Anaesthetic management of a case of idiopathic intracranial hypertension

Bina P Butala and Veena R Shah

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Abstract

Idiopathic intracranial hypertension (IIH) is a rare headache syndrome characterized by prolonged elevation of intracranial pressure without related pathology in either the brain or the composition of cerebrospinal fluid. Herein, we provide a brief review of the clinical presentation of IIH and the anaesthetic considerations in a female posted for transcervical resection of the endometrium and right nephrectomy with the disorder. Most of patients with IIH are reported during pregnancy and came for management of labour and delivery. To our knowledge no such case has been described previously.

Keywords: Cerebrospinal fluid, idiopathic intracranial hypertension, intra cranial pressure, lumbar puncture, papilledema

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INTRODUCTION

Idiopathic intracranial hypertension (IIH) was first described in 1893. Patients with IIH have a classical picture of headache, papilledema, and a raised cerebrospinal fluid (CSF) pressure of more than 25 mmHg. It is more common in women than in men (3:1) with the highest incidence seen in obese women of reproductive age group (20-45 years). The most common presenting symptoms are manifestations of generalized intracranial hypertension, normally headache and visual obscuration. Diplopia, pulsatile tinnitus, nausea and vomiting may be present in about 50% of patients, with neck/back/shoulder pain or radicular pain less frequent.[1] The major risk of IIH is visual loss, which may be permanent despite medical therapy. It seems that the symptoms worsen during pregnancy in 50% of the patients and usually resolve postpartum.[2]

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CASE REPORT

A 45-year-old female, weighing 70 kg presented with complaints of headache, menorrhagia and pain in the abdomen was admitted to our hospital. She was posted for transcervical resection of the endometrium and patient had a past history of headache and blurring of vision 2 years ago and was diagnosed to have IIH and was on tablet acetazolamide 250 mg every 6 h. She had a history of lumbar CSF drainage twice. Patient had a history of hypertension and was on tablet atenolol once daily. On pre-operative examination, pulse was 70/min and blood pressure was under control. Other general and systemic examination was normal. All other investigations were within normal limits. Computer tomography brain was normal and magnetic resonance imaging revealed partially empty sella and no pituitary mass lesion, cerebral hemisphere and ventricles were normal. Fundus examination revealed chronic papilledema, optic nerve pallor and perimetry showed increased size of blind spot. Neurologist advised preoperative CSF pressure measurement and drainage if pressure is high. CSF manometry was performed in the lateral decubitus position and CSF pressure was more than 250 mm H2O with normal cytological and biochemical profile. 20 mL of CSF was drained with a 22 gauge Quincke's needle. After drainage the CSF pressure was 150 mm H2O. Patient was posted for surgery after 2 days.

On the day of surgery, injection glycopyrrolate (0.2 mg), injection midazolam (2 mg) and injection fentanyl (200 μg) were given intravenously as pre-medication. Anaesthesia was induced with propofol 175 mg and tracheal intubation was facilitated with vecuronium 5 mg injection plain lignocaine 2% 5 ml was given to attenuate pressor response. Anaesthesia was maintained with oxygen, nitrous oxide, propofol infusion, and vecuronium. Intra-operatively injection mannitol 1 g/kg was given. Monitoring included pulse oximetry, electrocardiogram (ECG), noninvasive blood pressure noninvasive blood pressure (NIBP), ETCO2, urine out-put and temperature. At the end of surgery neuro-muscular block was reversed with injection neostigmine 3.5 mg and glycopyrrolate 0.4 mg. She was shifted to post-operative recovery room and monitored for 48 h with pulse oximetry, ECG, NIBP, urine out-put, and temperature. She was completely asymptomatic at discharge.

