Clinical manifestations of carpal tunnel syndrome (CTS) are known as subjective signs (paresthesia, proprioceptive alterations, paresis) and objective (alterations in sensitivity and motor function, positive Tinel and Phallen tests, and atrophy of the thenar eminence). Most of the patients are managed with medical or surgical treatment in relation to their clinical manifestations, the results of the electromyography in their progression. In some cases, presentation may be atypical and secondary atrophy may be present after severe compromise, which obliges the clinician to exclude other diagnoses.

We present the case of an 84-year-old woman with a history of controlled hypertension and 2 months with skin lesions on both hands, classified as a type of vasculitis associated with cyanosis on the first, second and third fingers, and severe pain that led to emergency hospitalization for suspected systemic vasculitis. Upon directed interrogation, there was no evidence of connective tissue disease or drug use. She received enalapril to treat high blood pressure. Physical examination highlighted periungual lesions, indicative of vasculitis, but their distribution was dermatomal, associated with severe hypoesthesia in the same territory and significant atrophy of the thenar region, bilaterally (Fig. 1). The rest of the examination was normal, in particular, no skin lesions at other sites were seen and her blood pressure was normal. Laboratory studies were performed: blood count, erythrocyte sedimentation rate and renal function as well as complete urine testing were normal, she had negative rheumatoid factor, negative antinuclear antibodies, ENA and negative C and P ANCA. The patient complained of abnormal sensitivity and nocturnal paresthesias and lack of strength in her hands for some time, so she had been seen by other physicians, leading to a diagnosis of CTS, undergoing an upper extremity electromyography a year earlier. This showed a severe entrapment of both median nerves at the carpal tunnel, with complete denervation of the thenar eminence. Ultrasonography was performed, showing the entrance to the tunnel at the pisiform, a right median nerve with a 17mm2 area (normal=±10mm2)1,2 (Fig. 2), with the central presence of a median artery remnant (Fig. 3). The left median nerve was also thickened, with an area at the pisiform level of 18mm2. Both nerves appeared trapped in the carpal tunnel in longitudinal sections (Fig. 4).

Fig. 1.

Right hand palm and a detail of the right index finger.

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Fig. 2.

Transverse image of the right median nerve at the entrance of the carpal tunnel, with measurement of the nerve area with an ellipse (0.17cm2), at the pisiform level P (B: large bone). (Image obtained with a General Electrics LOGIC e ultrasound, with a lineal 8–12mHz transducer, using a frequency of 12mHz and maximal enlargement.)

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Fig. 3.

Transversal image of the median nerve in the carpal tunnel: median artery remnant. (Image obtained with a General Electrics LOGIC e ultrasound, with a lineal 8–12mHz transducer, using power Doppler with a frequency of 5.0MHz, gain of 12, PRF DE 1.2hHz and a wall filter of 180Hz.)

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Fig. 4.

Longitudinal image of the right median nerve. (Image obtained with a General Electrics LOGIC e ultrasound, with a lineal 8–12mHz transducer, using a frequency of 12mHz.) B: large bone; N: median nerve; T: hand flexor tendons; *: compression zone.

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Skin lesions are localized on the median nerve territory because, as reported in the literature, in severe CTS there may be perivascular sympathetic nervous system compromise in that distribution.3–5 This patient also presented a remnant of the median artery, an uncommon anatomical variant6 generally associated to a bifid median nerve, leading to a greater repercussion on the compression of structures in the tunnel, affecting tissue vascularization even further. Thrombotic phenomena and occlusion of the remnant artery may be triggered for CTS.7,8 The case presented had a unilateral remnant artery; we may suppose that if it had occurred bilaterally it may have occluded and increased symptoms. Severe hypoesthesia adds the possibility of presenting associated traumatic lesions.9,10 It is important to perform the diagnosis because a surgical option, through the liberation of the nerve at the retinaculum, could revert the lesions, impeding the appearance of severe complications. This clinical presentation with atrophy in severe, long-term CTS is currently infrequent because most of the patients have rapid access to specialized care.

Faced with a patient with possible systemic vasculitis but with limited hands, the clinician must make a differential diagnosis with severe CTS and secondary atrophy because the treatment is very different and the use of steroids and immunosuppresants will not benefit these patients.