eMedicine Specialties > Physical Medicine and Rehabilitation > Plexopathy

Neoplastic Lumbosacral Plexopathy

Author: Rajesh R Yadav, MD, Assistant Professor, Section of Physical Medicine and Rehabilitation, MD Anderson Cancer Center, University of Texas at Houston
Contributor Information and Disclosures

Updated: Dec 4, 2008

Introduction

Background

Neoplastic lumbosacral plexopathy (NLP) is an infrequent complication associated with advanced systemic cancer due to local or regional progression of the primary tumor. NLP is characterized by significant pain and sensorimotor deficits.

Anatomically, the lumbosacral plexus consists of lumbar (L1-L4) and sacral (L5-S5) portions, which are connected by the lumbosacral trunk (L4-L5).The L1-L4 nerve roots transverse through psoas muscle and then coalesce into the lumbar plexus, which then divides into anterior and posterior divisions. The first 3 nerves (iliohypogastric, ilioinguinal, femoral) of the 7 major branches of lumbar plexus provide motor and sensory innervation to the abdominal wall. The next 3 nerves (lateral femoral cutaneous, femoral, obturator) innervate the anteromedial thigh. The femoral nerve terminates into the saphenous nerve, providing sensation along the medial aspect of the leg.

The sacral plexus also divides into anterior and posterior divisions, which further divide into various peripheral nerves that provide sensory motor innervation to the posterior hip girdle, thigh, and anterior and posterior leg. The 5 main nerves are the superior gluteal, inferior gluteal, posterior femoral cutaneous, sciatic, and pudendal nerves. The sciatic nerve divides into the common peroneal and tibial nerves in the thigh.

NLP associated with pelvic, abdominal, and retroperitoneal tumors often results in significant pain, sensory disturbance, weakness, and disability. Plexus involvement occurs as a result of tumor extension or invasion and heralds a progressive disease course. Plexopathy is part of the initial presentation of cancer in 15% of patients.

Related eMedicine topics:
Diabetic Lumbosacral Plexopathy
Radiation-Induced Lumbosacral Plexopathy

Pathophysiology

Lumbosacral plexus involvement occurs most commonly due to intra-abdominal tumor extension (73% of cases); it occurs less commonly with growth from metastases, lymph nodes, or bone structures. A tumor can invade the plexus directly or track along the connective tissue or epineurium of nerve trunks.

The most prevalent types of tumors are colorectal tumors (20%), sarcomas (16%), breast tumors (11%), lymphoma (9%), and cervical tumors (9%). Other tumors, including multiple myeloma, account for another 37% of cases. The most common distant metastatic lesions are caused by breast cancer. In one study, the lumbosacral plexus was involved in 50 of 2261 cases of cervical cancer; however, it was involved in 38 of the 74 patients (51%) in the subgroup with proven retroperitoneal metastatic disease.

The lower (sacral) plexus is involved most frequently (approximately 50%), followed by upper plexus involvement (more than 30%) and panplexopathy (18%).¹ Bilateral plexopathy occurs in 25% of cases and is usually caused by breast cancer metastases. Lower plexus involvement occurs generally with colorectal and cervical neoplasms. Involvement of the sacral sympathetic nerves is less common (10%).

Malignant psoas syndrome (MPS) was first described in 1990 by Stevens and refers to severe and difficult pain due to proximal lumbosacral plexopathy, painful fixed flexion of the ipsilateral hip, and radiologic or pathologic evidence of malignant involvement of the ipsilateral psoas major muscle.²

Frequency

United States

The incidence of neoplastic lumbosacral plexopathy is 0.71%.

Mortality/Morbidity

Significant morbidity from neoplastic lumbosacral plexopathy occurs due to associated pain, weakness, and sensory deficits.³ One study noted median survival of 5.5 months after diagnosis. In patients with prostate cancer,⁴ symptoms may persist for years and survival may be longer.

Race

No known correlation is recognized between the incidence of neoplastic lumbosacral plexopathy and race.

Sex

One study noted a male-to-female ratio for neoplastic lumbosacral plexopathy of 1.3:1, although the investigation involved just a small number of patients.

Age

In one study, age at the time of presentation of neoplastic lumbosacral plexopathy ranged from 19-80 years, with a median age of 65.5 years.

Clinical

History

• Patients with neoplastic lumbosacral plexopathy (NLP) present most frequently (93%) with pain located in regional areas, such as the low back, buttock, hip, and thigh. Features of this pain include the following:
  • The pain may be of unilateral onset, being confined to one side, in 90% of cases.
  • The pain is usually constant, dull, aching, or pressurelike, but it is rarely burning. Cramping may be present in a radicular pattern.
  • The pain may worsen at night, and patients generally have difficulty finding a comfortable position.
  • Involvement of the iliopsoas muscle leads patients to rest with their legs and hips in flexion.
  • Pain exacerbation may occur with prolonged ambulation or sitting.
  • The pain may also radiate down the leg as a result of epidural involvement from the tumor.
  • Eventually, such pain manifests in all patients with NLP and is the most prominent symptom. An absence of pain should prompt consideration of other diagnoses.
  • The presence of autonomic symptoms is less frequent; one of these, the "hot and dry foot," occurs because of the involvement of the sympathetic components of the plexus.⁵ A clear difference in temperature of the affected limb may be reported.
  • When the disease process manifests first with pain, it lasts from 1 week to 13 months, with a median duration of 3 months, before other neurologic symptoms appear.
• Weakness and sensory loss complaints eventually develop in most patients.³ Sensory loss occurs in 50-75% of patients and is more severe with greater motor impairment, potentially adding significantly to the degree of disability for the patient.
• Muscle weakness occurs in most patients and is progressive and diffuse. Unilateral weakness and gait abnormalities are common.
• Incontinence and impotence generally imply bilateral plexus involvement; they occur in about 10% of NLP patients.

Physical

• The most common clinical findings in neoplastic lumbosacral plexopathy include muscle weakness (86%), sensory loss (73%), reflex impairment (64%), and leg edema (47%).
• Diffuse, asymmetrical motor deficits involving more than 1 nerve root develop; associated gait abnormalities are noted.
• With lumbar plexus involvement, weakness usually occurs in the thigh muscles, producing weakness when the patient rises from a seated position or negotiates steps.
• Involvement of the lumbosacral trunk is associated with a foot drop and numbness of the dorsum of the foot.
• In patients with sacral involvement, weakness of foot flexion and hamstrings occurs.
• Sensory deficits are almost exclusively unilateral and can range from mild to severe. The location of sensory deficits in specific dermatomes offers clues to the nerve root or specific nerve involvement.
• Patellar tendon reflex may be impaired with upper plexopathy, and ankle reflex impairment may be noted with lower plexopathy.
• Peripheral edema is seen more commonly with panplexopathy (80%) than with upper (41%) or lower plexopathy (37%).
• Rectal mass is found more often with lower plexopathy (43%) than with upper plexopathy (25%) or panplexopathy (15%).
• A positive straight leg raise test is most common with panplexopathy (83%).
• Pain exacerbation may occur with the Valsalva maneuver.

Causes

Tumor invasion, either local or metastatic, can lead to lumbosacral plexopathy.

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