Fascicular Involvement of the Median Nerve Trunk in the Upper Arm: Manifestation as Anterior Interosseous Nerve Syndrome With Unique Imaging Features

Selective fascicular involvement of the median nerve trunk above the elbow leading to anterior interosseous nerve (AIN) syndrome is a rare form of peripheral neuropathy. This condition has recently garnered increased attention within the medical community owing to advancements in imaging techniques and a growing number of reported cases. In this article, we explore the topographical anatomy of the median nerve trunk and the clinical features associated with AIN palsy. Our focus extends to unique manifestations captured through MRI and ultrasonography (US) studies, highlighting noteworthy findings, such as nerve fascicle swelling, incomplete constrictions, hourglass-like constrictions, and torsions, particularly in the posterior/posteromedial region of the median nerve. Surgical observations have further enhanced the understanding of this complex neuropathic condition. High-resolution MRI not only reveals denervation changes in the AIN and median nerve territories but also illuminates these alterations without the presence of compressing structures. The pivotal roles of high-resolution MRI and US in diagnosing this condition and guiding the formulation of an optimal treatment strategy are emphasized.

Factors Affecting the Occurrence of Late Median Nerve Neuropathy After Open Reduction and Volar Locking Plate Fixation of Distal Radius Fracture

It is well-known that late median nerve neuropathy can occur after open reduction and internal fixation (ORIF) of distal radius fracture (DRF). The current study investigated the predictive factors of late median nerve neuropathy after ORIF with a volar locking plate for DRF. The authors retrospectively reviewed 712 patients who underwent ORIF using a volar locking plate after DRF at 3 medical institutions between 2006 and 2017. Thirty-seven (5.2%) patients developed late median nerve neuropathy at a mean of 8.25±3.47 months (range, 3-19 months) after surgery. The radiographic data of 37 patients (group A) who had late median nerve neuropathy were compared with those of 148 patients (group B) who did not. Group A had a significantly higher proportion of type C3 fracture and Soong grade 2 than group B. Postoperative dorsal tilt in group A was greater than that in group B. On multivariable logistic regression analysis, the following predictive factors were associated with late median nerve neuropathy: increased postoperative dorsal tilt and Soong grade 2. The development of late median nerve neuropathy after ORIF using a volar locking plate for DRF was associated with increased postoperative dorsal tilt and the plate being placed distal to the volar rim. Physicians should consider the possibility of late median nerve neuropathy in patients with these factors during follow-up. [Orthopedics. 2021;44(3):e367-e372.].

Surgical Excision of a Thrombosed Persistent Median Artery Causing Carpal Tunnel-Like Symptoms: A Case Report

CASE

A 51-year-old man presented with pain and paresthesias in the median nerve distribution and a subjective loss of grip strength. Imaging revealed a thrombosed persistent median artery in the carpal tunnel abutting the median nerve. The thrombosed portion of the artery was surgically excised, and the patient experienced resolution of symptoms.

CONCLUSION

Persistent median artery thrombosis is rare and can cause carpal tunnel syndrome. Ultrasound is a useful tool for diagnosis and appropriate surgical planning. Although treatment with systemic anticoagulation is an option, surgical excision resulted in resolution of symptoms and an excellent short-term outcome.

Schwannoma of the median nerve mimicking carpal tunnel syndrome in a pregnant patient. Case report

In patients with symptoms of a peripheral neuropathy especially during pregnancy, use of imaging techniques such as Ultrasound (US) and Magnetic Resonance Imaging (MRI) may be essential for the diagnostic accomplishment. A 30-weekspregnant diabetic female attending US evaluation due to intermittent hand pain, numbness, and weakness bilaterally. Although, the US evaluation revealed the median nerve (MN) normal size, echogenicity and echo-texture within the right carpal tunnel; the US assessment applied proximally to the carpal tunnel, revealed a hypoechoic tumor-like mass and increased MN cross section area. In transverse view, the MN was detected as an eccentric, hypoechoic structure compressed by the aforementioned mass. A presence of MN schwannoma or neurofibroma was suspected. US has been proved to be extremely useful to determine location, extent as well as the type of nerve lesion.

Successful Treatment of Complex Regional Pain Syndrome with Pseudoaneurysm Excision and Median Nerve Neurolysis

BACKGROUND

Complex regional pain syndrome (CRPS), formerly referred to as reflex sympathetic dystrophy, is a pain syndrome characterized by severe pain, altered autonomic and motor function, and trophic changes. CRPS is usually associated with soft tissue injury or trauma. It has also been described as a rare complication of arterial access for angiography secondary to pseudoaneurysm formation.

