Ipsilateral thoraco-lumbar anaesthesia and paravertebral spread after low thoracic paravertebral injection

M. K. Karmakar, T. Gin and A. M.-H. Ho

Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, NT, Hong Kong, People’s Republic of China*Corresponding author

Accepted for publication March 19, 2001


    Abstract
 Top
 Abstract
 Introduction
 Case report
 Discussion
 References
 
We report ipsilateral thoraco-lumbar anaesthesia and paravertebral spread of contrast after injection through a thoracic paravertebral catheter that was placed at the right T8–9 spinal level for pain management in a patient with multiple fractured ribs. We review the literature and describe the subendothoracic fascial communication between the thoracic paravertebral space and the retroperitoneal lumbar paravertebral region, which we propose, is the anatomical basis for ipsilateral thoraco-lumbar anaesthesia and paravertebral spread of contrast in our patient.

Br J Anaesth 2001; 87: 312–16

Keywords: anaesthetic techniques, regional, paravertebral; anatomy, endothoracic, retroperitoneal, paravertebral space


    Introduction
 Top
 Abstract
 Introduction
 Case report
 Discussion
 References
 
Thoracic paravertebral injection of local anaesthetic produces ipsilateral somatic and sympathetic nerve blockade in multiple contiguous thoracic dermatomes above and below the site of injection.1 The origin of the psoas major muscle is described to completely seal off the thoracic paravertebral space below the level of the 12th thoracic vertebra2 and caudal spread of a thoracic paravertebral injection below this level through the paravertebral space is thought to be unlikely.2 Clinical ipsilateral thoraco-lumbar anaesthesia has occasionally been described,1 35 challenging the concept of lumbar nerve sparing following thoracic paravertebral block.2 To resolve this controversy, Saito et al. recently performed a cadaveric study and demonstrated ipsilateral spread of coloured dye from the thoracic paraverterbal space to the retroperitoneal lumbar paravertebral region.6 Dye was seen to spread in the endothoracic fascia of the thorax and extend into the abdomen through the medial and lateral arcuate ligaments to involve the fascia transversalis and the lumbar spinal nerves.6 However, the fascial communications between the thoracic paravertebral space and the retroperitoneal lumbar paravertebral region were not discussed in this report6 and the authors state that ‘the actual fluid communications between the endothoracic and transversalis fascias is not well-known’.6 Thus the fascial communication between the thoracic paravertebral space and the retroperitoneal space still remains unexplained. In this report we describe ipsilateral thoraco-lumbar anaesthesia and paravertebral spread of contrast in vivo and review the fascial communications between the lower thoracic paravertebral space and the retroperitoneal space to account for this spread.


    Case report
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 Abstract
 Introduction
 Case report
 Discussion
 References
 
A 63-year-old previously healthy man, weighing 60 kg was referred to our pain team for management of right-sided fractured ribs, which had compromised his ability to breathe deeply and cough effectively. Pain was rated as severe by the patient with a visual analogue score (VAS: 0 – no pain and 100 – worst imaginable pain) of 80 at rest and 100 on coughing. Oxygen saturation was 96% with PaO2 7.8 kPa and PaCO2 4.4 kPa breathing room air. A chest radiograph demonstrated fractured right 8–10th ribs with no pneumothorax or haemothorax. After informed consent, a right-sided thoracic paravertebral block was performed at the level of T7–8 with the patient in the sitting position using a 16-gauge Tuohy needle (Minipack, Portex, UK) according to the technique described by Eason and Wyatt,7 and 3 cm of the catheter was inserted into the paravertebral space. With the catheter safely secured to the back, the patient was returned to the supine position. After negative aspiration of the catheter for blood and CSF, 18 ml of 0.5% bupivacaine with 1:200 000 epinephrine was administered in small aliquots over a 3-min period. The patient soon became pain free. Thirty minutes following the paravertebral injection, the VAS for pain was 0 at rest and 20 on coughing, and ipsilateral anaesthesia to temperature (cold) was elicited from the T7–T10 dermatomes with no contralateral extension. A continuous infusion of bupivacaine 0.25% was commenced at 7 ml h–1 and regular oral diclofenac 75 mg twice daily was also prescribed. The patient remained comfortable, was able to breathe deeply, complied with chest physiotherapy and was soon mobilized. On the second day after the thoracic paravertebral catheter placement, it was noted that the patient was having increasing pain (VAS: 30 at rest and 70 on coughing). On clinical examination there was no demonstrable cutaneous anaesthesia over the chest or abdomen and on inspection of the catheter insertion site it was apparent that the catheter had dislodged out of the thoracic paravertebral space.

