Article Text
Abstract
A 57-year-old man was diagnosed with acute myocardial infarction and Stanford type A aortic dissection that had spread to the common iliac arteries. He underwent a Bentall procedure for vascular repair. Immediately after surgery, he developed numbness and severe weakness in his left leg. On examination, he had hypotonia, absent deep tendon reflexes, weakness in the left leg (Medical Research Council (MRC) scale for muscle strength - 0/5 distal, 3/5 proximal) and reduced sensation in the left leg. Electromyography confirmed subacute involvement of the left lumbar and lumbosacral plexus. MR scan of the lumbar plexus showed diffuse muscle oedema involving the left gluteus maximus. We diagnosed ischaemic lumbosacral plexopathy secondary to extensive aorta dissection and internal iliac artery occlusion. We discuss the clinical features of ischaemic plexopathy and the diagnostic approach and review the vascular anatomy of the lumbosacral plexus.
- peripheral neuropathology
- vascular surgery
- anatomy
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All data relevant to the study are included in the article or uploaded as supplementary information.
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Case description
A 57-year-old man developed intense chest pain which had started with intense sweating 20 min before. He had systemic hypertension and a history of smoking. An ECG showed ST elevation corresponding to an inferior wall acute myocardial infarction. Cardiac catheterisation found no significant coronary artery lesions, but a CT angiogram of the chest identified a Stanford type A aortic dissection. This involved the brachiocephalic trunk, left common carotid artery, subclavian arteries, coeliac trunk and superior mesenteric artery, extending to the aortic bifurcation and right common iliac artery. There were filling defects in the left common carotid and superior mesenteric arteries and total occlusion of the left common iliac artery (figure 1).
He successfully underwent a Bentall procedure, comprising complete replacement of the aortic valve and ascending aorta under total cardiopulmonary bypass with cross-clamping of the aorta, distal to the aneurysm.1 As the anaesthesia wore off, he reported numbness and severe weakness in his left leg. There was no sphincter dysfunction at this stage or at follow-up and no subsequent sexual dysfunction. His left leg was hypotonic and weak: hip flexion 4/5, hip extension 2/5, knee extension 3/5, knee flexion 3/5, foot dorsiflexion, inversion, eversion, hallux extension and plantar flexion 0/5. Left knee and ankle tendon reflexes were absent and all sensory modalities were lost (figure 2, online supplemental file 1).
Supplementary video
Nerve conduction studies and electromyography (44 days after aortic repair) found diffuse involvement of the left lumbar and lumbosacral plexus. The sensory nerve action potentials of the sural, superficial peroneal and saphenous nerves and the compound muscle action potentials were all absent in the left lower limb. There was spontaneous activity (fibrillation potentials and positive sharp waves) in all muscles innervated by the left lumbar and lumbosacral plexus, except gluteus medius. He could not activate most of his left leg and thigh muscles. Needle electromyography identified slight muscle activation, with evidence of incipient denervation in the gluteus medius and quadriceps femoris (figure 3). MR scan of the lumbar plexus showed diffuse muscle oedema affecting the left gluteus muscles, but without significant changes in the lumbar roots or lumbosacral plexus (figure 4).
We diagnosed ischaemic plexopathy caused by left iliac artery occlusion. After 14 months of follow-up there was moderate improvement in his pain and muscle strength, with left hip flexion improving to 4/5, hip extension to 4/5, and knee extension and flexion to 4/5. Movement at the ankle remained 0/5.
Discussion
Aortic dissection is a medical emergency in which a tear in the intimal layer of the aorta allows blood to flow between the layers of the vessel.2 Major risk factors include hypertension, atherosclerosis, family history, rheumatological or infective diseases that cause vasculitis, genetic conditions such as Marfan’s syndrome, Ehlers-Danlos syndrome and Turner’s syndrome, and cardiac abnormalities such as bicuspid aortic valve and coarctation of the aorta.2 Acute aortic dissection typically causes prominent chest or abdominal pain, but may also cause neurological symptoms. Around 5%–15% of patients with an aortic dissection report no pain, and among these neurological complications may be the sole flagging signal/symptom.3
The main neurological manifestations of aortic dissection include ischaemic stroke, spinal cord ischaemia, peripheral nerve ischaemia and hypoxic encephalopathy. Lower limb weakness in the setting of aortic dissection more often results from spinal cord ischaemia, which was our initial hypothesis. However, monoparesis, absence of pyramidal signs, lack of bladder, bowel or sexual dysfunction, neurophysiological abnormalities, and the MR scan of the lumbar plexus led to the alternative diagnosis of ischaemic lumbosacral plexopathy.
The lumbosacral plexus is composed of the ventral rami of the L1–S4 nerve roots.1 It is divided into two sections: the upper lumbar plexus (L1–L4 nerve roots) and the lower lumbosacral plexus (L4–S4 nerve roots). Following each section, there are a series of nerves (table 1).
