Acute Ulnar Neurapraxia and Carpal Tunnel Syndrome in the Context of a Distal Radius Fracture

Distal radius fractures are among the most common fractures that present to emergency departments.^1,2 The mechanism of injury for these fractures is typically a fall on an outstretched hand. Patients commonly develop carpal tunnel syndrome (CTS) after a distal radius fracture.³ CTS is the most common compressive neuropathy of the upper extremity and inflammation around the median nerve causes progressively debilitating symptoms such as dysesthesia, anesthesia, and wrist pain.⁴ Although injury to the ulnar nerve is the most common upper extremity peripheral nerve injury requiring hospitalization, it is less common for a fracture of the distal radius to be the principal cause of ulnar neuropathy.⁵ The following is a unique case of both acute ulnar neurapraxia and CTS after distal radius fracture. 

A 33-year-old, right-hand dominant, male patient presented to the emergency department for evaluation of left wrist pain with persistent numbness and tingling after falling on an outstretched arm while participating in recreational sport activities 2 days prior. The patient reported to be in good health and denied any medical conditions or tobacco use. On physical examination, limited passive and active range of motion was noted due to edema and a closed skin deformity of the left wrist. Severe ulnar neurapraxia was observed on initial examination, along with the loss of sensation in the left median nerve distribution. The patient maintained good perfusion. 

Standard 3-view radiographs were obtained, which demonstrated a left dorsally displaced extraarticular fracture of the distal radius (Figure 1). A reduction under traction and hematoma block was performed to obtain acceptable alignment of the distal radius fracture. The patient’s neurovascular examination remained unchanged throughout the procedure, as well as immediately and 2 hours after reduction. Persistent ulnar palsy, including considerable weakness in the intrinsic muscles of the digits, remained present on the left. 

Based on clinical and radiographic findings, the diagnosis of a left distal radius fracture with median nerve injury consistent with CTS and severe ulnar nerve palsy was concluded. An open reduction and internal fixation of the left distal radius fracture with release of the left Guyon’s canal as well as the carpal tunnel were performed.

Using the transflexor carpi radialis (FCR) approach to the radius, the fracture was provisionally fixed with a 0.062 Kirschner wire (K-wire). A distal DVR plate (Acumed, LLC) was placed along with two 0.54 K-wires, and reduction was confirmed with intraoperative fluoroscopy. The distal holes were filled, and proximal screws were placed using intraoperative fluoroscopy throughout the procedure to confirm screw position and length.

The Brunner’s type incision over Guyon’s canal was then used to completely release the antebrachial fascia proximally and the entire Guyon’s canal distally. During this part of the procedure, a significant hematoma was noted around an edematous ulnar nerve. The carpal tunnel was then released using the Brunner incision by dissecting over the fascial plane radially. Similar to the findings within Guyon’s canal, a significant hematoma was also noted within the carpal tunnel around the median nerve as well as in the intrasynovial space surrounding the flexor tendons (Figure 2).

The patient tolerated the procedure well with no perioperative complications and was discharged the same day. Repeat radiographs obtained during the first postoperative clinic appointment several days later showed stable reduction with maintained alignment without hardware failure (Figure 3). Subjectively, the patient emphasized feeling great relief postoperatively with respect to markedly decreased numbness and tingling along the ulnar nerve distribution and reported slight improvement in sensation along the median and ulnar nerve distributions. Hand-specific occupational therapy was begun on postoperative day 2 with the assistance of a specialized therapist. The patient continues to improve and follows up regularly in clinic. 

The presentation and management of ulnar nerve injuries are diverse and complex.⁶ Most ulnar compression syndromes are sequelae of ganglia originating from the carpal, midcarpal, and ulnocarpal joints.^7-9 When caused by trauma, ulnar compression is often the result of repetitive compressive or vibration forces, rather than distal radius fractures.^{7, 10} Given the patient’s sensorimotor deficits presenting directly after trauma to the distal radius, the fracture and subsequent hematoma burden were the inciting events leading to both the ulnar neurapraxia as well as the CTS symptoms. The physical examination findings in the patient were consistent with a low ulnar nerve injury given the loss of sensation and motor deficits of the interosseus muscles.¹¹ The operative technique of Guyon’s canal release to relieve symptoms of ulnar nerve compression worked well for this patient. Additionally, release of the carpal tunnel provided great relief of the patient’s dysesthesias and sensory deficits in the distribution of the median nerve. 

Only one prior publication has reported ulnar nerve compression symptoms after distal radius fracture, but treatment was done by shortening the osteotomy of the ulna bone rather than Guyon’s canal release.¹² To the authors’ knowledge, this is the first case report describing concomitant acute presentation 

of CTS and ulnar nerve entrapment treated with Guyon’s canal release directly due to compression from hematoma as a result of a distal radius fracture. 

Distal radius fractures, ulnar nerve compression, and median neuropathy are all common pathologies causing patients to present to emergency departments and hand clinics.¹ Rarely do all 3 insults occur concomitantly. Emergency medicine providers are well versed in the care of distal radius fractures and should understand that sensorimotor deficits in the hand likely warrant consultation by a hand or plastic surgeon. Similarly, hand surgeons should be aware of nerve injuries that, although rare, may occur due to distal radius fractures, and understand indications and approaches to urgent compartment release. 

Affliations: ^aDivision of Plastic and Reconstructive Surgery, Rush University Medical Center, Chicago, IL 60607, USA. ^bDivision of Plastic and Reconstructive Surgery, Cook County Health, Chicago, IL 60607, USA.

Correspondence: Charalampos Siotos, Division of Plastic and Reconstructive Surgery, Rush University Medical Center, Professional Building, Suite 425, 1725 W Harrison St, Chicago, IL 60612; Charalampos_siotos@rush.edu.

Disclosure: The authors disclose no financial or other conflicts of interest.