CLINICAL REPORT

Lumbar plexopathy after abdominal hysterectomy. Case report^*

Plexopatía lumbar después de la histerectomía abdominal. Relato de caso

Elizabeth Vaz da Silva, TSA^I; Marco Antonio Cardoso de Resende, TSA^II; Alberto Pantoja, TSA^III; Adriana Barrozo Ribeiro Furuguem Carvalho^IV; Alexandre Barbosa da Silva^V, Fabrício Azevedo Cardoso^VI

^IResponsável pelo CET HUAP/UFF; Professora Adjunta do Departamento de Cirurgia Geral e Especializada do HUAP/UFF
^IIInstrutor do CET/SBA do HUAP/UFF
^IIIAnestesiologista do HUAP/UFF
^IVEx-Membro do Serviço de Anestesiologia do HUAP/UFF Anestesiologista do Hospital Geral de Bonsucesso
^VME₂ da CNRM do HUAP/UFF
^VIME₃ da CNRM do HUAP/UFF

Correspondence to

SUMMARY

BACKGROUND AND OBJECTIVES: Very often, neurological injuries diagnosed postoperatively are attributed to the anesthesia, but they can also be secondary to the surgery itself. The aim of this report was to present the case of a patient who underwent a pelvic surgery and developed lumbar plexopathy, and to discuss the possible causes.
CASE REPORT: A woman patient, 38 years old, 58 kg, 1.63 m, physical status ASA I, was admitted to undergo a total abdominal hysterectomy for treatment of uterine leiomyomatosis. Initial monitoring included pulse oxymetry, non-invasive blood pressure, electrocardioscope, and urine output. After venous cannulation in the left upper limb with an 18G catheter, cefazoline (2 g), dypirone (2 g), dexamethasone (10 mg), and metochlopramide (10 mg) were administered. With the patient in left lateral decubitus, a 16G Tuohy needle was inserted in the L₃-L₄ space, in the median line, for the epidural block. Fifteen milliliters of 0.75% ropivacaine and 2 mg of morphine were administered, followed by placement of the catheter for postoperative analgesia. The surgery was uneventful, and the patient's cardiovascular parameters were stable. Eight hours after the procedure, at the postanesthetic follow-up, the patient could not walk and presented monoparesis in the left lower limb. The hypothesis of radicular syndrome was ruled out after clinical and radiological evaluation. Since symptoms did not resolve, an electroneuromyography was done 30 days later, and was compatible with lumbar plexopathy, which was possibly caused by trauma.
CONCLUSIONS: The anesthesiologist must be aware of the postoperative neurological complications and should be part of the efforts to diagnose their causes, of the treatment, and its evolution.

Key Words: ANESTHETIC TECHNIQUES, Regional: continuous epidural; COMPLICATIONS, Neurologic: lumbar plexopathy.

RESUMEN

JUSTIFICATIVA Y OBJETIVOS: Las lesiones neurológicas diagnosticadas en el período postoperatorio muchas veces se atribuyen al acto anestésico, aunque puedan también decorrer del acto quirúrgico. El objetivo de este relato fue presentar el caso de una paciente sometida a la intervención quirúrgica pélvica que evolucionó con un cuadro de plexopatía lumbar y discutir las posibles causas.
RELATO DEL CASO: Paciente del sexo femenino, 38 años, 58 kg, 1,63 m de altura, estado físico ASA I, internada para tratamiento de leiomiomatosis uterina, con indicación de histerectomía total abdominal. La monitorización inicial incluyó oxímetro de pulso, presión arterial no invasiva, electrocardioscopio y diuresis. Después de la punción venosa en el miembro superior izquierdo con catéter 18G, fueron administrados, por vía venosa, cefazolina (2 g), dipirona (2 g), dexametasona (10 mg) y metoclopramida (10 mg). La anestesia peridural fue realizada con aguja Tuohy 16G, en el espacio L₃-L₄, en la línea mediana con la paciente en decúbito lateral izquierdo. Fueron administrados 15 mL de ropivacaína a 0,75% y 2 mg de morfina, a continuación posicionado catéter para analgesia postoperatoria. La intervención quirúrgica no tuvo intercurrencia, manteniendo a la paciente estable bajo el punto de vista cardiovascular. En la visita posanestésica, 8 horas después del procedimiento, la paciente no deambulaba y presentaba monoparesia en el miembro inferior izquierdo. Después de las investigaciones clínicas y radiológicas fue descartada la hipótesis diagnóstica de síndrome radicular. Al no haber regresión del cuadro, 30 días después fue realizada una electroneuromiografía que quedo compatible con plexopatía lumbar de posible origen traumática.
CONCLUSIONES: El anestesiólogo debe estar atento a las complicaciones neurológicas que puedan surgir en el postoperatorio, participando de la elucidación de las causas, del tratamiento y de su evolución.

