Blog with interesting cases and/or problems related to anesthesia with discussion based on best evidence in the literature.

January 1, 2016

Emergent case in patient Post Polio Syndrome

A 67 year old male presented urgently to the OR on Christmas Day for evacuation of blood clots from the bladder and ongoing renal dysfunction secondary to hydronephrosis.

The patient appeared debilitated with near complete atrophy of the lower extremities.  There also appeared to be bone deformities with flexion contractures of the upper and lower extremities.

The patient had a reported PMH of diabetes, past CVA, HTN, and polio with post polio syndrome.

The patient had eaten breakfast about 8:30 in the morning and now (at 14:00) required emergent evacuation of blood clots from the bladder.  It was decided to proceed to the OR under GETA.

The patient had come to the ER a few days previous for treatment of cellulitis of his groin area and was on antibiotics.  During the hospitalization, he had received a foley catheter that was removed. This lead to acute urethral obstruction and significant bladder distention.

Since this patient was considered a full stomach by myself, I elected to perform a general anesthetic using RSI.  Given his reported history of post polio syndrome, there was concern that he might have a hyperkalemic response to succinylcholine.    I administered 100 mcg fentanyl, 2 mg of versed, 130 mg of propofol and 80 mg of succinylcholine for intubation.  Intubation was uneventful, and the patient was maintained with sevoflurane.  The surgeon performed a cystoscopy with evacuation of a large amount of clot. The patient was extubated in the OR and went to the PACU with no problems noted.

Post polio syndrome was only first recognized in the 1970's and 1980's as patients from the 1950's who had contracted polio, improved and then suffered a recrudescence and sought medical care.

Polio is a single stranded picornavirus  infection that has been described as one that attacks and destroys the motor neurons lying in the anterior horn of the spinal cord.  The severity is variable, from complete respiratory failure and paralysis to a mild fever that lasts a few days.  However, it has also been noted that histopathologically, there is evidence of damage to the neurons located in the brain, predominantly in the brain stem and cerebellum.  These sites include the reticular formation, vestibular nuclei, and the roof nuclei of the cerebellum.

Post polio syndrome(PPS) symptoms include weakness, fatigue (generalized and muscular), atrophy, and pain.  Unfortunately, the symptoms are vague and non specific and therefore, it is a diagnosis of exclusion in patients who have a history of paralytic polio with residual motor neuron loss followed by a period of recovery and then stability of 15 years or more prior to a subsequent new onset of weakness or abnormal muscle fatigue.

Unfortunately, there are very few case reports of anesthesia in patients with PPS. Two cases reported complications. The first was a 79 year old patient who suffered post operative ventilatory failure.  The second, was a 51 year old patient having foot surgery.  The patient suffered a cardiopulmonary arrest 1 hour post op in her hospital room.  She did not recover.  It was presumed to be related to respiratory obstruction due to oversedation from opioid medication.

There are a number of considerations when anesthetizing a patient with PPS.  Respiratory function can be compromised in these patients. One study demonstrated that 42% of these patients develop new breathing problems requiring intervention.  A history  suggestive a decreased respiratory reserve should prompt further evaluation with chest x ray and spirometry.  If VC is less than 50% of predicted or less than 1500 ml, then complete pulmonary function testing should be considered.  These patients also need to be screened carefully for symptoms of OSA, and a sleep study considered if there is concern in this regard.  Furthermore, these patients often develop laryngeal dysfunction, ranging from laryngeal muscle weakness to unilateral or bilateral vocal cord paralysis. This makes these patient at high risk for post anesthetic apnea, aspiration, and vocal cord paralysis.

Regional anesthesia may be a good choice despite the possibility that patients have existing neuromuscular deficits.  There are reports of adverse effects due to regional anesthesia.  A series of  patients in Brazil was followed for 22 months after neuraxial anesthesia in patients with PPS [1]. There was no evidence of worsening of symptoms in this retrospective review. There are no large scale studies of regional anesthesia in this patient population, but it is likely to be safe.  Using epidural anesthesia may be preferable to spinal anesthesia if a neuraxial technique is chosen.  Animal studies have determined specific intrathecal concentrations of local anesthetics that are lethal for neurons.  Undoubtedly, there are a large number of unhealthy, or marginal motor neurons in the PPS patient and it is very clear that PPS patients have fewer motor neurons than normal.  These fewer motor neurons are likely less healthy, or are impacted by a larger metabolic demand because they must supply a larger motor unit endplate as part of the natural pathogenesis of PPS. In theory, these motor neurons could be more sensitive to drug effects and its very likely that the threshold for local anesthetic neurotoxicity is lower.

