroposterior (AP) epidurogram with predominantly right-sided contrast spread from L1 to S1 (arrowed), with prominent right foraminal spill and a straight medial border between L3 and S1. Appearances suggest a midline septum. (b) Lateral epidurogram in the same patient, with marked anterior and posterior columns of contrast from L5 to S1, enclosing a large filling defect (arrowed), suggesting a transverse septum, in addition to a midline septum. (c) Diagram of septal anatomy and presumed position of catheter tip (O) in the right posterior dorsolateral space.

Figure 7.7

(a) Anteroposterior (AP) epidurogram showing fairly extensive contrast spread from T5 to S1, with a dense collection from T11 to L2 (arrowed), which has characteristic scalloped edges and suggests a posterior distribution of contrast. There is minimal foraminal spill. (b) Lateral epidurogram confirming the predominantly posterior distribution of contrast (blue arrows), with absent anterior column and multiple filling defects (red arrows) containing air bubbles and only sparse contrast. Combined images suggest the presence of a transverse septum. (c) Diagram of septal anatomy and presumed position of the catheter tip (O) in the posterior dorsolateral space.

Figure 7.8

(a) Anteroposterior (AP) epidurogram showing a dense collection of contrast from L1 to L4 (arrowed), with characteristic scalloped edges and minimal foraminal spill, predominantly at the back of the epidural space. (b) Lateral epidurogram confirming the predominantly posterior distribution of contrast (blue arrows), with very attenuated anterior column and large filling defect (red arrows) containing air bubbles in a sparse mass of contrast. The combined images suggest the presence of a transverse septum.

Figure 7.9

(a) Anteroposterior (AP) epidurogram revealing catheter tip pointing caudally, with extensive but narrow spread of contrast in a characteristic 'fusiform' shape suggestive of posterior distribution, from T5 to L5 (arrows), with a smooth outline and containing air bubbles. (b) Lateral epidurogram confirming the predominantly posterior distribution of contrast (blue arrows), with only a very attenuated anterior column, at L2, and a large filling defect (red arrows) containing air bubbles and sparse contrast. Combined images suggest the presence of a transverse septum, at the very back of the epidural space. (c) Diagram of septal anatomy and presumed position of catheter tip (O) in the posterior dorsolateral space, with no midline septum.

Figure 8.1

Anteroposterior (AP) radiograph (from 1974) used for pelvimetry. Severe kyphoscoliosis is noted, and the presence of a term foetal head in utero.

Figure 8.2

(a) Anteroposterior (AP) radiograph of familial scoliosis with Harrington rod instrumentation, upper view. (b) An AP radiograph of familial scoliosis with Harrington rod instrumentation, lower view, with presence of spina bifida occulta (SBO) at S1.

Figure 8.3

(a) Anteroposterior (AP) epidurogram with mild scoliosis. The contrast is predominantly right-sided from T10 to S1 with profuse right-sided transforaminal spill (arrowed) and only patchy left-sided contrast from T10 to L2. (b) Lateral epidurogram showing a loss of lumbar lordosis, with patchy spread of contrast across the lower thoracolumbar epidural space (arrowed).

Figure 8.4

(a) Anteroposterior (AP) epidurogram with mild scoliosis. The contrast appears to be totally right-sided, from T10 to L5, (arrowed) with right-sided transforaminal spill. (b) Lateral epidurogram showing an increased lumbar lordosis. There is faint, but fairly uniform spread of contrast across the lumbar epidural space (arrowed), but the anterior column of contrast does not extend above L2.

Figure 8.5

(a) Anteroposterior (AP) epidurogram with mild scoliosis. The contrast is mostly right-sided from T8 to L5 with a fairly straight midline border. There is profuse right-sided transforaminal spill (red arrows). Sparse left-sided contrast spread from T10 to L3 is present, with a narrow lateral column (blue arrows). (b) Lateral epidurogram in the presence of scoliosis. There is a uniform spread of contrast across the lumbar epidural space (arrowed), with an extensive posterior column above.