After discussion with the patient, he requested to have the thoracic paravertebral catheter resited. Using the same technique the right thoracic paravertebral space was accessed one interspace lower at the T8–9 level and 3 cm of catheter was inserted into the thoracic paravertebral space. The catheter was tunneled subcutaneously and safely secured to the back. A total of 10 ml of 0.5% bupivacaine with 1:200 000 epinephrine was injected via the catheter over a 2-min period with the patient in the supine position. The patient once again became pain free. Thirty minutes following the injection, the VAS was 0 at rest and 20 on coughing and ipsilateral cutaneous anaesthesia to temperature (cold) was elicited from T7–L3 dermatomes. There were no significant haemodynamic changes or evidence of motor blockade in the distribution of the lumbar spinal nerves bilaterally as judged by normal hip flexion, knee extension and hip adduction.

To confirm the position of the catheter and demonstrate the spread of the paravertebral injection 10 ml of Iopamiro-300 (Iopamidol-300 mg ml–1, Bracco s.p.a., Milano, Italia) was injected via the indwelling paravertebral catheter distal to the bacterial filter. Immediately following this injection an anteroposterior chest x-ray was taken (Fig. 1). Ipsilateral paravertebral spread of contrast from the ninth thoracic to the second lumbar segment below the diaphragm was noted on the chest x-ray (Fig. 1).



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Fig 1 Chest x-ray (anteroposterior view) after injection of contrast through the paravertebral catheter. Note ipsilateral thoraco-lumbar paravertebral spread from T10 to L2.

 

    Discussion
 Top
 Abstract
 Introduction
 Case report
 Discussion
 References
 
Thoracic paravertebral injection of local anesthetic produces ipsilateral somatic and sympathetic nerve blockade in multiple thoracic dermatomes above and below the site of injection.1 This results from spread to the contiguous thoracic paravertebral space,810 the intercostal space laterally810 and the epidural space medially.8 9 11 The thoracic paravertebral injection in our patient also produced multidermatomal ipsilateral thoracic anaesthesia, which was effective in relieving pain caused by the multiple fractured ribs. However after the second paravertebral injection we observed ipsilateral thoraco-lumbar anaesthesia extending from T7 to L3 dermatomes with no motor involvement of the lumbar spinal nerves. The post-contrast chest x-ray also demonstrates ipsilateral thoraco-lumbar (T9–L2) paravertebral spread of contrast (Fig. 1).

There is controversy whether low thoracic paravertebral block can extend into the lumbar region. Lönnqvist and Hildingsson examined the caudal limit of the thoracic paravertebral space in eviscerated cadavers by approaching the thoracic paravertebral space internally from the thoracic cavity.2 Based on observations made after probing and dye injection, they concluded that the origin of the psoas major muscle completely sealed off the thoracic paravertebral space below the level of the 12th thoracic vertebra, and proposed that spread of a thoracic paravertebral block below this level through the paravertebral space was unlikely.2 However ipsilateral thoraco-lumbar anaesthesia,1 35 radiological spread of contrast below the diaphragm9 and thoraco-lumbar spread of coloured dye in cadavers6 has been described,1 46 9 challenging the concept of lumbar nerve sparing following thoracic paravertebral block.2

The incidence of ipsilateral thoraco-lumbar anaesthesia after thoracic paravertebral block is not known but published data suggest that it is more common after low thoracic paravertebral injections.1 35 Richardson et al. report ipsilateral L1 spinal nerve involvement in three of the ten patient studied after paravertebral injection of 1.5 mg kg–1 bupivacaine 0.5% at T6 and T10 level respectively.3 Cheema et al. performed paravertebral injections at a mean level of T9–10 (range T7–8 to T10–11) and report mean ipsilateral anaesthesia of five dermatomes (range 1–8), with upper and lower limits of T6 and L3, after 15 ml of bupivacaine 0.5%.1 Saito et al. report ‘broad unilateral anaesthesia’ extending from the left T4 to L3 after injection of local anesthetic through an epidural catheter, which was inadvertently inserted in the left T11 paravertebral space.5 More recently, Saito et al., in a cadaveric study, demonstrated ipsilateral retroperitoneal lumbar paravertebral spread of crimson dye along the endothoracic fascia and fascia transversalis through the medial and lateral arcuate ligament, after thoracic paravertebral injection at T11.6 The dye stained the ipsilateral subcostal, iliohypogastric, ilioinguinal, genitofemoral and lateral femoral cutaneous nerve in all 12 cadavers studied, and in two cases the dye also reached the femoral nerve.6 On average, spread extended from the 6th intercostal nerve to the lateral femoral cutaneous nerve (T6–L2).6 All of these reports of ipsilateral thoraco-lumbar anaesthesia1 35 and paravertebral spread6 9 in vivo1 35 9 and in cadavers6 suggests that there is a fascial plane of communication between the ipsilateral thoracic paravertebral space and the retroperitoneal space. Review of the literature shows that such an anatomical plane of communication exists which may account for ipsilateral thoraco-lumbar anaesthesia.

