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Sunday, July 10, 2011

Stiff Person Syndrome

Stiff Person Syndrome and Anesthesia: Case Report

  1. Jans Bouw, MD*
  2. Karin Leendertse, MD*
  3. Marina A. J. Tijssen, MD PhDand 
  4. Misa Dzoljic, MD PhD*
+Author Affiliations
  1. *Departments of Anesthesiology and †Neurology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
  1. Address correspondence and reprint requests to J. Bouw, MD, Department of Anesthesiology, Academic Medical Center, University of Amsterdam, PO Box 22700, 1100 DE Amsterdam, The Netherlands. Address e-mail toj.bouw@amc.uva.nl.

Abstract

IMPLICATIONS: This case report describes the successful perioperative management of a patient with a rare and disabling neurologic disorder, the stiff person syndrome. The patient had a delayed emergence despite apparent full reversal of neuromuscular blockade. We suggest an interaction between the GABAergic effects of baclofen and volatile anesthetics as a possible cause.
Stiff person syndrome (SPS) is a rare and disabling neurologic disorder characterized by muscle rigidity and episodic spasms that involve axial and limb musculature (1–3). The literature points toward an autoimmune disorder resulting in a malfunction of γ-aminobutyric acid (GABA)-mediated inhibitory networks in the central nervous system (4). Anesthetic implications are less well described. We report a case of prolonged hypotonicity after general anesthesia in a patient with SPS and discuss the possible anesthetic interactions.

Case Report

A 62-yr-old woman (height, 1.70 m; weight, 61 kg) was scheduled for resection of a colon carcinoma. Her medical history revealed hypothyroidism, vitamin B12 deficiency, and SPS. This syndrome started with low back pain, which rendered her unable to walk. She was experiencing stiffness, involuntary jerks, and painful cramps. Neurological examination revealed extreme hypertonia of the body and proximal legs, with intercurrent, painful spasms. Reflexes were symmetrical without Babinski signs. Laboratory findings showed positive glutamic acid decarboxylase (GAD) and negative amphiphysin antibodies. The patient was successfully treated with baclofen and diazepam. Subsequently, prednisone as immunosuppressive therapy was started. The stiffness diminished, and the patient was able to walk unaided. The neurological examination was unremarkable, except for a slight stiffness in the legs. Her medication at admission was prednisone 20 mg once a day, baclophen 12.5 mg twice a day (daily dose = 25 mg), diazepam 7.5 mg twice a day (daily dose = 15 mg), levothyroxine 25 μg once a day, and vitamin B12 injections. Her medical history included urological and gynecological surgery under general anesthesia before she experienced SPS.
No premedication was given. Anesthesia was induced with propofol (2.5 mg/kg) and sufentanil (0.25 μg/kg). After the administration of atracurium (0.6 mg/kg), the trachea was intubated, and anesthesia was continued with isoflurane (0.6–1.0 vol%) and oxygen/air for the duration of the procedure. Cefuroxime 1500 mg, clindamycin 600 mg, and dexamethasone 10 mg were administered IV. In the following 2 h, additional atracurium (35 mg), sufentanil (10 μg), and morphine (8 mg) were administered. At the end of the procedure, which was uneventful, neuromuscular monitoring showed four strong twitches. Although the patient was responsive, she could not open her eyes, grasp with either hand, or generate tidal volumes beyond 200 mL. Neostigmine 2 mg (0.03 mg/kg) and glycopyrrolate 0.2 mg did not alter the clinical signs of muscle weakness.
The patient was sedated with propofol 5 mg · kg−1 · h−1 and further mechanically ventilated in the recovery room. After 1 h, the sedation was stopped and mechanical ventilation was terminated. At that time, baclofen 12.5 mg was administered into the gastric tube. Two hours later she was in a good clinical condition, and her trachea was extubated.

Discussion

SPS was recognized as a distinct entity in 1956 by Moersch and Woltman (5). An autoimmune pathogenesis is suspected because of the presence of antibodies against GAD, the rate-limiting enzyme for synthesis of the inhibitory neurotransmitter GABA, and the association of the disease with other autoimmune conditions such as diabetes and thyroiditis (6,7). Loss of inhibition from higher centers causes hyperactivity of the γ-motor neuron system and subsequent progressive muscle rigidity. Patients with SPS have high immunoglobulin G/anti-GAD-65 antibodies, which are synthesized intrathecally and seem to impair the in situ synthesis of GABA (8,9). Two types of drugs have been applied: drugs that enhance GABA activity and immunosuppressing drugs. Diazepam, which increases the frequency of opening of the GABAA receptor and leads to hyperpolarization, is the initial treatment of choice at daily doses up to 200 mg. Intrathecal or oral baclofen may improve the physical symptoms just like prednisone, plasmapheresis, and large-dose IV immunoglobulin (10).
In our case, several drugs could have caused muscle weakness (11). Initially atracurium could be suspected. Computer-simulated pharmacokinetic analyses suggested that plasma concentrations were far less than therapeutic levels. The same can be said for opioids, fentanyl, and morphine (Fig. 1(12–15). In the recovery room while the patient was still ventilated, it showed a diazepam serum concentration of 0.317 mg/L (therapeutic range, 0.125–0.75 mg/L). Because IV drugs can be excluded as causing muscular weakness, perhaps volatile anesthetics were the cause. In the case report by Johnson and Miller (10), muscle weakness was observed only when baclofen was combined with inhaled desflurane or isoflurane. Delayed arousal and muscle weakness were also described, unrelated to SPS, in a patient receiving baclofen and undergoing anesthesia with isoflurane 1% (16). In addition, recent animal studies show that baclofen enhances volatile anesthetic-induced anesthesia (17). Perhaps the complicated course of recovery was most due to the interaction between isoflurane and baclofen causing muscle weakness.
Figure 1. Chart showing three different drugs given during the procedure. Time 0 represents the start of the procedure, which ended after 150 min. The serum concentrations of sufentanil and atracurium, although given in different units, can be seen on the left axis, and the right axis represents serum concentrations of morphine. It is noteworthy that after the initial intubation dose of atracurium, three doses (5, 10, and 20 mg) were given during the procedure.
We thus conclude that the prolonged muscle relaxation can be explained by the enhancement of general anesthetics via GABAB action on synaptic transmission (17). This case demonstrates a potential danger in combining baclofen with volatile anesthetics in patients with SPS.

