A 65-year-old male presented with acute history of loss of strength in the right hand and paresthesia in the medial two fingers. Healso had partial clawing of the fourth and fifth fingers (Fig.1). Nerve conduction velocity test (NCV) revealed sensorimotor axonal affection of right ulnar nerve. There was no history of trauma. He was doing fitness for 2 months.
On High-Resolution ultrasonography (USG), a well-defined, thin-walled anechoic cystic lesion in the proximal Guyon’s canal was seen. A small neck was seen extending medially from this lesion towards the pisotriquetral joint. Lesion was displacing and compressing the ulnar nerve within Guyon’s canal. Approximate size of cyst was18 x 8 mm (Fig.2a,2b,2c). On colour doppler, no vascularity was seen.
Based on these imaging findings, the diagnosis of ganglion cyst was made. At surgery, this diagnosis was confirmed. The lesion was dissected from Guyon’s canal and excised (Fig.3). Histopathology confirmed the diagnosis of a ganglion cyst. Post-operatively, there was immediate improvement in symptoms.
Background
Ulnar nerve compression in Guyon's canal is a rare pathologic condition.[1]Some causes of ulnar nerve compression at Guyon’s canal include lipoma, ganglion cyst, ulnar artery aneurysm, hamate hook fracture, radius fracture, pisiform fracture, other wrist bone fracture, chronic repetitivetrauma to wrist as in handlebar palsy in cyclists. [2]
Guyon’s canal is a closed anatomical space with fibro-osseous boundaries along the volar ulnar aspect of wrist which contains the ulnar nerve and vessels.[3]
Ganglion cysts are benign cystic masses that usually occur in association of musculoskeletal structures. 60-70 % of ganglion cysts are found around wrist and communicate with the joint via a pedicle.[4]
Clinical Perspective
Ganglion cysts are usually asymptomatic; however, symptoms can be developed due to mass effect over adjoining structures like nerve compression.[4]Many patients report that the mass fluctuates in size, growing after periods of increased activity and shrinking with inactivity.[5]
Clinical symptoms of compressive neuropathy are usually insidious in onset. Our Patient had a relative rapid onset of symptoms. This could be explained by acute protrusion or growth of the ganglion cyst in Guyon’s canal which can be triggered by recent unaccustomedwrist movements. Compression at Guyon’s canal is divided into three types according to Gross-Gelberman zone theory.[6] Compression of ulnar nerve in proximal portion leading to sensory and motor deficit (Type I); compression of the deep branch in distal portion resulting motor changes alone (type II); and compression of the superficial branch alone causing sensory deficit without motor impairment (type III). Presence of ganglion cyst in proximal portion describes the sensorimotor affection of ulnar nerve in our case.[2]
Imaging Perspective
Typical USG findings of ganglion cyst include an anechoic or hypoechoic well-defined mass, oval or round in shape. Often an anechoic neck is seen extending to the adjoining joint.[7] On MRIit appears hyperintense on T2 and usually hypointense on T1 but may be seen hyperintense due to high proteinaceous contents/haemorrhage.
Take-Home Message
Acute ulnar compressive neuropathy by a ganglion cyst in Guyon's canal is rare. However, clinicians should consider the ganglion cyst in Guyon's canal as a possible underlying cause of compression, Because early decompression/excision of ganglion cyst is an important step toward a complete recovery.USG is the screening modality of choice in case of peripheral neuropathy, even in some cases it may be diagnostic. One advantage of ultrasound is guided aspiration which can confirm the cystic nature of swelling.
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Acute compressive ulnar neuropathy caused by Guyon’s canal ganglia.
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According to the provided ultrasound and surgical images, a cystic lesion can be observed near the ulnar side (Guyon canal area) of the right wrist. Internally, it appears relatively hypoechoic or anechoic, with a clear boundary from the surrounding tissues. This lesion is adjacent to the course of the ulnar nerve, suggesting compression of the ulnar nerve. The patient’s physical examination shows a partial claw deformity of the 4th and 5th fingers on the right hand, along with sensory abnormalities on the ulnar side of the hand, consistent with ulnar nerve compression. The imaging characteristics are as follows:
Based on the clinical presentation (sensory and motor disturbances of the 4th and 5th fingers) and imaging findings (a cystic lesion compressing the ulnar nerve), the main diagnostic considerations include:
Given the sudden onset of symptoms and the imaging characteristics, the most likely diagnosis is a ganglion cyst leading to compression of the ulnar nerve.
Considering the 65-year-old male patient, with no obvious history of trauma, who presented with ulnar-sided weakness and sensory disturbances in a short period, and the ultrasound and surgical findings confirming a cyst within the Guyon canal, the final diagnosis is:
“Right ulnar nerve compression in the Guyon canal (caused by a ganglion cyst)”
If further clarification of the lesion is necessary, MRI evaluation or aspiration/biopsy can be conducted. However, at present, the ultrasound findings and clinical symptoms are highly consistent.
Rehabilitation should follow the principle of gradual progression and individualization, utilizing the FITT-VP framework (Frequency, Intensity, Time, Type, Progression, and Individualization):
Throughout the rehabilitation process, closely monitor the patient’s pain, swelling, and neurological symptoms. If there is any exacerbation, return for re-evaluation or adjust the plan promptly.
This report provides only a reference medical analysis and does not replace an in-person consultation or professional medical advice. Specific treatment and rehabilitation plans should be determined by qualified medical professionals in accordance with the patient’s individual condition.
Acute compressive ulnar neuropathy caused by Guyon’s canal ganglia.