CASE DESCRIPTION

A 73-year-old woman underwent catheterization of the left brachial artery for angiography of the celiac artery. The following day, the patient noticed numbness and severe pain in the median nerve distribution of the left upper extremity. Over the next 6 months, the patient developed CRPS in the left hand with pain and signs of autonomic dysfunction. Further work-up revealed the formation of a left brachial artery pseudoaneurysm with impingement on the median nerve. She underwent excision of the pseudoaneurysm with decompression and neurolysis of the left median nerve. Approximately 6 weeks after surgery, the patient had noticed significant improvement in autonomic symptoms.

CONCLUSIONS

This case involves a unique presentation of CRPS caused by brachial artery angiography and pseudoaneurysm formation. In addition, the case demonstrates the efficacy of pseudoaneurysm excision and median nerve neurolysis in the treatment of CRPS as a rare complication of arterial angiography.

Unusual median nerve schwannoma: a case presentation

Peripheral nerve sheath tumors are common soft tissue neoplasms and their characterization is often challenging. Although the surgical pathology defines some typical entities, some degree of controversy regarding the classification of these tumors still exists. Newer imagistic and histopathological techniques are crucial for their accurate diagnosis and grading. We present an unusual case of median nerve schwannoma in a young patient, discussing the clinical, surgical and pathological elements, including immunohistochemistry.

Long-term observation of auto-cell transplantation in non-human primate reveals safety and efficiency of bone marrow stromal cell-derived Schwann cells in peripheral nerve regeneration

Based on their differentiation ability, bone marrow stromal cells (MSCs) are a good source for cell therapy. Using a cynomolgus monkey peripheral nervous system injury model, we examined the safety and efficacy of Schwann cells induced from MSCs as a source for auto-cell transplantation therapy in nerve injury. Serial treatment of monkey MSCs with reducing agents and cytokines induced their differentiation into cells with Schwann cell properties at a very high ratio. Expression of Schwann cell markers was confirmed by both immunocytochemistry and reverse transcription-polymerase chain reaction. Induced Schwann cells were used for auto-cell transplantation into the median nerve and followed-up for 1year. No abnormalities were observed in general conditions. Ki67-immunostaining revealed no sign of massive proliferation inside the grafted tube. Furthermore, (18)F-fluorodeoxygluocose-positron emission tomography scanning demonstrated no abnormal accumulation of radioactivity except in regions with expected physiologic accumulation. Restoration of the transplanted nerve was corroborated by behavior analysis, electrophysiology and histological evaluation. Our results suggest that auto-cell transplantation therapy using MSC-derived Schwann cells is safe and effective for accelerating the regeneration of transected axons and for functional recovery of injured nerves. The practical advantages of MSCs are expected to make this system applicable for spinal cord injury and other neurotrauma or myelin disorders where the acceleration of regeneration is expected to enhance functional recovery.

Sonography versus nerve conduction studies in patients referred with a clinical diagnosis of carpal tunnel syndrome

PURPOSE

To compare the diagnostic value of high-resolution ultrasound (US) with nerve conduction studies (NCS) in patients with clinically defined carpal tunnel syndrome (CTS).

METHODS

A prospective study was conducted on 66 consecutive patients investigated for sensory hand symptoms. The gold standard was the clinical diagnosis of CTS.

RESULTS

NCS showed greater diagnostic sensitivity (82%) than US (62%) in supporting a diagnosis of CTS. With increasing neurophysiologic severity of median neuropathy, there was increasing convergence of the two test methods. Abnormal US as the only diagnostic supportive evidence of CTS was rare. However, the positive predictive value of US for CTS was 100%.

CONCLUSION

NCS show better sensitivity than US in supporting a diagnosis of CTS. However, because of its high positive predictive value, one may consider using US as a screening test, eliminating the need for NCS in the majority of clinical suspicion of CTS and reserving NCS for cases in which US is negative.

Sonographic findings of the median nerve and prevalence of carpal tunnel syndrome in patients with Parkinson's disease

PURPOSE

Parkinson's disease (PD) is a chronic progressive disorder which is characterized by rest tremor, akinesia or bradykinesia and rigidity. Carpal tunnel syndrome (CTS) is caused by compression of median nerve and can occur as a result of repetitive trauma. The aim of this study was to estimate the prevalence of CTS in PD and evaluate the median nerve sonographically.