If general anesthesia is chosen there are number of considerations.  The room should be warmed and a warming blanket used due to the high degree of cold intolerance by these patients.  If using NDMB, pre blockade twitch strength should be evaluated as it is often depressed at baseline.  There is evidence to suggest that patients with a remote history of polio have significantly increased sensitivity to NDMB [2,4].  Complete avoidance would be preferable if possible.
Although there is concern about the potential for hyperkalemic reponse to succinylcholine in patients with chronic neuromuscular disorders we don't have any specific evidence that this is true for PPS. Mantz et al reported the safe use of succinylcholine in a woman with PPS for cesarian delivery [3]. In addition, a series of six patients was reported who received succinylcholine with PPS and significant muscular atrophy leading to severe scoliosis requiring harrington rod placement.  All six patients were females with longstanding PPS and paralytic atrophy of the limbs.    There was no reported ill effects in this series.  The authors suggested that since all of these patients had received a defasciculating dose of 20 mcg/kg  of pancuronium, that this may have prevented activation of upregulated ACHrs and thus prevented hyperkalemia.  This suggestion is based on an article from 1976 looking at the prevention of the normal potassium increase that occurs when a prefasciculating dose of pancuronium is administered to normal healthy patients.  This may not be relevant to the current discussion. However, it is clear that in patients with a hyperkalemic reponse to succinylcholine, there is resistance to NDMB due to the upregulation of nicotinic acetylcholine recpetors (nACHr).  In patients with PPS, it is typical that we observe the opposite (increased sensitivity to NDMB).  This could lead one to speculate that upregulation of nACHr is not part of the normal pathophysiology of PPS.

After lower or upper motor neuron denervation and in certain pathologic states (eg burns, sepsis, immobilization, chronic muscle relaxant therapy or botulism, loss of muscle electrical activity), the immature or alpha 7 type may proliferate in a way that they spread across the entire muscle belly. A hyperkalemic response to succinylcholine may result from this very large increase in nACHr.  These so called extrajunctional receptors are not composed of the typical proteins that make up junctional nACHr. Typical nACHr in adults are composed of five subunits arranged to form a pore as seen below. These are referred to as the mature type of nACHr.  These two subtypes immature and alpha 7 have different characteristics and may account for some of the clinical findings in patients with a proliferation of extrajunctional receptors such as resistance to NDMB and the large hyperkalemic response to succinylcholine. Furthermore, these characteristics, i.e. depolarization at 1/100th the dose for the normal adult receptors and 10 fold increased mean channel open time, indicates that attempting to use a smaller dose of succinylcholine to avoid hyperkalemia, will not be successful.

Above, I referred to an article where it was suggested that perhaps the use of a small dose of a NDMB might prevent a hyperkalemic response to succinylcholine.  There is evidence to suggest that in normal patients, the normal 0.5 to 1.0 mEq rise in K+ seen when given succinylcholine may be prevented with a defasciculating dose of a NDMB. However, we know that in states where extrajunctional nACHr have prolifereated, the fetal and alpha 7 type predominate.  One of many different characteristics of these receptors is their lack of sensitivity to NDMBs. Therefore, it would not be expected that a typical defasciculating dose would prevent hyperkalemia since these aberrant receptor subtypes are less likely to effectively bind to our non depolarizers.

It has been demonstrated that in PPS, there is residual lesions involving the reticular activating system.  Because the reticular activating system is a theoretical site of action for most anesthetic agents, it would be prudent to cautiously titrate anesthetics to the patients response.  In the current case, the patient did not show an increased sensitivity to sevoflurane, and emergence was uneventful.  The idea that these patients are more sensitive to anesthetics is still theoretical.

Complications reported in this patient population have been reported in the post operative period.  Indeed, this may really be the time period where careful patient monitoring must occur as these patients are likely to have problems with obstruction due to weakness in the pharyngeal dilator muscles and increased sensitivity to opioid pain medications.

In conclusion, this is a report of use of succinylcholine for RSI in a patient with post polio syndrome and a full stomach coming for emergent surgery with no apparent adverse affect.  This case adds to a limited number of cases where succinylcholine has been safely administered.  The use of succinylcholine remains controversial in this setting, however, there is some evidence to suggest that resultant hyperkalemia is unlikely.  This evidence includes several case reports along with the clinical appearance of higher sensitivity to NDMB as opposed to the expected resistance to NDMB seen in denervation conditions where hyperkalemia has been reported after succinylcholine.

1. Rezende DP, Rodrigues MR, Costa VV, Arci EC, and Saraiva RA. Patients with sequelae of poliomyelitis. does the anesthetic technique pose risk. Revista Brasileira de Anestesiologia. 2008. 58(3).

2. Gyermek L. Increased potency of nondepolarizing muscle relaxants after poliomyelitis.  J Clin Pharmacol 1990; 30:170-3.
3.  Wernet A, Bougeois B, Merckx P, Paugam-Burtz C, Mantz J.  Successful use of succinylcholine for cesarean delivery in a patient with postpolio syndrome.  Anesthesiology. 2007;107:680-1.
4. Suneel PR, Sinha PK, Unnikrishnan KP, Abraham M.  Anesthesia for Craniotomy in a patient with previous paralytic polio. J Clin Anesth. 2008. May; 20(3):210-3.



Anonymous said...

You could use alfentanil or remi to provide RSI conditions. I have done that on call for patients that were full stomachs, had contraindications to succinylcholine and were having a very short operation.

Jordan said...

Thanks for sharing this case. Good to see what people are doing involving post polio syndrome.