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DISCUSSION

IIH was first described by Quinke in 1893 and was called “serous meningitis.” IIH is caused by dural sinus thrombosis, a reduction in corticosteroid therapy, hormonal imbalance, vitamin A toxicity, anabolic corticosteroids, long-term tetracycline, hormonal contraceptives, lithium, and pregnancy.[3] Theories of IIH pathophysiology include increased venous sinus pressure, decreased spinal fluid absorption, increased spinal fluid secretion, increased blood volume and brain oedema.[4] The various treatment modalities used in patients include corticosteroids, acetazolamide, diuretics, repeated lumbar puncture and surgery. The goals of treatment of IIH involve a reduction of intracranial pressure to control symptoms and prevent pressure on the optic nerve and optic meninges, preserving vision. Serial lumbar punctures have a success rate of 30-40% when used alone. Generally, up to 30 ml of fluid is withdrawn to lower the intracranial pressure to normal.[5] Our patient had a history of IIH since 2 years, was on tablet acetazolamide and showed response to medical therapy. Lumbar puncture was carried out twice to improve symptoms. In our patient, 20 cc of CSF was removed to keep the CSF pressure within normal limits.

From the literature, it has been found that IIH is more common in females in the age group 20-45 years.[5] Women with more than 10% over their ideal body weight are 13 times more likely to develop IIH.[5] Our patient was having a body mass index of >30 kg/m2. The mechanism proposed is that central obesity raises intra-abdominal pressure, which increases intra-pleural pressure and cardiac filling pressure, which in turn impedes venous return from the brain and leads to increased intracranial venous pressure, and increased intracranial pressure.[5]

Neuraxial anaesthesia, spinal or epidural has been used successfully for caesarean section in patients with IIH. Since lumbar puncture for CSF drainage is a therapeutic modality for IIH, there is no indication to withhold spinal anaesthesia in these patients.[5] Bedson and Plaat reported the combined spinal-epidural technique for delivery by caesarean section.[1] Although, dural puncture is contraindicated in patients with increased intracranial pressure resulting from space occupying lesions due to risk of uncal herniation. However, it has been postulated that the uniform swelling and stiffness of the brain in IIH prevents herniation.[5] Aly and Lawther reported a case of uncontrolled IIH successfully managed using an epidural catheter for analgesia in labour and delivery as well as temporary control of intracranial pressure.[1] Abouleish and Ali had given spinal anaesthesia for caesarean section in patient with IIH.[6]

In our patient, both surgeries were carried out simultaneously, so we had no option for regional anaesthesia. We have selected general anaesthesia as nephrectomy was carried out in the lateral decubitus position. If a patient with IIH requires general anaesthesia, the planned approach should minimize the risk of a rise in intracranial pressure associated with intubation, inadequate depth of anaesthesia and extubation. So, we have to take measures to avoid an increase in intracranial pressure (ICP) during the peri-operative period.

Propofol offers a number of pharmacological advantages for total intravenous anaesthesia in patients of raised ICP. It decreases cerebral blood flow and cerebral oxygen consumption and increases cerebrovascular resistance. It could offer cerebral protection.[7] The synthetic short acting opioids like fentanyl lack any significant effect on ICP.

Induction and intubation may aggravate intracranial hypertension. Liberal doses of propofol combined with narcotics to achieve adequate depth of anaesthesia, mild to moderate hyperventilation, intravenous lignocaine bolus are the measures that prevent dangerous increase in ICP. We induced the patient with (200 μg) fentanyl and propofol and avoided succinylcholine for intubation as muscle fasciculation caused by succinylcholine, increase the intra cerebral blood volume and increase the ICP. Intubation in lighter planes of anaesthesia should be avoided. Atracurium causes histamine release, slightly increases the pulse rate and central system excitement, so we have used vecuronium in our patient. Vecuronium does not alter ICP or CSF dynamics and lack of cerebral effects have made vecuronium a popular choice in patients with raised ICP. Definitive measures used for decreasing the ICP include, mild head elevation, maintain EtCO2 between 25 mmHg and 30 mmHg, I.V. mannitol, continuous infusion of thiopentone or propofol, avoid hypoxia, hypercarbia, hyperthermia and hypotension.

