eMedicine Specialties > Physical Medicine and Rehabilitation > Plexopathy
Radiation-Induced Lumbosacral Plexopathy: Treatment & Medication
Updated: Oct 17, 2008
- Overview
- Differential Diagnoses & Workup
- Treatment & Medication
- Follow-up
Treatment
Rehabilitation Program
Physical Therapy
Strengthening of lower extremity muscles, use of assistive devices for ambulation (eg, cane, walker), and gait training should be prescribed for patients with weakness and proprioceptive feedback loss. Use of orthotics also may be beneficial in certain individuals with lumbosacral plexopathy.
Occupational Therapy
The patient's ability to perform activities of daily living (ADL) should be assessed, and appropriate assistive device(s) should be prescribed as needed. In particular, safety with standing transfers may be impaired with more distal involvement. With more proximal involvement, sit-to-stand transfers also may be affected. Strengthening exercises, along with sensory reeducation techniques, may be employed.
Medical Issues/Complications
Treatment of postradiation plexopathy is symptomatic. For issues of pain, consider the use of nonopiate pharmacologic medications, such as tricyclic antidepressants or antiepileptic agents (eg, gabapentin, carbamazepine). The use of steroids and opiates, including methadone, can also be considered.
Other Treatment
Nonpharmacologic measures, such as transcutaneous electrical nerve stimulation (TENS), may be used for pain.
While not studied in patients with radiation-induced lumbosacral plexopathy, hyperbaric oxygen therapy has not led to the slowing or reversal of radiation-induced brachial plexopathy symptoms, although improvement was noted in warm sensory threshold.13
In a small population, partial recovery of motor function was noted in few patients treated with anticoagulant therapy for a period of 3-6 months.
Medication
Tricyclic antidepressants (TCAs), such as amitriptyline, may be used in lower doses. The use of antiepileptics may be helpful.
Tricyclic antidepressants
TCAs have central and peripheral anticholinergic effects, as well as sedative effects, and block the active reuptake of norepinephrine and serotonin. The multifactorial mechanism of analgesia may include improved sleep, an altered perception of pain, and an increase in pain threshold. The efficacy of these drugs can be potentiated with the concomitant use of opiates and nonsteroidal anti-inflammatory drugs (NSAIDs). Rarely should these drugs be used in the treatment of acute pain, since a few weeks may be required for them to become effective.
Amitriptyline (Elavil)
Analgesic for certain chronic and neuropathic pain. Amitriptyline has the most anticholinergic side effects of all drugs in this category.
Adult
10-100 mg PO qhs
Pediatric
Not established
Phenobarbital may decrease effects; coadministration with CYP2D6 enzyme system inhibitors (eg, cimetidine, quinidine) may increase levels; inhibits hypotensive effects of guanethidine; may interact with thyroid medications, alcohol, CNS depressants, barbiturates, and disulfiram
Documented hypersensitivity; use of MAOIs in past 14 d; history of seizures, cardiac arrhythmias, glaucoma, and urinary retention
Pregnancy
D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus
Precautions
Caution in cardiac conduction disturbances and history of hyperthyroidism, and renal or hepatic impairment; avoid use in elderly patients
Antiepileptic drugs
These drugs stabilize neuronal membranes and reduce neuronal hyperexcitability. The analgesic effect may be due to such stabilization and control of hyperexcitability, because aberrant electrical activity has been recorded with neuropathic pain.
Gabapentin (Neurontin)
Has anticonvulsant properties and antineuralgic effects; however, the exact mechanism of action is unknown. Gabapentin is structurally related to GABA but does not interact with GABA receptors.
Adult
300-3600 mg/d PO divided tid/qid
Pediatric
Not established
Antacids may significantly reduce bioavailability of gabapentin (administer at least 2 h following antacids); may significantly increase norethindrone levels
Documented hypersensitivity
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Caution in severe renal disease
Carbamazepine (Tegretol)
Used typically for generalized tonic-clonic seizures and partial seizures, as well as for trigeminal neuralgia. Plasma levels are between 4-12 mcg/mL for analgesic and antiseizure response.