INTRODUCTION

Severe neurological complications have been described after regional block. Postoperative neuropathies are frequently attributed to the anesthesia; however, it may also be secondary to the surgery itself.

Plexopathies and neuropathies are secondary to anesthetic blocks, and can be caused by intraneural injection ¹, hematoma ^2,3, mispositioning ⁴ and local neuritis.

Lesions in the femoral, lateral femoral cutaneous, and obturator nerves, although rare, do occur after pelvic surgeries, and trauma is the most frequent mechanism. Femoral nerve lesion is reported in the literature associated with several surgical procedures, such as inguinal herniorrhaphy, total hip arthroplasty, gynecological surgeries, and intra-abdominal vascular surgeries, and, less often, with appendectomy, lumbar sympathectomy, and laparoscopies ⁵. The objective of this report was to present the case of a patient who underwent total abdominal hysterectomy and went on to develop plexopathy, and to discuss the probable causes.

CASE REPORT

A woman patient, 38 years old, 58 kg, 1.63 m, physical status ASA I, was admitted to the hospital for a total abdominal hysterectomy for uterine leiomyomata.

Premedication included midazolam 7.5 mg PO at 10 p.m., the night before the surgery, and at 7 a.m., i.e., one hour before the surgery.

Monitoring included pulse oxymetry, non-invasive blood pressure, electrocardioscope in the D_II derivation, and urine output. Ringer's lactate was administered after venous cannulation with an 18G catheter in the left upper limb.

The patient was placed on left lateral decubitus and epidural puncture was done with a 16G Tuohy needle in the median line in the L₃-L₄ space. The epidural space was identified by the loss of resistance technique. After making sure there was no blood or cerebrospinal fluid return, a test dose of 3 mL of 2% lidocaine (60 mg) with adrenaline 1:200.000 followed by 15 mL of 0.75% ropivacaine with 2 mg morphine were administered. A catheter for postoperative analgesia was then placed. Twenty minutes after the epidural block, the maximum sensitive blockade obtained was in T₄.

Cefazoline (2 g), dypirone (2 g), dexamethasone (10 mg), and metochlopramide (10 mg) were administered in the beginning of the procedure, and ephedrine (2 mg) 15 minutes after the block, when there was a 30% drop in blood pressure.

There were no complications during the surgery, which lasted 160 minutes, and the patient was transferred to the posthanestetic recovery unit.

Eight hours after the procedure, the patient could not ambulate and developed monoparesis in the left lower limb.

She was evaluated by the Neurology service, being diagnosed with a probable radicular syndrome. On physical exam, she presented paresthesia in the upper left thigh, lateral and anterior aspect of the left thigh, patellar reflex absent on the left, Achilles reflex present and equal bilaterally.

X-rays of the lumbosacral spine and abdomen did not show any abnormalities; CT scan of the lumbosacral spine was normal.

The patient's signs and symptoms remained the same and, 30 days after the surgery, an electroneuromyography was done. It showed a normal nervous conduction, the needle exam showed positive waves and fibrillation of the left quadriceps and left adductor muscles, suggesting the diagnosis of lumbar plexopathy.

DISCUSSION

The lumbar plexus is formed by the nervous roots of T₁₂ to L₄ ^6,7. The femoral, lateral femoral cutaneous, and obturator nerves are formed by the superior roots of L₂-L₃-L₄, being responsible for the sensitive-motor innervation of the thigh ⁸. In the pelvis, the femoral nerve emerges from the major psoas muscle, descending deep within the iliac fascia. The femoral nerve ends 4 cm below the inguinal ligament; behind this ligament, the anterior branch gives rise to the medial cutaneous nerve of the thigh and the intermediate cutaneous nerve that innervate the anteromedial aspect of the thigh down to the knee. The posterior branch of the femoral nerve innervates the quadriceps femoris and sartorius muscles. The saphenous nerve represents the terminal branch that innervates the skin of the medial aspect of the leg down to the medial portion of the foot ⁷. The femoral cutaneous nerve migrates laterally, running under the inguinal ligament close to the anterosuperior iliac spine. The obturator nerve, the third branch of the lumbar plexus, runs medially and posteriorly in the pelvis; when it emerges from the obturator foramen, it provides sensitive-motor fibers to the medial portion of the thigh and medial aspect of the knee ⁸.