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CONCLUSION

In conclusion, although IIH is rare, there are special considerations for anaesthetic management in patients with this disorder. Even though, these patients have an elevated ICP, anaesthesia does not cause any detrimental effects in patients with IIH. So, we have to take measures to avoid increase in ICP during the perioperative period. Despite the presence of raised ICP in these patients, there is no specific contraindication to either spinal or epidural anaesthetic technique since uncal herniation does not occur in these patients. The main goal is to avoid further increases in ICP.

hyperkalemia

Anaesthetic management in a patient with multiple sclerosis

Anaesthetic management in a patient with multiple sclerosis

Lata M Kulkarni, CS Sanikop, HL Shilpa, Anupama Vinayan
Department of Anaesthesiology, KLE University's, Jawaharlal Nehru Medical College & KLES Dr. Prabhakar Kore Hospital, Nehru Nagar, Belgaum, India

Introduction

Multiple sclerosis (MS) is an autoimmune demyelinating disorder of the central nervous system (CNS) with genetic predisposition characterized by a wide variety of neurological impairment and symptoms due to multi-focal areas of inflammation and demyelination in brain and spinal cord. ^[1],[2] The treatment is symptomatic and with immunosuppressant drugs as there is no cure for MS. 

Prevalence, increases with latitude, is rare in Asian countries, highest in north Scotland, northern Europe, and northern United States and in Canada. ^[1] 

Exact prevalence in India is not available, but occasionally an anaesthesiologist may encounter a case of MS. 

Case Report

A boy of sixteen years who was a known case of MS for past eight years presented with fracture shaft of femur following a sudden fall while on treatment of MS following a relapse and was scheduled to undergo open reduction, internal fixation. He had history of limb weakness, relapsing--remitting type with movement-induced muscle spasms, gradually progressing in all the four limbs. During past two months there was diminution of vision in both the eyes and he was restricted to bed. Bowel and bladder function was normal. There was no history of seizures, difficulty in speech, swallowing and breathing. On examination he was moderate in built, weighed 38 kg with normal pulse, blood-pressure, respiration and temperature. 

CNS examination revealed a conscious patient with normal higher functions, but mentally depressed. Speech was normal. There was loss of power in all the four limbs, 2/5 in both upper limbs and 2/5 in right lower limb (left lower limb with fracture) as per Medical Research Council (MRC) rating. Co-ordination was impaired in upper and lower limbs with marked movement-induced spasticity, hyper responsive deep reflexes and up-going Babinski. He also had optic neuritis. Gait could not be tested. His sensory system, other cranial nerves, brain-stem function appeared normal. Heart-rate response to deep breathing was normal. His other systems were normal. 

Laboratory investigations (routine haematological, liver and kidney function, serum electrolytes), chest X-ray and electrocardiogram (ECG) were normal.

Magnetic resonance imaging (MRI) scan showed patchy bright signals within the cord on T ₂ -weighed images from C ₁ to T ₁₀ vertebral levels suggesting demyelination. No focal lesion of brain parenchyma was seen. 

He was receiving oral methotrexate and folic acid, oral baclofen and methylcobalamin for last six years. Recently, he was treated with intravenous (I.V.) methyl prednisolone during an acute attack followed by tapering dose of oral prednisolone, during last 6-8 weeks.

Propofol induced refractory status epilepticus

Study affiliation: Doctor Soliman Fakeeh Hospital, Jeddah Saudi Arabia.
Curr Pediatr Res 2010; 14 (1): 43-45
Successful treatment of Propofol induced refractory status epilepticus with calcium gluconate
Rafat Mosalli
Department of Pediatrics, Omm Al-Qura University, Mecca, Saudi Arabia
Abstract
Propofol-induced seizure-like phenomena (SLP) is well described following anesthesia or sedation with this drug. The episode is usually benign and responds well to standards anti-convulsant therapy. The occurrence of status epilepticus refractory to conventional treat-ment and successful treatment with intravenous Calcium has been rarely reported. We de-scribe a patient who developed status epilepticus refractory to standard treatment during recovery from Propofol anesthesia and successfully treated with intravenous calcium. The report highlights a potentially harmful complication of the Propofol and suggests that intra-venous calcium may be effective as an anticonvulsant treatment for Propofol-induced status epilepticus.
Key words: Propofol, seizure, calcium , status epilepticus.