Adult
100-200 mg PO bid initial dose; titrate up by 100-200 mg q3-7d; usual dosage for pain control is 400-800 mg/d; increase to tid/qid with larger dose; not to exceed 1200 mg; in rare instances, up to 1600 mg/d
Pediatric
Not established
Serum levels may increase significantly within 30 days of danazol coadministration (avoid whenever possible); do not coadminister with MAOIs; cimetidine may increase toxicity, especially if taken in first 4 wk of therapy; carbamazepine may decrease primidone and phenobarbital levels (their coadministration may increase carbamazepine levels)
Documented hypersensitivity; history of bone marrow depression; administration of MAOIs within last 14 d
Pregnancy
D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus
Precautions
Serious reactions include leukopenia and agranulocytosis; risk is 5-8 times higher than in control population; overall risk per 1,000,000 population per year is 2 patients for aplastic anemia and 6 patients for agranulocytosis; prior to treatment, obtain CBC counts and differentials, along with LFTs; repeat blood count in 2-3 wk and then monthly for 3 mo; if no evidence of bone marrow suppression, then biannual counts should follow; WBC counts below 4000 are contraindication to treatment; discontinue if WBC falls <3000 after treatment, significant thrombocytopenia, abnormality in other blood elements, or significant abnormality in LFTs; other rare drug adverse effects include cardiovascular effects, such as congestive heart failure, arrhythmias, and orthostatic hypotension; hepatotoxicity; inappropriate secretion of antidiuretic hormone (IASDH); severe dermatologic reactions, including Stevens-Johnson syndrome (extremely rare); caution with other TCAs
Valproic acid (Depakene)
Generally indicated for absence seizures and generalized tonic-clonic seizures. Some relief may be noted with neuropathic pain, especially the lancinating type.
Adult
15 mg/kg/d PO initial dose in 2 or more divided doses; titrate by 5-10 mg/kg/d until pain relief is achieved or adverse effects occur; pain relief at levels less than required for antiepileptic activity (50-150 mcg/mL)
Pediatric
Not established
Coadministration with cimetidine, salicylates, felbamate, and erythromycin may increase toxicity; rifampin may significantly reduce valproate levels; in pediatric patients, protein binding and metabolism of valproate decrease when taken concomitantly with salicylates; coadministration with carbamazepine may result in variable changes of carbamazepine concentrations with possible loss of seizure control; valproate may increase diazepam and ethosuximide toxicity (monitor closely); valproate may increase phenobarbital and phenytoin levels while either one may decrease valproate levels; valproate may displace warfarin from protein binding sites (monitor coagulation tests); may increase zidovudine levels in HIV-seropositive patients
Documented hypersensitivity; hepatic disease/dysfunction
Pregnancy
D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus
Precautions
Idiosyncratic reactions include hepatotoxicity (fatalities have been reported), dermatitis, alopecia, encephalopathy, and rare hyperammonemia syndrome; obtain baseline LFTs followed at frequent intervals for first 6 months; monitor serum ammonia, since it can be elevated without corresponding elevation in LFTs
Corticosteroids
Glucocorticoids have anti-inflammatory, hormonal, and metabolic effects. Inflammation is suppressed with the blockage of phospholipase A2, which inhibits the formation of arachidonic acid and, thus, the prostaglandins. The analgesic effect may be due to the anti-inflammatory activity, with a decrease in edema.
Dexamethasone (Decadron, AK-Dex)
For various allergic and inflammatory diseases. Dexamethasone decreases inflammation by suppressing the migration of polymorphonuclear leukocytes and by reducing capillary permeability.
Adult
4-16 mg/d PO
Pediatric
Not established
Decreased blood levels with phenytoin, phenobarbital, ephedrine, and rifampin; watch for development of hypokalemia with administration of potassium-depleting diuretics
Documented hypersensitivity; systemic infections, especially fungal
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Caution in DM, hypertension, renal impairment, osteoporosis, peptic ulcer disease, ocular herpes simplex, cirrhosis, hypothyroidism, and psychotic tendencies; concurrent use of NSAIDs not recommended due to GI toxicity; adverse effects can include hyperglycemia, hypertension, fluid retention, myopathy, osteoporosis, nausea, cataracts, glaucoma, peptic ulcers, convulsions, behavioral disturbances, increased susceptibility to infections, thromboembolism, change in leukocyte/lymphocyte count, malaise, impaired wound healing, increased appetite, and dermatologic effects
Analgesics
These drugs are generally used for short-term, acute pain that is moderate to severe in nature, as well as for chronic pain (eg, cancer). They provide analgesia without antipyretic or anti-inflammatory action. The mechanism of action is the inhibition of nociceptive impulses at the dorsal horn of the spinal cord and at supraspinal sites due to interaction with opiate receptors. Structural derivatives of GABA are also used in the management of neuropathic pain.