Figure 8.6

(a) Anteroposterior (AP) epidurogram in an elderly patient with severe kyphosis. There is extensive but patchy spread of contrast from T2 to L5, with extensive transforaminal spill, which has an unusual 'cauliflower' appearance at several levels (arrowed). (b) Upper lateral epidurogram showing the severe kyphotic curve, with a very high posterior column of contrast (arrowed), extending to T2.

Figure 8.7

Lateral magnetic resonance imaging (MRI) scan of lumbar spine showing uncorrected spondylolisthesis with marked anterior displacement of L5 on S1 (arrows). Epidural block at L2–3 was satisfactory.

Figure 8.8

(a) Anteroposterior (AP) radiograph following spinal fusion for L5–S1 spondylolisthesis. Below L1, vertebral anatomy is grossly distorted, with bone grafts and new bone formation (arrowed). (b) Lateral radiograph following spinal fusion for L5–S1 spondylolisthesis. Marked lumbar lordosis and acute sacral angulation are evident, in addition to the fusion of L4 to S1, with bone grafts and new bone formation (arrowed). (c) An AP epidurogram following 6mL of contrast. The catheter tip was seen at the T9–10 interspace, with contrast extending down to T10–11 on the left (arrowed). (d) Lateral epidurogram following 6mL of contrast. Contrast spread is fairly uniform between T5 and T11.

Figure 8.9

(a) Anteroposterior (AP) radiograph showing scoliosis and Harrington rods, with the lumbar curve convex to the left, and the catheter tip at L2–3, to the right of the midline. (b) An AP epidurogram (magnified) showing predominantly right-sided distribution of contrast, from L1 to L5 (blue arrows), with marked right transforaminal spill (red arrows). (c) Lateral epidurogram revealing the lower end of a Harrington rod with a loss of lumbar lordosis and contrast flowing fairly uniformly across (the right side of) the epidural space from L1 to L5.

Figure 8.10

(a) Anteroposterior (AP) epidurogram revealing laminectomies at L3, L4 and L5 with screw fixation at L4–5.The body of contrast extends from T8 to an abrupt cut-off at L2 (lower arrow) and is a little fragmented. The only significant foraminal spill is at L1 and L2. (b) Lateral epidurogram post-laminectomy. The epidural space appears disrupted below L2 (lower arrow), with an irregular edge to the contrast, suggesting a fibrous reaction.

Figure 8.11

(a) Anteroposterior (AP) radiograph of congenital lumbar block vertebrae. (b) Lateral radiograph of congenital lumbar block vertebrae, with relatively wide vertebral canal (arrowed).

Figure 8.12

Anteroposterior (AP) radiograph of L5 and S1 spina bifida (arrowed). Epidural block was satisfactory.

Figure 8.13

Anteroposterior (AP) radiograph of S1 spina bifida (arrowed). Epidural block was satisfactory.

Figure 8.14

Anteroposterior (AP) radiograph showing congenital lumbar hemivertebrae and spina bifida at S1 (arrowed). No regional block required.

Figure 8.15

Outcome of epidural blocks in 18 parturients with spinal dysraphism.

Figure 8.16

Anteroposterior (AP) epidurogram (magnified) showing spina bifida occulta at S1 (red arrow), in the presence of the caudal end of a mass of intradural contrast (blue arrow). Same patient as in Fig. 5.14b, p.61.

Figure 8.17

Anteroposterior (AP) epidurogram showing spina bifida occulta at S1(red arrow), with transforaminal spill of epidural contrast (blue arrows) and dense intradural contrast (yellow arrow).

Figure 8.18

Anteroposterior (AP) epidurogram of lumbar spine showing mild scoliosis with spina bifida occulta at S1 (arrowed), and fairly typical epidural contrast spread following a high block.

Figure 8.19

Anteroposterior (AP) epidurogram showing spina bifida occulta at S1 (lower arrow), associated with predominantly left-sided contrast (upper arrows) following unilateral block, almost certainly caused by a midline septum.

Figure 8.20

Anteroposterior (AP) radiograph (magnified) of lumbosacral junction showing spina bifida occulta at S1 (arrowed), following a persistent predominantly left unilateral block.