Neuroleptic Malignant Syndrome

The Indian Anaesthetists’ Forum – (http://www.theiaforum.org)                    Online ISSN 0973-0311
January 2010(4)
Agrawal P,Agrawal A, Singh I: Neuroleptic Malignant Syndrome and Anaesthesia : A Case Report  1
Neuroleptic Malignant Syndrome and Anaesthesia: A Case Report
1. DNB Resident Presently working as Senior Resident, JPNATC, AIIMS, New Delhi
2. Consultant, 3. Head of the Department
Department of Anaesthesiology and Intensive Care
Jaipur Golden Hospital, Rohini, New Delhi.
Correspondence: Pramendra Agrawal (pramendraagrawal@yahoo.com)  
About the Author: Dr Pramendra Agrawal passed
DNB in Anaesthesiology in the year 2008. He is
presently working as Senior Resident in Jai Prakash
Narayan Apex Trauma Centre, All India Institute of
Medical Sciences [AIIMS], New Delhi, India. His field
of interests include trauma care, regional interventional techniques and intensive care.
Neuroleptic Malignant Syndrome (NMS) is a life threatening, neurological disorder most
often caused by an adverse reaction to neuroleptic or anti psychotic drugs. We report a case
of Neuroleptic Malignant Syndrome who was posted for an incidental surgery and its
anaesthetic management.
Key Words: Neuroleptic Malignant Syndrome, anti psychotics, hyperthermia
Neuroleptic Malignant Syndrome (NMS) is a rare but  potentially life threatening
idiosyncratic reaction to neuroleptic drugs. It causes hyperthermia, muscular rigidity, altered
mental status, elevated creatine phosphokinase (CPK) and autonomic dysfunction. The
underlying pathological abnormality is thought to be the central dopamine D2 receptor
blockade or dopamine depletion in the hypothalamus, nigrostriatal and spinal pathways.
The condition shares many features with the serotonin syndrome and malignant
hyperthermia. Anaesthesia for an incidental surgery in such a patient poses unique
challenges to an anaesthesiologist.  
Case Report: An 18 year old male, a known case of Bipolar mood disorder on antipsychotics
was admitted to our Intensive Care Unit with complaints of high grade fever (106F) for 2
days, agitation and involuntary movements for 8 days and vomiting with altered sensorium
for 1 day. Patient was immediately intubated to protect his airway, intensive measures to
bring down temperature commenced and investigations including haematological, biochemical, brain imaging and cerebrospinal fluid sent for evaluation. Investigations revealed:
 elevated liver enzymes (SGOT 477 IU/l, SGPT 190  IU/l);
progressively increasing Creatine Kinase (1004; 2040; 3270; 39794 U/l), Serum Creatinine
(1.3; 1.5; 1.8 mg/dl) and Serum K+ (4.8, 4.9, 5.5 meq/l). Computed tomography of brain and
cerebrospinal fluid examination were normal.  So a  diagnosis of neuroleptic malignant
syndrome was made.  All antipsychotic medications were then stopped.  Tab. Bromocriptine
1.25 mg thrice daily and Tab. Alprazolam 0.25 mg four times daily were started and other
intensive care measures continued. Patient was gradually weaned off ventilator support and
extubated on 6th day.
Unfortunately patient developed a bed sore on the buttock which needed a flap
cover He was posted for surgery on 15th day of admission. A pre-anaesthetic check up
revealed a responsive patient, hypertonia present in all limbs and restricted mouth opening
(just 2 fingers due to hypertonia). Investigations  revealed elevated CPK 829 U/l, S. K+ 4.9