Pregabalin (Lyrica)
Structural derivative of GABA. Pregabalin's mechanism of action is unknown. This agent binds with high affinity to the alpha2 -delta site (a calcium channel subunit). In vitro, pregabalin reduces the calcium-dependent release of several neurotransmitters, possibly by modulating calcium channel function. It is FDA approved for neuropathic pain associated with diabetic peripheral neuropathy or postherpetic neuralgia and as an adjunctive therapy in partial-onset seizures.
Adult
50 mg PO tid initially; if needed, may increase to 100 mg tid within 1 wk
Pediatric
Not established
May cause additive effects on cognitive and gross motor functioning when coadministered with drugs that cause dizziness or somnolence
Documented hypersensitivity
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Discontinue gradually (over a minimum of 1 wk) to minimize increased seizure frequency in patients with seizure disorders; may cause insomnia, nausea, headache, or diarrhea with abrupt withdrawal; common adverse effects include dizziness, somnolence, blurred vision, weight gain, and peripheral edema; may elevate creatinine kinase level, decrease platelet count, and increase PR interval; doses >300 mg/d associated with higher rate of adverse effects and treatment discontinuation; decrease dose with renal impairment (ie, CrCl <60 mL/min)
Methadone (Dolophine)
Used in the management of severe pain. Methadone inhibits ascending pain pathways, diminishing the perception of and response to pain.
Adult
2.5-10 mg PO/IM/SC q3-8h prn; increase to a maintenance dose of 5-20 mg q6-8h
Pediatric
Not established
Phenytoin, rifampin, and pentazocine may decrease blood levels of methadone; phenothiazines, tricyclic antidepressants, MAOIs, and CNS depressants may increase the toxicity of methadone
Documented hypersensitivity; bronchial asthma or increased intracranial pressure
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Caution in severe liver disease; due to its relatively long half-life, titrate dose slowly
Morphine sulfate (Duramorph, MS Contin, Astramorph)
Available in immediate (3-4 h duration) and extended release preparation (12 h). Switch over to long-acting preparations (MS Contin) once pain is controlled with short-acting preparation (MS IR). Morphine can produce drug dependence and has the potential for being abused. Tolerance may develop with repeated exposure. Abrupt cessation or sudden reduction in dose with prolonged use may result in withdrawal symptoms. Physical dependence is not of paramount importance in terminally ill patients.
Adult
30 mg PO q3-4h initial dose in opiate-naive patients (no exposure to opiates) or with limited opiate exposure; may be titrated upward by 50% if pain control is inadequate after first 24 h; balance between analgesia and adverse effects
Pediatric
0.3 mg/kg PO q3-4h initial dose
Phenothiazines may antagonize analgesic effects of opiate agonists; TCAs, MAOIs, and other CNS depressants may potentiate adverse effects of morphine
Documented hypersensitivity; hypotension; potentially compromised airway where establishing rapid airway control would be difficult
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Elderly patients; hepatic or renal dysfunction; respiratory disease, obstructive and restrictive (eg, COPD, asthma, kyphoscoliosis); patients with severe obesity or cor pulmonale; head injury and increased intracranial pressure; history of drug abuse; circulatory shock; adverse effect profile includes nausea/vomiting, constipation, sedation, respiratory depression (which occurs more so with opiate-naive patients and with significant pulmonary disease), cardiovascular abnormalities (eg, bradycardia, hypotension), and urinary retention
More on Radiation-Induced Lumbosacral Plexopathy |
| Overview: Radiation-Induced Lumbosacral Plexopathy |
| Differential Diagnoses & Workup: Radiation-Induced Lumbosacral Plexopathy |
 Treatment & Medication: Radiation-Induced Lumbosacral Plexopathy |
| Follow-up: Radiation-Induced Lumbosacral Plexopathy |
| References |
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References
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Further Reading
Keywords
radiation-induced lumbosacral plexopathy, radiation induced lumbosacral plexopathy, plexopathy, plexus, lumbosacral, lumbar sacral, lumbosacral plexus, spine lumbosacral, radiation therapy, radiation plexopathy, motor deficits, limb weakness
