Introduction

Ischemic monomelic neuropathy (IMN) is a rare complication following arteriovenous fistula (AVF) surgery that is characterized by acute onset of pain, motor weakness, and sensory changes without critical ischemia [1]. Due to decreased distal arterial flow caused by shunting from the artery to the vein after the vascular access surgery, underfilling of the vasa nervorum can occur, leading to multiple axonal losses involving the sensory and motor nerves [2]. Here, we present a case of IMN in a patient with end-stage kidney disease (ESKD) that developed after brachiocephalic AVF surgery.

Case

Ethics statement: Written informed consent was obtained from the patient to participate in the study.

A 61-year-old man with diabetic ESKD was admitted for left brachiocephalic AVF surgery. On postoperative day one, the patient exhibited no neurological symptoms except for pain and mild swelling at the surgical site. At that time, the patient’s radial pulse was palpable and his hand was warm. Two days after the surgery, he complained of left-hand pain and numbness. His symptoms gradually worsened from postoperative day three onward. He could not raise his hand, which became pale and numb, and his handgrip became progressively impaired (Fig. 1). Nonetheless, his radial pulse remained palpable and the overlying skin remained intact.

A nerve conduction study (NCS) was performed, revealing a reduced compound muscle action potential (CMAP) in the left ulnar nerve and no CMAP in the left median nerve, both above the wrist. The NCS also showed an absence of sensory amplitude in both the left median and left ulnar nerves. The patient’s wrist drop recovered spontaneously at that time, and radial nerve conduction velocity was not measured. Doppler ultrasound revealed a physiological steal phenomenon, but it was not clinically significant. Radial arterial blood flow was also observed. Furthermore, his neurological deficits were clinically more severe than those caused by the ischemia. Consequently, we diagnosed the patient with IMN, rather than vascular steal syndrome, based on the presence of neurological symptoms and a radial pulse without necrosis of the skin or muscles.

Atherosclerosis of the opposite arm was so severe that sacrificing the existing AVF and creating a new AVF on the opposite arm was more likely to result in clinically significant vascular steal syndrome. Therefore, proximalization of the arterial inflow (PAI) surgery was performed to redistribute blood flow while maintaining the existing AVF (Fig. 2). After surgery, the patient’s left hand warmed, and his neurological symptoms gradually improved with consistent rehabilitation therapy.

Discussion

IMN was first described in 1983 and most frequently occurs in patients with diabetes and preexisting peripheral arterial occlusive disease [2]. Arteriovenous (AV) access in the upper arm is a known risk factor for IMN [3,4]. Its incidence is approximately 0.5% to 3.0%, and IMN can often be misdiagnosed or underdiagnosed [5]. Many causes of hand pain after AVF surgery, such as local nerve compression secondary to wound hematoma, carpal tunnel syndrome exacerbated by local swelling, IMN, and vascular steal syndrome, have been reported [5]. Therefore, a multidisciplinary approach is needed to uncover the cause of hand pain using various diagnostic methods such as vascular ultrasonography and electromyography.

Although many diagnostic methods can help confirm IMN, the key to diagnosing this condition is based on its clinical symptoms. Moreover, its pathogenesis is similar to that of ischemic steal syndrome. IMN results from a temporary blockage of blood flow to the nerve fibers of the forearm and hand, which is sufficient to damage these nerves but does not cause necrosis of other tissues. Therefore, IMN can be described as an ischemic steal phenomenon that only damages nerves [5]. Therefore, neurological examinations, including electrophysiological studies, are required to confirm the IMN diagnosis. Because the diagnosis of IMN is very difficult, every physician should pay attention to the patient’s symptoms and signs after vascular access surgery.

Furthermore, immediate surgical intervention is required to avoid permanent nerve damage and its subsequent effects. Closure of the AV access is recommended for IMN [6]; however, other treatment options, including AV access ligation, banding procedures, and PAI surgery, can also be considered [4]. In this case, sacrificing existing access and creating a new one on the other arm seemed difficult because of severe atherosclerosis. Therefore, PAI surgery was performed instead of AVF closure to redistribute blood flow and improve blood supply to the hand.

Article information

Conflicts of interest

Conceptualization, Formal analysis, Funding acquisition, Supervision, Validation: SHS; Data curation, Visualization: YHJ; Writing-original draft: DWK, YHJ; Writing-review & editing: DWK.

Acknowledgment

The authors would like to thank Yoo Mi Heo for creating the illustrations.

Funding

This work was supported by a clinical research grant from the Pusan National University Hospital in 2022.

Author contributions

Conceptualization, Formal analysis, Funding acquisition, Supervision, Validation: SHS

Data curation, Visualization: YHJ

Writing-original draft: DWK, YHJ

Writing-review & editing: DWK

Fig. 1.

The nerve conduction study shows reduced compound muscle action potential (CMAP) of the left ulnar nerve above the wrist and no CMAP of the left median nerve above the wrist. The patient’s left hand exhibits weakness in multiple intrinsic hand muscles innervated by the median and ulnar nerves. (A) Initial complaint of transient left wrist drop, which spontaneously recovered the next day. (B) Decreased grip strength due to ischemic monomelic neuropathy.

Fig. 2.

Ligation of the fistula and anastomosis between the axillary artery and forearm of the cephalic vein using a polytetrafluoroethylene (PTFE) graft is performed to improve blood flow into the distal artery. (A) The left brachiocephalic fistula operation is initially conducted. Square box indicates anastomosis site of fistula connecting brachial artery and cephalic vein. Arrows indicate the direction of blood flow. (B) Proximalization of the arterial inflow using a PTFE graft. Square boxes indicate anastomosis sites of graft. (1) Anastomosis of cephalic vein and graft; (2) anastomosis of axillary artery and graft. Arrows indicate the direction of blood flow.

References

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Figure & Data

References

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