Print version ISSN 0034-7094
Rev. Bras. Anestesiol. vol.54 no.1 Campinas Jan./Feb. 2004
Gabapentin to treat sacral perineural cyst-induced pain. Case report*
Gabapentina en el tratamiento del dolor decurrente de quistes perineurales sacrales. Relato de caso
Elza Magalhães, M.D.I; Ana Márcia Mascarenhas, M.D.II; Durval Campos Kraychete, TSA, M.D.III; Rioko Kimiko Sakata, TSA, M.D.IV
IPós-Graduanda de Neurociências
IIAnestesiologista/Intensivista e Estagiária do Ambulatório de Dor do HUPES-UFBA
IIICoordenador do Ambulatório de Dor do HUPES-UFBA e Coordenador do Curso de Pós Graduação em Dor da UNIFACS-BA
IVCoordenadora do Ambulatório de Dor da Universidade Federal de São Paulo
BACKGROUND AND OBJECTIVES: Perineural
cysts may induce difficult to control neuropathic pain. Anticonvulsivants are
used to treat such pain. This report aimed at presenting a case of total pain
remission with gabapentin after failure of all other therapeutic alternatives
CASE REPORT: Female, diabetic patient, 67 years old, complaining of lumbosacral pain for two months, with the following characteristics: daily, sharp and burning pain of mild to moderate intensity irradiating to posterior thigh. Pain would worsen with movement and in the standing position. Six months before she had had a similar pain episode which improved with steroids. Lumbosacral spine MRI showed 2.5 cm sacral perineural cyst injuries at S1, S2 and S3, compressing the dural sac and associated to bone erosion. Gabapentin was introduced in progressive doses until 900 mg/day, with complete pain relief.
CONCLUSIONS: Tarlov's cyst neuropathic pain may be adequately controlled with gabapentin.
Key Words: DISEASE, Neurologic: perineural cysts; DRUGS: gabapentin; PAIN, Chronic
JUSTIFICATIVA Y OBJETIVOS: Los quistes
perineurales pueden generar dolor con características neuropáticas
de difícil control. Los anticonvulsivantes son medicaciones utilizadas
para tratamiento de dolores con esas características. El objetivo de
este relato es mostrar un caso con total remisión del dolor con el uso
de gabapentina después del mal suceso en el tratamiento con todas las
otras alternativas terapéuticas utilizadas.
RELATO DE CASO: Paciente de 67 anos, diabética, con queja de dolor lombosacra hace dos meses, con las siguientes características: diaria, en puntada y quemazón, de intensidad leve a moderada y con irradiación para región posterior del muslo. Peoraba con el movimiento y con la posición ortostática. Hace seis meses tuvo un episodio semejante de dolor, que mejoró con el uso de corticoesteróides. La resonancia nuclear magnética de la columna lombosacra mostraba lesiones císticas perineurales sacrales en S1, S2 y S3 con diámetro de 2,5 a 4 cm, comprimiendo el saco dural asociado a la erosión ósea. Fue introducida la gabapentina en dosis progresivas hasta 900 mg/día, con alivio completo del cuadro álgico.
CONCLUSIONES: El dolor neuropático provocado por el quiste de Tarlov puede ser controlada de manera adecuada con gabapentina.
Lumbosacral cysts are classified based on their location, content and association with neural tube malformations. Most common malformations are meningocele and meningomyelocele. Spinal cysts were classified in 1988 in three major categories: type I - extradural cyst without nervous root fibers, which may be subdivided in type IA (extradural meningeal cyst) and IB (sacral meningocele); type II - extradural spinal meningeal cyst with nervous root fibers; and type III - intradural spinal cyst 1. Our case was a type II or Tarlovs cyst.
Direct nervous roots involvement by cyst walls and consequent injuries to axons centrally carrying painful information, lead to spontaneous afferent nerves discharge due to mechanical stimulation and changes in medullary and central nociceptive pathways physiology, inducing pain with neuropathic characteristics. Gabapentin inhibits aspartate and glutamate action, thus decreasing ascending nociceptive impulses and relieving pain. In addition, it increases GABA and serotonin concentration in the central nervous system due to a further local glutamate decrease, and blocks neuronal Na+ and Ca++ channels, further contributing to analgesia.
This report aimed at presenting a case of chronic pain in patient with perineural cyst (Tarlovs disease), successfully treated with gabapentin.
