Thenar hypoplasia with associated radiologic abnormalities

Coexistence of anomalous muscle, persistent median artery, bifid median nerve causing carpal tunnel syndrome: A case report and literature review

Carpal tunnel syndrome (CTS) is an upper extremity median nerve entrapment disorder that is rare in children and adolescents. Anatomical variations of the wrist, such as anomalous muscles, persistent median artery (PMA), and bifid median nerves (BMN), are rare etiology of CTS. Coexistence of all three variants combined with CTS in adolescents has been rarely reported. Case description: A 16-year-old right-hand dominant male presented to our clinic with several years of bilateral thenar muscle atrophy and weakness but no paresthesia or pain in his both hands. Ultrasonography showed that the right median nerve become significantly thinner, and the left median nerve was split into two branches by PMA. Magnetic resonance imaging (MRI) revealed that anomalous muscles in the bilateral wrist extending to the carpal tunnel, causing compression of the median nerve. Considering the possibility of CTS clinically, the patient underwent bilateral open carpal tunnel release without resection of anomalous muscles and PMA. The patient has no discomfort after 2 years. This suggests that anatomical variations of the carpal tunnel may contribute to CTS, which can be confirmed by preoperative ultrasonography and MRI, and the possibility of carpal tunnel anatomical variations should be considered when CTS occurs in adolescents. Open carpal tunnel release is an effective treatment for juvenile CTS without the need to resect abnormal muscle and PMA during the operation.

Ultrasonography in patients with congenital thenar hypoplasia (Cavanagh syndrome) and co-morbid carpal tunnel syndrome

Objective

Patients with congenital thenar hypoplasia (Cavanagh syndrome) may undergo surgical intervention with a mistaken diagnosis of severe carpal tunnel syndrome. Conversely, patients with Cavanagh syndrome can develop co-morbid median nerve entrapment at the carpal tunnel later in life and may go untreated. This study is aimed at evaluating the role of ultrasonography in confirming/ruling out median nerve entrapment at the carpal tunnel in patients with Cavanagh syndrome.

Methods

6 patients with Cavanagh syndrome were identified during a 10-year period from among patients referred for preoperative electrodiagnostic confirmation of carpal tunnel syndrome. All patients underwent ultrasound imaging as well as electrodiagnostic studies including motor conduction study of the median nerve with recording electrodes over the lumbrical muscles.

Results

Age range of patients was 39-76. The right hand was affected in 5 and left hand in 1 patient. Electrodiagnostic studies (EDX) confirmed carpal tunnel syndrome in 4 of the 6 patients. In one patient the nerve conduction studies were non-diagnostic due to absence of compound muscle action potential (CMAP) over the thenar, and the 2nd lumbrical muscles and absent sensory nerve action potentials (SNAP). Ultrasound images confirmed entrapment of median nerve at the carpal tunnel in all 5 patients. The sixth patient was mistakenly diagnosed with severe carpal tunnel syndrome by the referring physician, based on the thenar atrophy; the median nerve was normal in both ultrasound and electrodiagnostic studies.

Conclusion

Ultrasound was useful for confirming/ruling out comorbid carpal tunnel syndrome in all 6 patients with Cavanagh syndrome.

Significance

Ultrasound complements electrodiagnostic study findings in patients with congenital thenar hypoplasia and comorbid carpal tunnel syndrome. It is even more valuable when EDX findings are non-diagnostic due to absent CMAP and SNAP.

Congenital Thenar Hypoplasia with Absent Radial Artery: A Case Report

The thenar eminence is made up of the intrinsic muscles of the hand that are responsible for complex movement and finite motor functions of the hand. The wasting of these muscles can be associated with various clinical conditions. Cavanagh syndrome is a rare, isolated congenital thenar hypoplasia with characteristic clinical, radiological, and electrophysiological features. Congenital absence of the radial artery is a rare anatomic variant. We report a case of a boy with isolated right-sided congenital thenar hypoplasia meeting the clinical and radiological characteristics of Cavanagh syndrome with concurrent absence of the right radial artery.