meq/l, INR = 1.54; rest of examination and investigations were within acceptable limits.
Anaesthetic management included avoidance of following drugs perioperatively: Inj.
droperidol, succinylcholine, prochlorperazine, promethazine and metoclopramide. Patient
received premedication with alprazolam 0.25 mg at 10 p.m. before the day of operation and
at 6 a.m. on day of surgery. Consent taken and patient shifted to operation theatre. Drip
started with 16 G intravenous cannula and standard  monitoring established. Fentanyl 1.5
µg/kg and midazolam 1 mg IV was administered. Anaesthesia induced by thiopentone
sodium 4 mg/kg IV slowly, after pre-oxygenation or  5 minutes and adequacy of mask
ventilation confirmed, muscle paralysis achieved with atracurium 0.5mg/kg. Airway secured
with 34Fr cuffed armoured endotracheal tube orally and anaesthesia maintained with 50%
of O2 + N2O + Isoflurane < 0.4%, fentaynl was used for analgesia and atracurium for muscle
paralysis assisted by neuromuscular monitoring. Surgery was conducted in prone position;
procedure lasted 2½   hours during which 2 units of whole blood, 2 units of FFP and 1.5 litres
crystalloid were infused. Patient remained haemodynamically stable throughout procedure.
At end of surgery, neuromuscular blockade was reversed with neostigmine and
glycopyrrolate. Trachea was extubated in prone posture itself as requested by surgeons to
avoid pressure on flap after patient was awake; Ondansteron 4mg IV was used as
antiemetic.
Post operatively patient was shifted to post anaesthesia care unit with O2
supplementation and then towards after 2 hrs. Patient was discharged from hospital on 7th
post operative day with psychiatry referral.
Discussion: Neuroleptic Malignant Syndrome (NMS) was first described by Delay et al during
early trials of haloperidol. The incidence is estimated to range from 0.02–2.4% with The
Diagnostic criteria are:
• Administration of neuroleptics
• Hyperthermia (> 38oC)
• Muscle rigidity
• Five of following: mental status change, tremor, tachycardia, incontinence, labile
blood pressure, metabolic acidosis, tachypnoea/hypoxia, CPK elevation,
diaphoresis/sialorrhea, leukocytosis.
• Exclusion of other central and systemic causes of hyperthermia.
 Although NMS has a variable onset and sometimes evolves rapidly, rigidity and
altered mental status usually occur early, followed by autonomic changes and
hyperthermia. No laboratory tests are pathognomonic of diagnosis. Serum creatine kinase
is frequently elevated reflecting rhabdomyolysis, with resultant risk of myoglobinuric renal
failure. CT scan brain and cerebrospinal fluid examination and sepsis evaluation are negative
in NMS and allow for   the exclusion of other causes of fever and neurological deterioration.
Other frequently described laboratory abnormalities include metabolic acidosis, hypoxia,
low serum iron, electrolyte abnormalities, elevated serum catecholamines and
coagulopathies
Differential Diagnosis of NMS: Infectious encephalitis4,5, structural lesion of brain, rare
cases of status epilepticus6, lethal catatonia7, heat stroke, endocrinopathies, drugs,
autoimmune disorders, thyrotoxicosis, phaeochromocytoma, malignant hyperthermia,
serotonin syndrome. Volatile anaesthetics and succinylcholine are associated with
malignant hypertherma during surgery, which can be confused with NMS if neuroleptics are
administered