Female, diabetic patient, (controlled with metformin - 500 mg/day), 67 years old, referred to Hospital Universitário Professor Edgard Santos - UFBAs pain service, complaining of lumbosacral pain for two months, with the following characteristics: daily, sharp and burning pain of mild to moderate intensity irradiating to posterior thigh. Pain would worsen with movement and in the standing position. Six months before she had had a similar pain episode which improved with steroids. For this pain episode she had already used opioids, anti-inflammatory drugs, steroids, acupuncture, physical therapy and pilates, without improvement. At physical evaluation she presented triggering points at lumbar region and breeches. Lumbosacral spine MRI showed 2.5 to 4 cm sacral perineural cystic lesions at S1, S2 and S3 compressing the dural sac and associated to bone erosion (Figures 1 and 2). Gabapentin was introduced in progressive doses until 900 mg/day with complete pain relief.
Fetal dural sac and neural tube extend along the sacral nerve to the terminal filament. Then, neural tube loses this connection with the terminal filament with cranial retraction, thus decreasing the dural sac, which remains so until adulthood. If dural sac ascension is delayed, it may acquire the appearance of sacral cysts and remain like that. Theories for the pathogenesis of sacral cysts are still under discussion. Cysts might be a consequence of migration defects and slow development of the neural tube after mesoderm differentiation, dural rupture by direct trauma, changes in neural tube closing and failure in meningeal sac ascension 2,3. It was impossible, in our case, to define which theory would have explained the ethiology.
Although many sacral cysts are asymptomatic, some may have symptoms. There might be radicular and perineal pain associated to paresthesias, due to compression or stretching of roots involved by the cysts 4. Low intermittent lumbar pain is present in 80% of patients and may be worsened by physical activity or Valsalva maneuver. There might be sphincter dysfunctions, such as dysuria, retention, incontinence, constipation. Erectile dysfunction is an occasional finding 3,5,6. Surgical treatment is indicated when there is neurological abnormality 2,4.
Differential sacral cysts diagnosis includes tumors, abscesses and extradural hematomas 3. Diagnosis is confirmed by radiological exams, such as myelography or computerized tomography (CT), but magnetic resonance image (MRI) is the exam of choice for the possibility of more precisely differentiating tissue density and the absence of bone interferences. MRI is a non-invasive test able to evidence canal or sacral foramens bone erosions 2,3,7.
Tarlovs cyst may induce lumbar sciatic pain and should be considered differential diagnosis for other diseases causing radicular symptoms at this level. Due to nervous structures compression, Tarlovs cyst-induced pain has neuropathic characteristics.
Neuropathic pain is associated to the following mechanisms 8-10: changes in inhibitory and excitatory neurotransmitters quantity; changes in central nervous system synapses; inhibitory synapses become excitatory, latent synapses are activated, and thick fibers may synapse with thin fibers; decrease in pain descending inhibitory mechanisms; changes in sympathetic system, among others.
Pain should be treated with adequate drugs. Conservative treatment is basically pain relief and physical therapy to stabilize abdominal and pelvic muscles 6. Surgical treatment involves laminectomy with cyst wall drainage and cauterization 11, but this procedure may promote neurological changes. Another surgical alternative is percutaneous drainage, which might have to be repeated due to cysts recurrence 11. Risks include infection and headache 6. Our patient had complete remission with gabapentin.
Approved by the FDA in 1993, gabapentin has a complex and multiple action mechanism. It promotes increased GABA effect on central nervous system, decreased glutamate and the blockade of neuronal sodium and calcium channels 10,12,13.
Gabapentin is absorbed by the small intestine with dose-dependent bioavailability, which is linear with low doses (up to 1800 mg) and non-linear with high doses (> 3600 mg), with consequent variations in serum concentrations 14.
To date, no significant blood, liver and skin complications have been reported. Its adverse effects are directly related to the dose and the most common are sleepiness, present in 20% of patients; ataxia in 17%; nystagmus in 15%; and asthenia.
Gabapentin is considered a safe anticonvulsivant drug among those available in the market 13.
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Dra. Elza Magalhães
Address: Rua Genésio Sales 89/301 Vila Laura
ZIP: 40270-130 City: Salvador, Brazil
Submitted for publication February 24, 2003
Accepted for publication June 3, 2003
* Received from Ambulatório de Dor do Hospital Universitário Prof. Edgard Santos (HUPES) UFBA, Pós-Graduação em Dor, UNIFACS, BA