Management of a case of ankylosing spondylitis for total hip replacement surgery with the use of ultrasound-assisted central neuraxial blockade.

Management of a case of ankylosing spondylitis can be very challenging when the airway and the central neuraxial blockade, both are difficult. Ultrasound-assisted central neuraxial blockade may lead to predictable success in the field of regional anaesthesia. We present a young patient with severe ankylosing spondylitis where conventional techniques failed and ultrasound helped in successful combined spinal-epidural technique for total hip replacement surgery.

INTRODUCTION

Ankylosing spondylitis (AS) is a chronic inflammatory disease of the axial skeleton and peripheral joints.[1] Hip replacement surgery helps in restoring the functional capabilities of patients to a large extent.

AS has always been a challenge to the anaesthesiologist due to either a difficult airway or a seemingly impossible central neuraxial blockade. Fibreoptic bronchoscopy has been used successfully to secure the airway[2] as central neuraxial blocks may not be easy to perform in such cases. The use of ultrasound (US)-guided central and peripheral nerve blocks has helped in achieving predictable success.[3]

We report a case of a young male who suffered from severe AS and was posted twice for total hip replacement (THR), one side at each time. The ease and reliability of US-assisted central neuraxial block is highlighted in this report.

CASE REPORT

A 26-year-old male, known case of severe AS, symptomatic for the last 6 years, was listed for THR (right). He had a classical bamboo spine with no mobility of cervical or thoraco-lumbar spine [Figure 1]. Both the hip joints were totally fixed and he was unable to even sit for the last 3 years. The cardiac and respiratory systems were normal on examination and his haematological and biochemical parameters were also within normal limits.

Figure 1

Antero-posterior radiograph of lumbo-sacral spine. Fusion of sacroiliac joints, vertebrae with bridging syndesmophytes (shown by arrows), dagger sign (ossification of anterior longitudinal ligament and interspinous ligament) and tram track sign (syndesmophytes and ossified ligaments looking like tram tracks) are seen

Airway was anticipated to be difficult because of the lack of any extension of cervical spine and mouth opening of about 2.5 cm. A difficult airway cart was kept ready along with a flexible fibreoptic bronchoscope.

Written informed consent was obtained for both general and regional anaesthesia and the patient was fasted adequately. The plan was to first attempt a spinal and/or epidural block, and in case of difficulty or failure, the alternative was a fibreoptic bronchoscope assisted awake intubation.

Lumbar punctures were attempted at different spinal levels by median or paramedian approach by two experienced anaesthesiologists, but they failed. The positioning of the patient for the puncture was extremely difficult as there was no flexion at the hip joints. The patient could not sit and could only lie straight in lateral position without bending at the hip at all. Awake fibreoptic assisted intubation was done by standard technique and general anaesthesia was administered for the surgery. Analgesia was maintained with opioids and nonsteroidal anti-inflammatory drugs (fentanyl and diclofenac intravenous) during the perioperative period. Three months later, the same patient was listed again for THR on the other side. This time, we planned a pre-procedural USG in the preoperative room to assess the possibility of a central neuraxial blockade. Mindray M5 Hand-carried Diagnostic Ultrasound System (Shenzhen Mindray Bio-Medical Electronics Co., Ltd. Shenzhen, China) with linear array transducer probe 7L4s (5-10 MHz) was used to visualise the spine with patient in lateral position. The spine was scanned from L2 spinous level downwards both in the transverse midline (TM) plane and parasagittal (PS) planes on both sides.

The interlaminar spaces were very narrow and poorly visualised because of hyperechoic shadows at all levels in the PS planes except at L2-3 where they could be distinguished more clearly [Figure 2a]. With the transducer placed at the point of best visualisation, a line was drawn perpendicular to the midline of the transducer with the help of a marker pen [Figure 2b]. The transducer was now placed in the TM plane and a complete scan was done. The ligamentum flavum/duramater complex and the posterior longitudinal ligament overlying the posterior aspect of the posterior vertebral body could be distinguished only at L2-3 level. A similar line was drawn perpendicular to the midline of the transducer. The point of insertion of the spinal needle was taken as the intersection of these two lines. The patient was taken to the operation suite and the standard monitors were placed. The patient was turned to left lateral position and after thorough asepsis, a 17-G Tuohy needle (a combined spinal-epidural set BD, Becton, Dickinson and Company, NJ, USA) was inserted from the marked point. The epidural space was identified with a loss of resistance to saline and then a 25-G Whitacre needle was introduced through it. The subarachnoid space was reached at about 5 cm from skin in a single attempt. After a free flow of cerebrospinal fluid, 2.5 ml of 0.5% hyperbaric bupivacaine was injected. A 19-G epidural catheter was advanced through the epidural needle and fixed to the skin at 9 cm.

Figure 2

(a) Position of ultrasound probe in left parasagittal plane with a line marked perpendicular to midline. (b) Parasagittal view of ultrasound scan at L2-3 space showing the two sawtooth-shaped laminae (arrows) and the space between them

The sensory and motor blocks were adequate and the patient remained haemodynamically stable intraoperatively. The surgery lasted for 2 h following which an epidural infusion was started with 0.125% bupivacaine and 2 mcg/ml fentanyl at 6 ml/h and continued for 72 h postoperatively. Diclofenac 1 mg/kg intravenous was given twice a day and the patient was comfortable in the postoperative period.

DISCUSSION

AS is a chronic inflammatory disease of the axial skeleton in which the inflammatory process starts from the sacro-iliac joints and spreads cephalad to affect the spine up to the cervical level along with costo-vertebral joints. There may be stiffness of the axial skeleton with ossification of axial ligaments and sacroiliac joints, along with decreased intervertebral spaces causing spinal rigidity.[1] The formation of bony bridges (syndesmophytes) between vertebrae results in a classic “bamboo spine” appearance. These changes make administration of both general and regional anaesthesia difficult.

Regional anaesthesia offers many advantages over general anaesthesia in these patients,[1] but central neuraxial blocks are known to be difficult, though not impossible, depending upon the severity of the disease. They have been underutilised in the past and there are only a few reports of successful spinal and epidural puncture in patients with AS.[4] In the largest review of 80 patients over a 10-year period, Schelew et al. planned spinal anaesthesia in only 16 patients out of which they reported success in 10.[5] A paramedian approach may be easier because of the midline ossification of the interspinous ligaments. Taylor's approach, a paramedian approach to L5-S1 interspace, may also be better to access in some cases.[6]

In our patient, multiple attempts failed during the first surgery which prompted us to plan a pre-procedural US the next time. There are reports on increased incidence of epidural haematoma and total spinal anaesthesia due to multiple attempts at puncture and common use of nonsteroidal anti-inflammatory drugs in cases of AS.[78] US adds safety to the procedure as the adjoining blood vessels or neural structures can be protected from untoward injuries, besides being non-invasive.

US may also be a useful preoperative assessment tool for assessing the feasibility of central neuraxial blockade when technical difficulty is anticipated.[39-11] Chin et al. demonstrated accurate location of L5-S1 intervertebral space with US when several attempts on lumbar puncture had failed in the same patient.[9] Karmaker et al. could access the epidural space successfully in one attempt in 14 out of 15 cases using real-time US.[12]

This case also shows that US guidance can be a very useful tool in patients where technical difficulty in central neuraxial block placement exists. Patients with AS represent one such group. Experience in using US may, however, require some practice and thorough understanding of the subject.