Introduction: Stiff Person Syndrome is characterized as a neurological disease causing fluctuating muscle rigidity escalating to painful spasms. The presence of antibodies against glutamic acid decarboxylase, an enzyme in the pathway of the inhibitory neurotransmitter gamma-aminobutyric acid is the proposed cause. Central muscle groups are affected first but the disease can progress to include distal muscle groups yielding limited use of limbs.
Case report: A 55 year old male, with diagnosed stiff person syndrome, presented for ambulatory surgery. Obesity and parathyroid disease defined past medical history. All pre-operative laboratory testing fell within normal limits. Midazolam 2mg IV pretreatment preceded transfer to the operating room. Midazolam 2mg IV and intermittent doses of Ketamine totaling 60 mg IV over a 15 minute period maintained monitored anesthesia care. The patient remained comfortable and calm through the procedure and was transferred to the post-anesthesia care unit on nasal cannula oxygen for observation. No exacerbation of symptoms ensued.
Discussion: Many anesthetic agents are associated with enhancement of GABA-ergic inhibition making the care of a patient with stiff person syndrome challenging. Existing case reports are inconclusive in describing prolonged hypotonia following general anesthesia using inhalation gases and muscle relaxants. High stress can exacerbate an event. A previous case report showed that propofol could be used safely for a short procedure and may have the benefit of improved sequelae of stiff person syndrome following the procedure. However, because of the patients' airway ketamine was chosen. Patient comfort without residual effects of stiff person syndrome was achieved.
Keywords: Stiff person syndrome, ketamine, ambulatory surgery, ilioinguinal nerve block