MATERIALS AND METHODS

Fifty-three wrist of 29 patients with PD were included in the study according to Hoehn and Yahr (H&Y) clinical stage and divided into two groups. The first group consisted of 29 wrists of patients with mild PD (H&Y stage I-II). The second group consisted of 24 wrists of patients with severe PD (H&Y stage III-IV). Thirty-six wrists of 20 age-matched patients were used as control group. Both of the patients with PD and control group underwent sonography and electromyography (EMG). Axial sonograms of the median nerve were obtained at the level of distal radioulnar joint (level 1) and at the level of pisiform bone in the carpal tunnel (level 2). At each level, the cross-sectional area of the median nerve and flattening ratio were calculated.

RESULTS

There was no significant difference for all parameters, except one parameter, between the patients with PD and control group, and also among mild and severe groups of PD and control group (p>0.05). Interestingly, amplitude of median nerve in the second finger was significantly lower in PD patients than control group within normal limits (p=0.010). Of all wrists of PD patients, 13 (24.4%) have been diagnosed as CTS and 7 (19.4%) control wrists had CTS. Median nerve cross-sectional area of CTS patients were more than 10mm(2) in 6 (46%) wrists of PD patients but in only 1 (14%) control wrist at each level. Although it was not statistically significant, there was higher cross-sectional area at each level in patients with severe PD (level 1: 10.43+/-2.30 mm(2), level 2: 10.35+/-3.19 mm(2)) than patients with mild PD (level 1: 9.93+/-2.61 mm(2), level 2: 9.51+/-2.83 mm(2)) and control group (level 1: 9.69+/-3.19 mm(2), level 2: 9.07+/-3.61 mm(2)).

CONCLUSION

PD may pose a risk for the development of CTS due to the repetitive movement of tremor. Although sonography is not an ideal method of diagnosis for CTS, it may take our attention for indicating CTS in patients with PD especially in severe ones.

Posttraumatic pseudoaneurysm of the brachial artery and postsurgical retraction of median nerve: description of a case and ultrasonography findings

We present the case of a 25-year-old man who developed a brachial artery pseudoaneurysm and a subsequent haematoma after a penetrating injury with a window glass. A surgical excision of the pseudoaneurysm (anterior access) and a drainage of the haematoma were performed. After surgery, the patient developed a median nerve paresis, secondary to the postsurgical scar located in the elbow flexure. The diagnosis of these two entities was performed with ultrasound. Ultrasonography is an excellent imaging tool to make the diagnosis of pseudoaneurysms and nerve pathology, determining the presence, localization and extent of neural damage.

Role of sonography in the preoperative assessment of neurilemmoma

This case report illustrates the role of high-resolution sonography in the preoperative assessment of a neurilemmoma of the median nerve in the forearm. Sonography identified the 3-dimensional localization of the nerve tumor its origin from a nerve fascicle, and its relationship with noninvolved nerve fascicles, facilitating the surgeon's approach to preserve noninvolved fascicles.

Shoulder posture and median nerve sliding

BACKGROUND

Patients with upper limb pain often have a slumped sitting position and poor shoulder posture. Pain could be due to poor posture causing mechanical changes (stretch; local pressure) that in turn affect the function of major limb nerves (e.g. median nerve). This study examines (1) whether the individual components of slumped sitting (forward head position, trunk flexion and shoulder protraction) cause median nerve stretch and (2) whether shoulder protraction restricts normal nerve movements.

METHODS

Longitudinal nerve movement was measured using frame-by-frame cross-correlation analysis from high frequency ultrasound images during individual components of slumped sitting. The effects of protraction on nerve movement through the shoulder region were investigated by examining nerve movement in the arm in response to contralateral neck side flexion.

RESULTS

Neither moving the head forward or trunk flexion caused significant movement of the median nerve. In contrast, 4.3 mm of movement, adding 0.7% strain, occurred in the forearm during shoulder protraction. A delay in movement at the start of protraction and straightening of the nerve trunk provided evidence of unloading with the shoulder flexed and elbow extended and the scapulothoracic joint in neutral. There was a 60% reduction in nerve movement in the arm during contralateral neck side flexion when the shoulder was protracted compared to scapulothoracic neutral.

CONCLUSION

Slumped sitting is unlikely to increase nerve strain sufficient to cause changes to nerve function. However, shoulder protraction may place the median nerve at risk of injury, since nerve movement is reduced through the shoulder region when the shoulder is protracted and other joints are moved. Both altered nerve dynamics in response to moving other joints and local changes to blood supply may adversely affect nerve function and increase the risk of developing upper quadrant pain.

[Circumscribed median nerve compression caused by a leiomyoma. Preoperative localization with spiral CT]

Dysfunction of the median nerve is quite common and mostly observed related to carpal tunnel and pronator syndromes. We report a rare case of median nerve compression caused by a leiomyoma in the distal forearm. Spiral CT with MPR (multiplanar reconstruction) clearly located the lesion preoperatively.