The endothoracic fascia, also referred to as the ‘internal thoracic fascia’, is a fibroelastic structure that forms the deep fascia of the thorax and lines the internal surface of the intercostal muscle, the intervening ribs, and the diaphragm.12 At the diaphragm, the endothoracic fascia is very thin,6 13 being thinnest at the upper surface and thickest at its edges.6 Inferiorly the endothoracic fascia is continuous with the fascia transversalis (Fig. 2),6 12 13 which is the deep fascia of the abdomen. This continuity occurs dorsal to the diaphragm through the medial and lateral arcuate ligament (lumbo-costal arch) and the aortic hiatus.6 12 13 The fascia transversalis blends medially with the anterior layer of the quadratus lumborum fascia and the psoas fascia (psoas sheath) (Fig. 3).14 The subcostal (T12), iliohypogastric (L1) and ilioinguinal (L1) nerves course anterior to and in contact with the quadratus lumborum,15 while the genitofemoral nerve (L1, L2) descends on the ventral surface of the psoas major muscle and the lateral femoral cutaneous nerve (L2, L3) crosses the lateral border of the psoas muscle at the level of the inferior margin of L4 vertebra15 in this fascial plane.



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Fig 2 Saggital section showing the fascial relations of the lower thoracic paravertebral space and the retroperitoneal space.

 


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Fig 3 Anatomical relations of the fascia covering the psoas major, quadratus lumborum and fascia transversalis to the retroperitoneal space.

 
The fascia overlying the upper end of the psoas major muscle (psoas fascia) is thickened to form the medial arcuate ligament, which is attached medially to the body of L2 and laterally to the transverse process of L1.14 The psoas major muscle courses under this fascial arch, also referred to as the ‘open end of the psoas sheath’,14 to enter the posterior mediastinum and lie in contact with the lower thoracic vertebra and pleura.14 It is through this fascial arch that tuberculous suppuration of the lower thoracic spine is thought to enter the psoas sheath and present as an abscess in the retroperitoneum or groin.14 This may also be the route by which the genito-femoral nerve, which lies on the ventral surface of the psoas major muscle,15 is involved.6 Lönnqvist and Hildingsson, in their cadaver study, also observed passage of a guide wire or dye below the level of T12 in the fascial plane above the psoas muscle on two occasions, which the authors attributed to over-vigorous probing or injection,2 but may also be explained by the above mechanism.

Based on the fascial anatomy described, an injection in the lower thoracic paravertebral space posterior to the endothoracic fascia can spread caudally via the medial and lateral arcuate ligament to the retroperitoneal space in the abdomen.4 Since this results in spread anterior to the surface of the quadratus lumborum and psoas major muscle, the subcostal, iliohypogastric, ilioinguinal, genitofemoral and the lateral femoral cutaneous nerve may be involved.6 This is the anatomical basis of the technique of ‘extended unilateral anaesthesia’4 and may also be the mechanism involved in our patient.

In summary, this case report demonstrates that ipsilateral thoraco-lumbar anaesthesia and paravertebral spread can occur after low thoracic paravertebral injection. Based on current evidence and anatomical knowledge the mechanism for this observation is an extended subendothoracic fascial spread from the thoracic paravertebral space to the retroperitoneal space in relation to the anterior surface of the psoas major and quadratus lumborum muscle where it affects the lumbar spinal nerves. This may have clinical application in the management of acute and chronic pain of unilateral thoraco-lumbar origin.


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 Introduction
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 Discussion
 References
 
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