Carpal tunnel syndrome in children

Carpal tunnel syndrome rarely occurs in children. We retrospectively analyzed clinical data of 11 patients aged 5-17 diagnosed with carpal tunnel syndrome at a single pediatric neuromuscular center. Nerve conduction studies were performed according to the American Association of Electrodiagnostic Medicine recommendations. Additional imaging tests of the wrist were performed in 10 patients. In our group of 11 children, carpal tunnel syndrome was idiopathic in only 1 case. In the remaining subjects, it was secondary to congenital bone anomaly (6), hypothyroidism (2), or myopathic contractures (1). In 1 case, metabolic workup revealed an underlying mucopolysaccharidosis. Our results confirm that idiopathic carpal tunnel syndrome is rare in children. Hand clumsiness and thenar hypoplasia rather than sensory complaints are the presenting symptoms. Whenever carpal tunnel syndrome is diagnosed in a child, a thorough differential diagnosis should be made because of the secondary nature of this disease in most pediatric patients.

Bipolar affective disorder associated with thenar hypoplasia: is lithium safe?

Thenar hypoplasia has been described to occur as a part of radial longitudinal deficiency syndromes and occasionally related to Holt-Oram syndrome in which both cardiac and skeletal abnormalities co-occur. We describe a case with bilateral thenar hypoplasia, which resembles a milder variety of Holt-Oram syndrome, who developed bradycardia after exposure to lithium at therapeutic doses.

Congenital thenar hypoplasia with absent radial artery--a case report

Cavanagh syndrome is a rare, isolated congenital thenar hypoplasia with characteristic clinical, radiological and electrophysiological features. It has never been reported to occur in association with absent radial artery. We report the case of a boy with left sided congenital thenar hypoplasia fulfilling the characteristic clinical, radiological and electrophysiological features of Cavanagh syndrome, associated with congenital absence of left radial artery. We also discuss the possible underlying aetiopathology of Cavanagh syndrome.

Cavanagh's syndrome (congenital thenar hypoplasia)

Thenar hypoplasia can be an isolated defect, as in Cavanagh's syndrome, can be present with cardiac (Holt-Oram syndrome) or eye (Okihiro's syndrome) disorders, or can be associated with hand anomaly, as in Haas's malformation. Vascular abnormality may be associated with thenar hypoplasia, which has been demonstrated in Okihiro's syndrome. Cavanagh's syndrome is a rare anomaly of the upper extremities that presents with unilateral or bilateral hypoplasia of the thenar eminence. Typical clinical, radiographic, and electrophysiologic findings emphasize the diagnosis. Differentiation from carpal tunnel syndrome is important to prevent unnecessary intervention. Electrophysiologic and radiographic findings are necessary tools for the physician to establish a correct diagnosis and make an appropriate referral. Because of its rarity, we present the case of an 8-year-old girl with this syndrome.

Thenar hypoplasia in Klippel-Feil syndrome due to aberrant radial artery

A 10-year-old boy with Klippel-Feil syndrome had progressive atrophy of the left thenar eminence and absence of left radial pulse. Neurophysiologic studies and angiography were normal. However, duplex sonography over the wrists revealed an aberrant left radial artery. We speculate that the thenar atrophy in this patient is congenital, which may be due to the anomaly of the left radial artery, and is further compromised by vascular compression in the thoracic outlet.

Pediatric median mononeuropathies: a clinical and electromyographic study

Seventeen children, 6 girls and 11 boys, aged 5-17 years with pediatric median mononeuropathies (PMM) were identified among 1809 who had EMGs primarily in the electromyographic laboratory at The Children's Hospital, Boston, between 1979 and 1993. Electromyography documented the PMM to be at the wrist in 7 children, including 3 children with idiopathic carpal tunnel syndrome (CTS)--1 whose symptoms were accentuated by skiing--2 with a systemic illness (mucolipidosis III and scleroderma), and in 1 child each the distal PMM was secondary to a cast or laceration. A proximal PMM was identified in 10 children, including 8 with trauma, 1 with an osteoid osteoma, and 1 with juvenile cutaneous mucinosis. Five children (3 with CTS and 1 each with mucolipidosis III and juvenile cutaneous mucinosis) had bilateral disease. The localization (59% proximal) and cause of these PMMs differed greatly from our experience with adult median neuropathies.

Unilateral thenar hypoplasia

This report documents a patient with unilateral hypoplasia of the thenar eminence. The clinical, electrodiagnostic, and radiological findings indicated a developmental abnormality which must be considered in the differential diagnosis of carpal tunnel syndrome.