Abstract ID: A25
Abstract Title: anesthetic management of a patient with a Stiff Person Syndrome
Poster Type: Either
ABSTRACT BODY
Background: Stiff-person syndrome is a rare progressive neurological disorder characterized by constant painful contractions and spasms of voluntary muscles, particularly the muscles of the back and upper legs, resulting in an unsteady gait. Symptoms may occur gradually, spreading from the back and legs to involve the arms and neck.
Stiff-person syndrome is an autoimmune disorder that may be associated with diabetes, pernicious anemia, and thyroiditis (1). We describe the successful anesthetic management of a patient with stiff person syndrome undergoing a right inguinal hernia repair, utilizing a somatic paravertebral block supplemented with conscious sedation.
Case report:
A 65 years old male was scheduled for elective repair of a large right indirect inguinal hernia. His past medical history included diabetes mellitus, hypertension, depression, and stiff person syndrome. His laboratory workup revealed the presence of antibodies to glutamic acid decarboxylase enzyme (GAD) and elevated levels of IgA and thyroglobulin antibodies. An electromyogram (EMG) showed failure of relaxation of the proximal muscle group of both lower extremities and the right upper extremity and suggested a possible central disorder of the motor unit. In addition to a baclofen intrathecal pump, the patient was receiving intravenous immunoglobulins (IVIG) every 2 weeks.
After discussing the risks and benefits of the different anesthetic techniques, a right somatic paravertebral block at T12 and L1 was performed in the sitting position using 5ml of 0.5% bupivacaine at each spinal level. The sitting position was used due to difficulty encountered in positioning the patient in the prone position. Supplemental sedation consisted of intravenous midazolam 1mg, fentanyl 50 ug, and a propofol infusion at 25-35 mcg/kg/min titrated to a Ramsey score of II-III. The patient reported improvement of his spasticity symptoms during the procedure and for one hour into the postoperative period. In the PACU, the patient complained of severe nausea. His vital signs remained stable and his nausea was treated with 8 mg of I.V. ondansetron.
Discussion: Understanding the mechanism of the disease process is crucial in understanding the response of the patient to different induction drugs, inhalational agents, and muscle relaxants. In stiff person syndrome, there is antibody formation against GAD, which is an essential enzyme in the synthesis of GABA. Loss of inhibition from higher centers causes hyperactivity of the peripheral motor unit and subsequent progressive muscle rigidity (1).
The use of regional anesthetic techniques in patients with stiff person syndrome has the advantage of limiting the use of medications necessary during general anesthesia.
In a recent report, it was suggested that the prolonged muscle relaxation seen in these patients is due to enhancement of general anesthetic effect via GABA action on synaptic transmission (2). It was also postulated that the combination of baclofen with volatile anesthetics might lead to postoperative hypotonia and cause prolonged muscle relaxation (3).
The intraoperative improvement in spasticity symptoms in our patient is most probably related to the intravenously administered benzodiazepine and propofol due to their facilitation of inhibitory neurotransmission mediated by GABA. The intraoperative generalized improvement in spasticity symptoms in both the upper and lower extremities suggests a central mechanism versus a localized effect as a result of the somatic paravertebral block.
Reference:
1- Layzer RB. Stiff man Syndrome: an autoimune disease? N Eng J Med.1988; 318:1060-3.
2- Sugimura M, Kitayama S, et al. Effects of GABAergic agents on anesthesia induced by halothane, isoflurane and thiamylal in mice. Pharmacol Biochem Behav 2002; 72:111-6
3- Bouw J, Leenderts K, et al. Stiff person syndrome and Anesthesia: Case report. Anesthesia Analgesia 2003; 97: 486-7.
ATTACHED FILES
Reg Anesth Pain Med 2004; 29(2):A25