The basic management of NMS remains risk reduction, early diagnosis, cessation of
neuroleptic medications and institution of Intensive, medical and nursing care.
Benzodiazepines, bromocriptine, amantadine or other dopamine agonists may be a
reasonable next step in patients with moderate symptoms of NMS. Dantrolene may be
beneficial in cases of NMS with extreme rigidity and hyperthermia. Electro convulsion
therapy (ECT) is used if NMS is refractory to other measures or who remain psychotic after
NMS   is resolved. Since a common pathophysiology has been suggested between NMS and
malignant hypertherima (MH) the possibility that patients with a history of NMS may be
vulnerable to developing MH is an important factor when considering general anaesthesia,
especially succinylcholine administration. To date, there is no report in the literature of
(MH) as a complication of ECT in NMS patients. However, until the association between
NMS and MH is conclusively disproved, careful metabolic monitoring of general anaesthesia
is necessary.
Conclusion: Neuroleptics are highly effective medications that have achieved wide spread
use in medicine and psychiatry. However they have been associated with NMS in about 0.2
percent of patients. Awareness of diagnosis, cessation of medications, early medical
intervention and consideration of specific remedies can reduce morbidity and mortality
when NMS occurs. This case report has been published to increase familiarity with the
diagnosis and management of this unusual but fascinating drug reaction and anaesthetic
management of a incidental surgery in a patient of NMS.
References:  
1. Delay J., Pichot P., Lemperiere T, Elissade B., Peigne F. Un neuroteptique majeur non
phenothiazine et non reserpinique, L’haloperidol dans Le traitment des psychoses.
Annales Medico-Psychologique 1960 ; 118:145 – 152.
2. Ananth J Parameswaran S., Gunatilake S. et. al.; Neuroleptic malignant syndrome
and a typical antipsychotic drugs. J. Clin Psychitary 2004 Apr: 65 (4): 464- 70.  
3. Velamoor VR, Normal RM, Caroff SN, Mann SC, Sullivan KA, Antelo RE. Progression of
symptoms in Neuroleptic Maligant Syndrome. Journal  of Nervous and Mental
Disease : 1994 ; 182: 168 – 173.
4. Caroff SN, Mann SC. McCarthy M, Naser J., Rynn M, Morrison M. Acute infectious
encephalitis complicated by Neuroleptic Malignant Syndrome. Journal of Clinical
Psychopharmacology 1998 ; 18 : 349-351
5. Caroff SN, Mann SC, Gliatto MF, Sullivan KA, Campbell EC. Psychiatric Manifestations
of acute viral encephalitis. Psychiatric Annals 2001: 31; 193-204.
6. Caroff SN, Mann SC, Neuroleptic Malignant Syndrome. Medical clinics of North
America 1993; 77: 185-202
7. Mann SC, Caroff SN, Bleier HR, Welz WKR, Kling MA, Hayashida M. Lethal catatonia ;
1986; 143: 1374 – 1381
8. Keck PE Jr. Arnold LM. The serotonin syndrome. Psychiatric Annals 2000 : 30 : 333 –
343
9. Caroff SN, Rosenberg H., Mann, Campbell EC, Gliatto MF, Sullivan KA, Neuroleptic
Malignant Syndrome in the perioperative setting. American Journal of
Anesthesiology 2001,: 28 ; 387 – 393
10. Davis JM, Caroff SN, Mann SC. Treatment of neuroleptic malignant syndrome
Psychiatric Annals 2000; 30: 325 – 331.  
11. Caroff SN, Mann SC, Keck PE, Jr. Specific treatment of the neuroleptic malignant
syndrome. Biological Psychiatry 1998; 44: 378 – 381.   The Indian Anaesthetists’ Forum – (http://www.theiaforum.org)                    Online ISSN 0973-0311
January 2010(4)
Agrawal P,Agrawal A, Singh I: Neuroleptic Malignant Syndrome and Anaesthesia : A Case Report  5
12. Denborough MA, Collins SP, Hopkinson KC. Rhabdomyolysis and malignant
hyperpyrexia. Br Med J 1985; ii: 1878
13. Tollefeson G. A case of neuroleptic malignant syndrome in vitro muscle comparison
with malignant hyperthermia J. Clin Psychopharmacol 1982; 2: 266 – 70  

Stiff Person Syndrome

Stiff Person Syndrome and Anesthesia: Case Report

1. Jans Bouw, MD*, 
2. Karin Leendertse, MD*, 
3. Marina A. J. Tijssen, MD PhD†and 
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.

 

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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.

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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.

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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 GABA_A 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.

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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.

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We thus conclude that the prolonged muscle relaxation can be explained by the enhancement of general anesthetics via GABA_B action on synaptic transmission (17). This case demonstrates a potential danger in combining baclofen with volatile anesthetics in patients with SPS.

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