In addition to distal radius fractures, fractures and dislocations of the metacarpals and carpal bones can also lead to ACTS. Gong and Lu reviewed a series of 382 metacarpal fracture s and reported seven cases of ACTS in metacarpal shaft fractures and four cases of ACTS in fractures of the metacarpal base [11]. Kannan et al. describe a single case of volar fracture dislocation of the scaphoid leading to ACTS [12]. Olerud and Lonnquist report a single case of a patient with minimally displaced scaphoid and fifth metacarpal fractures that resulted in ACTS. During surgical release, a fracture hematoma was found in the carpal tunnel [13]. Others report cases of metacarpal or combined carpal and metacarpal fracture dislocations that resulted in ACTS necessitating surgical release [5, 14].

Carpal bone dislocations have also been associated with ACTS. Of these, perilunate fracture dislocations are perhaps the most common injury leading to ACTS. According to a prospective study of complex wrist injuries by Shivanna et al., the most common late presentation of perilunate dislocation was due to symptoms of ACTS. They reviewed 15 cases of carpal dislocations , and six had median nerve compressive symptoms. All six cases of median nerve compression were due to perilunate fracture dislocation, and all were delayed in presentation and underwent surgical fixation with carpal tunnel release [15]. The management for ACTS in perilunate dislocations is similar to that previously presented for distal radius fracture. Focus should be on first reducing the injury and monitoring for symptom improvement before performing carpal tunnel release in patients whose symptoms do not improve.

Given the frequency of median nerve compression in patients with perilunate fracture dislocations , some clinicians may elect to perform a carpal tunnel release at the time of surgical fixation even in patients without symptoms, particularly if a volar approach to the wrist is planned as part of the fixation. In a retrospective review of 32 patients, the authors noted that many patients who underwent carpal tunnel release at the time of fracture fixation had persistent symptoms even after a mean of 65 months of follow up. Six of the 32 patients had these persistent symptoms, and five of them had undergone release at the time of surgery. Three patients also developed delayed CTS. The reason for these continued symptoms is unclear, but the authors postulate that they are due to a chronic neural lesion rather than compression with the carpal tunnel [16]. In patients with symptoms of ACTS at the time of injury, carpal tunnel release should be performed at the time of surgery, and patients should be counseled that their symptoms might persist after surgery. The data is not clear whether or not release should be performed at the time of fixation of asymptomatic patients with perilunate or other carpal dislocations , and surgeons should continue to use their own clinical judgment.

Other reported causes of ACTS include acute tendon ruptures within or in proximity to the carpal tunnel. Flexor pollicis longus and palmaris longus tendon ruptures have both been reported to induce ACTS. Tendon ruptures may be caused acutely or may be the result of attritional changes following a prior fracture or dislocation [17, 18]. In these cases, patients with a prior fracture may develop ACTS years later when they suffer attritional tendon rupture. The cause of ACTS in this case is likely due to subsequent edema formation within the carpal tunnel. The treatment in these cases often includes excision of the tendon stump, tendon repair, or tendon transfer as well as a carpal tunnel release.

Burns and thermal injury can cause significant swelling, edema, and scar that may result in both acute and chronic presentations of carpal tunnel syndrome. In a review of seven patients treated for median neuropathy following flame burns that encompassed the hand and wrist, surgical release revealed excess fluid in the carpal tunnel occasionally requiring delayed closure [19]. Smaller surface burns to the hand can also lead to CTS. Bache and Taggart reported a case of partial thickness burns of the thumb and volar wrist with superficial burns to the dorsum of the hand that resulted in ACTS. Again, edema was seen within the carpal tunnel during surgical release [20].

Carpal tunnel syndrome can also be a late finding in burn injuries. In a retrospective review by Ferguson et al., the average time to release following burn injury was 249 days. The delayed presentation is likely due to ongoing scar formation in the region of the carpal tunnel. The overall incidence of CTS in upper extremity burns is estimated at 2–15%. Management of CTS in these cases is generally similar to other causes of chronic CTS [21].

Blunt trauma in the absence of fracture or dislocation has also been reported as a cause of acute presentation of carpal tunnel syndrome. This can occur in hyperextension injury in falls or direct blows to the hand or wrist that lead to intraneural or carpal tunnel hematoma or swelling. In 1949, Watson-Jones reported a case of ACTS in a cricket player who stopped a ball with his hand. Carpal tunnel release relieved the patient’s symptoms [22]. Faithfull and Wallace reported a case of median artery rupture from a fall that resulted in delayed presentation of CTS. Intraneural hematoma was found on surgical exploration, and neurolysis and carpal tunnel release also resolved the patient’s symptoms [23]. Treatment in these cases consists of conservative measures and observation for symptom improvement. If symptoms continue or worsen, urgent surgical decompression is warranted.

Other reported traumatic causes of CTS include snakebites, particularly by venomous snakes in which swelling and hemorrhage are common sequelae. In a review of 79 victims of snakebite in Turkey, only one patient developed ACTS, and in a similar review in Greece, three in 147 developed ACTS, making this a very uncommon scenario [24, 25]. Lazaro also reported a single case of ACTS following an insect bite [26]. While the common pathway appears to relate to edema formation related to venomous bite, these cases are rare, and thus treatment algorithms have not been established, and the need for carpal tunnel release is left to the surgeon’s discretion.