Figure 8.21

Anteroposterior (AP) epidurogram showing spina bifida occulta at S1 (lower arrow), with restricted spread of epidural contrast from T12 to L4, following a 'missed segment block' with persistent right sided T10–11 abdominal pain during labour. The spread of contrast is abruptly cut off at L1 on the right (upper arrow).

Figure 8.22

(a) Anteroposterior (AP) epidurogram, showing pars interarticularis defects at L5 (blue arrows) and spina bifida occulta at S1 (lower red arrow), with a restricted caudal spread of epidural contrast to L3 only (upper arrows) following a poor block of sacral nerve roots. (b) An AP epidurogram providing a close-up view of pars interarticularis defects at L5 (blue arrows) and spina bifida occulta at S1 (red arrow).

Figure 8.23

(a) View of patient's back with prominent midline mole at L2 (arrowed), and multiple puncture marks at L3–4. (b) Anteroposterior (AP) radiograph demonstrating spina bifida at S1, in the same patient.

Figure 8.24

(a) Photograph of lower back and buttocks with the patient in the left lateral position, showing the opening of a dermal sinus tract on the right side of the coccyx (arrowed). This is associated with six unsatisfactory epidural blocks in four labours and spina bifida occulta at S1/S2. (b) Anteroposterior (AP) radiograph in same patient showing spina bifida in the form of a V-shaped defect (arrowed), resulting from failure of fusion of the posterior elements of S1 and S2.

Figure 8.25

(a) View of patient's back with dermal sinus tract, presenting as a dimple at L4–5. (b) Close-up view of dimple, with raised cystic mass and punctum. (c) Anteroposterior (AP) radiograph of the same patient, with spina bifida at S1, and associated distortion of L5.

Figure 9.1

Intact Braun flexible tip catheter on the left, with absent tip on the right, following removal from patient.

Figure 9.2

The three models of Portex epidural catheter used in this work, with variable eye spacings (from left to right): the closer eye, intermediate and standard catheters.

Figure 9.3

(a) Anteroposterior (AP) epidurogram following failed block for caesarean section. There is a large, predominantly right-sided, filling defect at L1–2 (arrowed). (b) Lateral epidurogram showing attenuation of the posterior column of contrast (between the arrows) at the level of the filling defect. (c) The blocked catheter, with obstructive debris or 'swarf' (arrowed).

Figure 9.4

A view of the distal end of a 'ribbed' Perisafe catheter (Becton Dickinson) showing the unique irregular lumen.

Figure 9.5

Anteroposterior (AP) epidurogram showing a mild degree of scoliosis with a ribbed Perisafe catheter inserted at L2–3 to the right of the midline, deviating laterally and escaping through the L2–3 foramen, and contrast collecting anterior to the psoas muscle (arrowed).

Figure 9.6

Anteroposterior (AP) epidurogram showing a Perisafe ribbed catheter inserted at L3–4 in the midline, and running laterally to the right. Contrast injection (7mL) flowed into a narrow right lateral epidural column between L2 and L4 (arrowed) with transforaminal spill only at the L2–3 foramen.

Figure 9.7

Direction of catheter travel.

Figure 9.8

(a) Anteroposterior (AP) epidurogram through a laterally placed catheter tip (closer eye). Contrast is seen from L1 to L5, more densely on the left, following a persistent left unilateral block. Transforaminal spill of contrast (arrowed) is also far more prolific on the left. (b) Lateral epidurogram, showing a fairly uniform spread of contrast across the epidural space from T12 to L5 (arrowed). The combined views suggest the presence of a midline septum associated with lateral placement of the catheter tip.

Figure 9.9

Anteroposterior (AP) radiograph of thoracolumbar spine showing a radio-opaque 19 gauge flexible-tip catheter (Arrow) running caudally, despite cephalad insertion (see Fig. 7.9a, p.96).

Figure 9.10

(a) Anteroposterior (AP) epidurogram revealing a 19 gauge catheter (Portex) running caudally, despite cephalad insertion, with fairly extensive vertical spread of contrast from T10 to L4 (arrowed) but only minimal transforaminal spill at L3–4, following a successful block. (b) Lateral epidurogram showing the caudal direction of the catheter, with fairly extensive and uniform spread of contrast (arrowed) but with an attenuated anterior column above L2.