This patient had greater involvement of the lower lumbosacral plexus, as inferred from the more prominent impairment at distal lower limb muscle strength.
The blood supply of the plexus derives mainly from the internal iliac artery and its branches: the iliolumbar artery, superior gluteal artery, lateral sacral artery and inferior gluteal artery (figure 5). Neurological dysfunction results from hypoperfusion and/or interruption of blood flow in the arteries supplying the lumbosacral plexus. This patient had a severe arterial injury, causing thrombosis and interruption in blood flow in the main artery supplying the lumbosacral plexus: the internal iliac artery.
Plexus ischaemia may result from acute or chronic disruption of its vascular supply. Small case series have identified a peculiar clinical syndrome associated with chronic lumbosacral plexus ischaemia, comprising intermittent claudication, exercise-induced pain, paraesthesia and motor deficits. The most frequent causes are severe stenosis or occlusion of the supplying arteries from the lumbosacral plexus.4
Acute ischaemia of the lumbosacral plexus is rare, with most cases attributed to surgical procedures of the abdominal aorta. Lefebvre et al 5 described a bilateral ischaemic plexus lesion due to surgical treatment of aortoenteric fistulas. Gloviczki et al 6 reported nine patients with ischaemic complications of aortoiliac reconstruction, including one case of lumbosacral ischaemic plexopathy and eight cases of ischaemic myelopathy. Four had onset of neurological symptoms immediately after the surgical procedure, as in the case presented here. The authors noted that patients with plexus and/or root injuries showed better recovery than those with spinal cord injuries. Lefebvre et al 7 described a case of aorta dissection in which abdominal pain started almost simultaneously with the neurological symptoms from the plexopathy, without limb pain. This case therefore resembles the patient presented here, in that the insult was painless, which usually relates to selective damage of larger fibres. Chhetri et al 8 described aortoiliac occlusive disease leading to acute bilateral lumbosacral plexopathy, although most patients have unilateral symptoms. Abdelhamid et al 9 described ischaemic lumbosacral plexopathy starting immediately after an aortoiliac bypass and right femoral artery graft due to an abdominal aortic aneurysm.
These are all very relevant cases that show that neurological symptoms can start either after surgical procedures or after the aorta dissection itself. Furthermore, weakness or numbness can be unilateral or bilateral with an asymmetric presentation.
Finally, there are two important reports of lumbosacral plexopathy following vascular reconstruction due to kidney transplantation. Dhillon and Sarac10 described a man undergoing a dual kidney transplant, while Hefty et al 11 described four women with insulin-dependent diabetes mellitus who underwent the procedure, suggesting that diabetes increases the risk of plexopathy.
This difficult case highlights that ischaemic lumbosacral plexopathy is a rare cause of neurological dysfunction following surgical procedures involving the aorta. However, clinicians should consider this condition in patients with aortic dissection who develop acute-onset neurological deficits, after having ruled out spinal cord ischaemia.
Key points
Vascular lesions are a rare cause of lumbosacral plexopathy.
The blood supply of the lumbosacral plexus mostly derives from one blood vessel (the internal iliac artery); its occlusion/lesion leads to ischaemic plexopathy.
Risk factors for lumbosacral ischaemia include aorta dissection (and its surgical repair) and kidney transplantation.
Ischaemic lumbosacral plexopathy should be suspected in people with acute-onset lower limb neurological deficits, with or without local pain.
Further reading
Gaul C, Dietrich W, Erbguth FJ. Neurological symptoms in aortic dissection: a challenge for neurologists. Cerebrovasc Dis. 2008;26:1–83.
Wohlgemuth WA, Rottach KG, Stoehr M. Intermittent claudication due to ischaemia of the lumbosacral plexus. J Neurol Neurosurg Psychiatry. 1999;67:793–54.
Chhetri, S. K., Lekwuwa, G., Seriki, D., & Majeed, T. Majeed, T. (2013) Acute flaccid paraparesis secondary to bilateral ischaemic lumbosacral plexopathy. QJM, 106(5), 463–4658.
Data availability statement
All data relevant to the study are included in the article or uploaded as supplementary information.
Ethics statements
Patient consent for publication
Supplementary materials
Supplementary Data
This web only file has been produced by the BMJ Publishing Group from an electronic file supplied by the author(s) and has not been edited for content.
Footnotes
Contributors BGG, OGPB, JLP: conception of the project: conception, organisation and execution; manuscript: writing of the first draft and review and critique. RMA, DMCC, FMRF, PHRCB, MLE-B: conception of the project: conception, organisation and execution. TYTS: conception of the project: conception, organisation and execution; manuscript: review and critique.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Provenance and peer review Not commissioned. Externally peer reviewed by Kathryn Brennan, Glasgow, UK.
Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.
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