Saturday, July 2, 2011

ANAESTHESIA FOR DAY SURGERY


THE HONG KONG COLLEGE OF ANAESTHESIOLOGISTS P5 February 1993
Reviewed Feb 2002
GUIDELINES FOR DAY CASE SURGERY
GUIDELINES ON ANAESTHESIA FOR DAY SURGERY
1. GENERAL COMMENTS
Safety of anaesthesia must not be compromised by financial or other expediency,
to the detriment of those who, by definition, are fitter than the majority of the
population.
2. FACTORS AFFECTING CHOICE OF PATIENT
2.1 Patients should be ASA (American Society of Anaesthesiologists) grade I or II. Exceptionally ASA grade III may be accepted.
2.2 Children, (who should be over six months of age), must be accompanied by parents/guardians at all relevant times.
2.3 Patients should reside within easy access to the surgical facility.
3. PREANAESTHETIC ASSESSMENT
3.1 Every patient must have a preanaesthetic assessment by an anaesthesiologist, preferably by the one who will administer the anaesthetic.
3.2 This assessment may be made in a hospital, clinic or in the day case centre.
3.3 When appropriate, the results of investigations, eg. chest X-ray, electrocardiogram, serum electrolyte and urea concentrations, and urinalysis, must be available to the assessing anaesthesiologist.
3.4 Acceptance for day case anaesthesia should be refused if the patient is unfit, appropriate medical information is lacking or the likelihood of complications is high.
4. PREANAESTHETIC INSTRUCTIONS
4.1 Proforma should be prepared to advise the patient/guardian of details about fasting time, reporting time and admission procedures.
4.2 In the case of a minor, a parent/guardian must accompany the patient to elaborate, if necessary, on the medical history (vide 3.1), and provide assistance, if required during induction and/or recovery.
4.3 Signed consent for the proposed procedure must be obtained from the patient or guardian and a preoperative leaflet discussed and handed out.
5. STAFFING
5.1 The anaesthesiologist must be provided with a dedicated and appropriately trained assistant.
5.2 There must be adequate assistance for the transporting and positioning of patients.
5.3 A qualified anaesthesiologist should be immediately available when anaesthesia is given by a trainee.

6. FACILITIES
6.1 The day surgery centre must have facilities which conform with the guidelines issued by the College, in particular :-
Recommended minimum facilities for safe anaesthetic practice in operating suites (T2).
Guidelines for monitoring in anaesthesia (P1).
Guidelines for postanaesthetic recovery care (P3).
6.2 Easy access to transport facilities is important.
7. SURGICAL CASE SELECTION
7.1 The scope and nature of surgery must be agreed by the surgeon and anaesthesiologist responsible for the day surgery in the centre.
7.2 Patients who might require blood transfusion, suffer excessive postoperative discomfort, or who are unlikely to be fit to be discharged home on the same day, are unsuitable for day surgery.
7.3 Patients living in single accommodation or who are unable to provide a responsible person to oversee their welfare for the first 24 hours cannot be accepted for day surgery.
8. POSTOPERATIVE RECOVERY
8.1 Patients must be observed and recovered by appropriately trained staff prior to discharge.
8.2 There should be a record of recovery to include conscious state, orientation,
sensory and motor function (including locomotion), pulse rate, blood pressure, and any postoperative pain.
9. DISCHARGE
9.1 Verbal and written instructions must be given to the patient and/or guardian prior to discharge with particular reference to :-
9.1.1 Immediate action in the event of complications, and
9.1.2 Whom to contact (with telephone number).
9.2 The patient must be advised verbally and in writing, that, in the first 24 hours
postoperatively, he/she must NOT :-
9.2.1 Drive or operate machinery.
9.2.2 Cook.
9.2.3 Work or make important decisions.
9.2.4 Drink alcohol.
9.2.5 Take any medication except that approved by the day case centre.
9.3 The patient must be escorted home by a responsible adult by private transport. In
the case of a minor, the responsible person attending the child during transport
should not be the driver.
9.4 If the discharge criteria are not met, the patient must be admitted.
9.5 The anaesthesiologist who gave the anaesthetic, in conjunction with the operator
and the nursing officer in charge of the day case centre, is responsible for the
discharge of the patient in accordance with agreed protocols.
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