The neurophysiological study has interpretative limitations in radiculopaties. It might be difficult to differentiate, for example, L₂-L₃ or L₄ radiculopathy from lumbar plexopathy or femoral neuropathy because the innervation of the thigh muscles by these three nerve roots overlaps ⁹. In 1933, Pollock ¹⁰ stated that the paralysis of the femoral nerve is rarely caused by gynecological disease and that such lesion would happen after gynecological surgeries, resulting from trauma and adhesions. Until that publication only four cases of paresis of the femoral nerve associated with gynecological surgeries had been reported.

In 1958, Winkelman and Johnson ^11,12 reported paresis of the femoral nerve, isolated or combined with paresis of the obturator nerve, in surgical procedures with rotation, abduction and internal flexion of the lower limbs. The neuritis affecting isolated nerves after surgeries would be caused by ischemia or a mechanical factor, such as compression, stretching, or direct trauma ¹³. Four degrees of lesions were described: (1) no effects; (2) paralysis with fast recovery due to release of pressure; (3) paralysis with slow recovery without degeneration; and (4) anatomical lesion with degeneration ¹⁴.

A prospective study by Kvist-Poulsen and Borel ¹⁵ showed that the lesion of the femoral nerve after abdominal hysterectomy is much more frequent than indicated in the literature, with an incidence between 7.45% and 11.6%. This high incidence suggests that many cases of milder lesion of the femoral nerve might not be diagnosed due to the short duration of the symptoms or lack of knowledge about this complication. Fifteen of 17 patients studied had spontaneous recovery and only two had residual sensitive disturbances, without more serious changes.

Most cases reported in the literature had spontaneous recovery within one to six months, but one case had loss of sensitivity and motor dysfunction ¹³.

As a rule, there are sensitivity changes in cases of neuropathy of the obturator nerve, but there might be motor dysfunction of the adductor muscles of the thigh. The neuropathy of the lateral femoral cutaneous nerve is usually temporary since, unlike the other two nerves, it is only sensitive ¹⁶.

A British prospective study with 100 patients who underwent total abdominal hysterectomy tried to analyze the disparity between the reported incidence by Kvist-Poulsen and Borel and the real incidence, since there was only one case in the United Kingdom. Seven patients presented clinical evidence of nerve lesion, and the investigation demonstrated there was a lesion of the lateral femoral cutaneous nerve, at the level of the Balfour retractor, in six patients as a complication of the surgery ¹⁷.

Static retractors, by exerting continuous pressure on the ileopsoas muscle, stretch the femoral nerve, making it ischemic by occlusion of the external iliac artery or compressing blood vessels closely related to the nerve when going through the muscle. The obturator nerve can be stretched or squeezed by retractors placed deeply in the pelvic floor. Excessive abduction of the thigh can stretch the obturator nerve. There can also be direct pressure over the lateral femoral cutaneous nerve, since its trajectory varies. Small branches of this nerve can puncture the inguinal ligament, and the hyperflexion of the thigh over the abdomen can increase the pressure on the ligament ¹⁶.

There are three predisposing factors for the lesion: Plannenstiel incision, slender build, and the need to apply greater pressure on the retractors used to better expose the surgical field, causing direct nerve compression ^7,13,17,18. The neuromuscular blockade and inadequate positioning of the patient also contribute to the pathogenesis ^4,16. However, some studies indicate that the following factors cannot be considered specific pathogenic factors: surgical technique, pelvic disease, type of incision, and the surgeon's technical ability ^15,18.

Most neuropathies of the lower limbs are symptomatic shortly after regression of the anesthesia. The opposite is seen in the upper limbs, where the symptoms of lesion of the ulnar nerve, the most frequent, have a late beginning in 62% of the cases ²⁰.

Peripheral nerve lesion related to epidural anesthesia has a prevalence of 0.1%, for the transitory lesion, and 0.02%, for the permanent lesion, and is usually associated with diluents and addictives in the solution of the local anesthetic ^18,21-23.

Although a peripheral nerve lesion is often attributed to the anesthesia, it can have other causes, such as mechanical trauma associated with the surgical instruments. It is important to emphasize the importance of the postanesthetic follow-up as well as of the diagnosis of this unusual complication of pelvic surgeries. Nowadays, this follow-up is an integral part of the anesthesiologists' defense in face of possible medical-legal suits.

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Correspondence to:
Dr. Marco Antonio Cardoso de Resende
Av. 7 de Setembro, 91/1501 — Icaraí
24230-250 Niterói, RJ
E-mail: macresende@ig.com.br

Submitted for publication 31 de janeiro de 2006
Accepted for publication 25 de julho de 2006

* Received from Serviço de Anestesiologia do Hospital Universitário Antônio Pedro da Universidade Federal Fluminense (HUAP/UFF), Niterói, RJ