Lateral Decubitus Transradial Carotid Artery Stenting in Ankylosing Spondylitis: A Novel Positioning Strategy

Introduction

Carotid artery stenting (CAS) is conventionally performed in supine position [1]. However, patients with ankylosing spondylitis (AS) and severe spinal rigidity cannot tolerate supine positioning due to fixed “bamboo spine”, while general anesthesia poses significant risks from difficult airway management [2]. Compared with carotid endarterectomy (CEA), CAS offers the advantage of avoiding general anesthesia and neck extension, making it particularly suitable for patients with severe AS. Herein we describe successful transradial CAS performed in lateral decubitus position under local anesthesia in a patient with severe AS, demonstrating that alternative positioning can provide safe and effective treatment for this challenging population.

Case Report

A 70-year-old man with 40-year history of ankylosing spondylitis (AS) presented with recurrent cerebral infarction, manifesting as recurrent episodes of right-sided limb weakness and slurred speech, consistent with transient ischemic attacks. These events were attributed to artery-to-artery embolism from the stenotic right internal carotid artery, which was considered the most likely mechanism underlying the recurrent infarctions.

Cervical computed tomography angiography revealed severe right internal carotid artery stenosis (NASCET 80%). Due to complete spinal rigidity (“bamboo spine”), the patient could not tolerate supine positioning beyond 2 min, precluding conventional carotid CAS. Furthermore, the severe cervical spine rigidity and fixed flexion deformity associated with AS significantly increase the risks of both surgical CEA under general anesthesia – due to anticipated difficult airway management and hemodynamic instability – and conventional supine-position CAS. These considerations collectively justified the use of the present novel approach.

Prior to the procedure, the patient was premedicated with dual antiplatelet therapy (aspirin 100 mg and clopidogrel 75 mg daily for 5 days). Intravenous heparin (70 IU/kg) was administered at the start of the procedure. Local anesthesia was achieved with 2 mL of 2% lidocaine at the radial artery puncture site, with no sedation administered.

In this positioning strategy, the patient lay on the right side with the right arm extended anteriorly on an arm board, allowing radial artery access. Cylindrical rolls fashioned from surgical towels supported the axilla and trunk, maintaining a 45° angle (Figure 1A, 1B). The patient tolerated the right lateral decubitus position well throughout the entire procedure. No significant back pain was reported during positioning. No additional analgesics or sedatives were required for position maintenance. A preoperative positioning rehearsal in the DSA suite was conducted prior to the procedure to confirm patient tolerance and optimize C-arm geometry.

Figure 1C and 1D show pre- and post-intervention digital subtraction angiography (DSA). C-arm angulation (LAO 15°/Cranial 3°) was optimized through systematic adjustment to visualize the carotid bifurcation despite lateral positioning. The LAO angulation was increased incrementally to compensate for the rotational offset introduced by the lateral patient position, and cranial tilt was minimized to avoid vessel overlap. A 6F sheath was placed in the right radial artery via standard Seldinger technique. A 0.035-inch hydrophilic guidewire was advanced under fluoroscopic guidance through the right subclavian artery, ascending aorta, and into the common carotid artery. A 6F guide catheter was then positioned in the common carotid artery. The XACT stent (6–8–40 mm; Abbott Vascular) was deployed under arm board distal embolic protection. Procedure time was 32 min with 30% residual stenosis and no complications.

The patient maintained consciousness throughout, allowing real-time neurological monitoring. Continuous neurological assessment was performed by verbal communication with the patient during the procedure, including evaluation of speech, hand grip strength, and responsiveness. No neurological deterioration was detected intraoperatively. He was discharged on day 3, showing significant improvement in his presenting symptoms, with no recurrence of limb weakness or speech disturbance compared to the preoperative baseline. Three-month follow-up CTA confirmed a patent stent without restenosis.

Discussion

ANKYLOSING SPONDYLITIS AS A PROCEDURAL RISK FACTOR:

AS is a chronic inflammatory seronegative spondyloarthropathy characterized by progressive spinal fusion and extra-articular manifestations [5]. Relevant procedural risks in AS patients include: (1) airway management difficulty due to cervical spine ankylosis and temporomandibular joint involvement, increasing the risk of failed intubation under general anesthesia; (2) hemodynamic instability related to associated cardiac involvement (aortitis, conduction abnormalities); (3) positioning intolerance, as fixed spinal flexion deformity prevents supine or hyperextended positioning required for conventional CAS and CEA; and (4) atlantoaxial instability in some patients, which can be exacerbated by neck manipulation during intubation.

TRANSRADIAL ACCESS AND LATERAL POSITIONING:

Transradial access for CAS has gained increasing acceptance as an alternative to transfemoral and transcervical approaches, offering advantages including lower access-site complication rates, earlier ambulation, and reduced bleeding risk [6]. The present case extends this approach by combining transradial access with lateral decubitus positioning, which is to the best of our knowledge a combination not previously described in the literature for CAS in AS patients.

The technical feasibility of this approach relies on several key adaptations: careful C-arm angulation adjustment (LAO 15°/Cranial 3° in this case) to account for the rotational offset of the lateral position; use of cylindrical towel rolls to stabilize the patient and maintain a reproducible 45° lateral tilt; and a preoperative positioning rehearsal to confirm both patient tolerance and fluoroscopic adequacy prior to arterial access.

NEUROLOGICAL MONITORING UNDER LOCAL ANESTHESIA:

The use of local anesthesia without sedation in this case enabled continuous real-time neurological monitoring, a recognized advantage of awake CAS procedures. The patient remained communicative throughout, allowing immediate detection of any intraoperative neurological change. However, it should be acknowledged that this monitoring strategy has inherent limitations: it is dependent on patient cooperation and communication ability, and may be unreliable in patients with pre-existing cognitive impairment, severe pain, or anxiety requiring sedation.

LIMITATIONS:

This report has several limitations. First, it represents a single case, and the generalizability of this technique to a broader AS population, particularly those with more severe deformities, bilateral carotid disease, or significant cardiac involvement, remains to be established. Second, the follow-up period was limited to 3 months; longer-term data on stent patency and restenosis rates are needed. Third, the specific C-arm angulation and positioning parameters may require individualization based on patient anatomy and the degree of spinal deformity. Future multicenter studies or registry data would be valuable in establishing standardized protocols for this technique. Future studies with longer follow-up periods (≥6–12 months) are warranted to evaluate stent durability and restenosis rates.

LEARNING POINTS:

Lateral decubitus positioning is feasible for transradial carotid artery stenting when supine positioning is contraindicated due to severe spinal rigidity. Local anesthesia without sedation permits continuous real-time neurological assessment and avoids difficult intubation in ankylosing spondylitis patients with fixed cervical spine deformity; however, the reliability of bedside neurological assessment may be limited in patients with altered consciousness or communication difficulties, which is a potential limitation of this approach. Preoperative positioning rehearsal in the DSA suite is essential to confirm patient tolerance and optimize C-arm geometry prior to arterial access.

Conclusions

Lateral decubitus positioning combined with transradial access under local anesthesia is a safe and technically feasible strategy for performing CAS in patients with severe AS who cannot tolerate conventional supine positioning. The successful outcome in this case demonstrates that careful preoperative planning, including positioning rehearsal and C-arm geometry optimization, is essential to procedural success. This approach effectively circumvents the risks of general anesthesia in a population with known airway management challenges, and may serve as a replicable template for similar high-risk cases at other institutions. Further studies with larger cohorts and longer follow-up are needed to establish standardized protocols.