post - herpetic neuralgia is a serious complication of herpes zoster that causes critical pain to patients even after skin lesions have healed .
epidural blocks are achieved either by single injection of local anesthetic through the epidural needle or as continuous block by infusion pump through an epidural catheter .
the epidural catheter can be inserted not only in thoracic and lumbar vertebra , but also in cervical vertebra .
knotting of epidural catheters is very rare , but knotting in lumbar epidural catheters has been reported in a number of studies , and most of these cases involved removal difficulty .
we report a case in which we inserted a cervical epidural catheter in a patient who was experiencing severe post - herpetic neuralgia and then removed the knotted catheter without complications .
a female patient , 73 years old , was diagnosed with herpes zoster and received medical treatment at another medical clinic .
however , when her serious pain did not subside after treatment , she visited our pain clinic .
her pain was severe , 10/10 on the numeric rating scale ( nrs ) at the first visit .
she appeared to have herpes zoster involving the fifth cervical spinal nerve root on the right and was diagnosed with post - herpetic neuralgia .
we explained our plan to perform a cervical epidural block along with medical treatment and received informed consent .
the patient was instructed to flex her neck so that her interlaminar space was easily distinguished .
skin over the c6 - 7 interlaminar space was sterilized with betadine solution and topically anesthetized with 2 ml of 2% lidocaine . using the midline approach
, we checked the epidural space through a 20-gauge tuohy needle using the loss of resistance method ; after assuring that there was no cerebrospinal fluid or blood aspirated , 5 ml of 1% mepivacaine and 2 mg of dexamethasone were injected .
immediately after the injection , the patient reported that her pain temporarily decreased ; but after about 40 minutes , she said the pain was again as severe as it used to be .
we explained the use of an epidural block with epidural catheter insertion and received agreement from the patient to proceed .
the epidural space was checked using an 18-gauge tuohy needle at c6 - 7 using the same technique as for the cervical epidural block .
the depth of the epidural space from the skin was 5.2 cm . a 20-gauge epidural catheter ( smiths medical asd , inc .
keene , usa ) was advanced by 7 cm cephalad through the epidural needle ; after the needle was removed , the catheter was pulled out by 2 cm and inserted 5 cm from the epidural space .
after insertion of the epidural catheter and confirming that no blood or cerebrospinal fluid had been pulled in , 3 ml of 1% mepivacaine was injected .
the patient reported that her pain was subsiding , so she was given 2 ml of 0.18% ropivacaine per hour through an infusion pump .
we prescribed pregabalin 225 mg , tramadol 150 mg , and amitriptyline 10 mg per day , and the patient was discharged .
she visited our clinic every day for the next four days and received additional injections of 5 ml of 1% mepivacaine through the epidural catheter , maintained by infusion pump .
after this , she reported that the pain was decreased to 56 on nrs , and that she could finally sleep at night . on the fifth day , she reported her pain to be 34/10 on nrs , and that she wanted to remove the epidural catheter , while remaining on her prescribed medication .
we attempted to remove the catheter from the patient in a seated posture ; however , after it was pulled out about 3 cm , there was resistance , and it stopped moving .
when asked if there was any pain or discomfort of the neck , the patient answered that there was not . after asking the patient to repeat bending and then straightening her neck a few times and pulling the catheter out with slightly stronger force , the catheter suddenly snapped out .
the patient reported no pain in the neck or arm , so our medical team sterilized the area where the catheter had been installed and applied a dressing .
when the removed catheter was thoroughly examined , a knot was discovered 1.5 cm from the tip ( fig .
side effects or complications of epidural catheter placement include unsuccessful catheter placement , intrathecal or intravascular placement , catheter damage , knotting , and difficult removal .
knotting is a very rare complication in epidural catheters , and the actual incidence is difficult to determine because most of the documentation is provided in the form of case reports .
therefore , cases of knotting have been reported primarily in lumbar epidural catheters , with only one case involving a thoracic epidural catheter . in 12 cases ,
the knots arose less than 3 cm from the catheter tip , near the distal end . in one case ,
a double knot was found 1.5 cm to 3 cm from the tip of the catheter , while another case involved a butterfly - like knot 5 cm below the catheter tip . in our case
, the knot was located 1.5 cm below from the catheter tip after cervical epidural catheter placement , a condition that has never been reported previously .
the insertion of epidural catheters is performed through tuohy needles , with the clinician threading the epidural catheter into the epidural space and subsequently withdrawing the catheter through the desired level in the epidural space .
the longer is the distance the catheter is inserted from the epidural space , the greater is the chance of knotting .
therefore , several authors have recommended that the length of the catheter passed beyond the tip of the needle should be limited to reduce this risk .
it has been recommended that the length of catheter insertion not exceed 5 cm , and less than 34 cm is considered optimal to prevent knotting .
however , knots in epidural catheters have been reported even when no more than 3 cm had passed in the epidural space . in our case ,
when removing an epidural catheter , steady and gentle firm traction must be applied in the same direction as when the catheter was inserted .
if the catheter begins to stretch too much or the patient complains of pain or paresthesia during withdrawal , the traction should be stopped at once . in most cases ,
difficult removal of epidural catheters occasionally occurs , and several maneuvers have been recommended in response : ( 1 ) slow , continuous , and steady pressure on the catheter to avoid catheter breakage ; ( 2 ) reapplication of force and traction several hours later ; ( 3 ) having the patient adopt the same position as when the catheter was inserted ; ( 4 ) having the patient adopt the lateral decubitus position ( as greater force is required to remove epidural catheters in the flexed sitting position than in the lateral position ) ; and ( 5 ) attempting removal after injection of normal saline through the catheter , which may also assist in determining whether the catheter is knotted . if necessary , radiological images can be checked while injecting radiopaque dye through the catheter , and computer tomography can also help to clarify the image .
gadalla reported that catheters were more successfully removed with patients under general anesthesia with muscle relaxation .
surgical removal can be also applied when a patient shows neurologic signs during traction or pieces of broken catheter are detected . after removing an epidural catheter ,
if a catheter fragment is retained in the body , it remains debatable whether the fragment should be removed surgically .
some experts recommend that , as catheters are sterile and unlikely to cause neurologic damage , fragments should be left in situ , especially if no neurologic sequelae are noted .
surgical removal may increase the risk of neurologic damage due to infection , fibrosis , or mechanical neural irritation .
however , some reports have demonstrated adverse effects after leaving the sheared catheter in situ such as radiculopathy , weakness , granuloma formation , and fibrosis as a result of long - term retention of epidural catheters . in the present report
our patient did not complain of discomfort during removal of the catheter , but mild resistance was experienced when our medical team attempted to pull out the catheter .
the patient was placed into the same seated posture as she had assumed when the catheter was inserted and bent her neck down and up a few times , and the catheter was then successfully removed without any complications .
a knot was found 1.5 cm from the tip of the catheter , which itself was 5 cm long .
it is normally recommended that the length of epidural catheters be less than 5 cm , while catheters less than 34 cm in length are considered ideal to prevent possible knotting .
 epidural block is achieved either by single injection of local anesthetic through an epidural needle or as a continuous block by infusion pump through an epidural catheter . 
 complications associated with epidural catheters include breakage , entrapment , and knotting . 
 knotting of epidural catheters is very rare , but knotting in lumbar epidural catheters has been reported in a number of studies , and most of these cases involved removal difficulty . 
 we report a case in which we inserted a cervical epidural catheter in a patient who was experiencing severe post - herpetic neuralgia and then removed the knotted catheter without complications . 
INTRODUCTION
CASE REPORT
DISCUSSION