الفهرس 
Aim of the workOnly 14 pages are availabe for public view
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Abstract
Magnetic resonance neurography is one of the most important and recent imaging modalities which has an exceeding role in diagnosis of carpal tunnel syndrome due to its effective ability in tracking the median nerve by means of complicated and highly sophisticated mathematical methods for detecting water (proton) anisotropic diffusion (DTI) within the nerve fibers when it faces a adequate magnetic field (1.5 T).
It can measure the different diffusion values such as fractional anisotropy (which decreases) and the ADC (which increases) in carpal tunnel syndrome. So the M.R. Neurography has a great role in following up carpal tunnel syndrome patients post operatively as it more accurate in assessing the respond of the nerve fibers after removal the cause of the compression.
However, MRN examination is relatively expensive, rather lengthy, and discomfortable because the patient position can have a major impact on the MRN studies, even minimal motions can have drastic impact on the image quality. This may limit the use of MRN examination for equivocal cases or if the cause of nerve entrapment poses a diagnostic dilemma.
High-resolution ultrasound examination is an effective, satisfactory modality in diagnosis of median nerve entrapment syndrome within the carpal tunnel. Its low cost, minimal time requirements and general availability favor its use as the initial study in evaluating the median nerve entrapment syndrome. Sonography has the additional advantage of being a dynamic study. Yet, it is still operator dependent.
Nerve cross sectional area in the carpal tunnel syndrome at the pisiform level is the most well correlated sonographic findings when compared to NC studies. Other variants in the carpal tunnel syndrome like the flattening ratio, the bowing of the flexor retinaculum have additional diagnostic capabilities.
Increased nerve size and decreased its echogenicity are indicative of nerve compression. High-resolution ultrasonography can provide data about possible aetiological factors when present.
Nerve conduction studies are still the gold standard modality for the diagnosis of carpal tunnel syndrome in clinical practice especially if the shift of conservative treatment to surgical release is needed.
However its relative invasive nature together with lack of anatomical and aetiological information may limit its use as a tool to monitor the progression of median nerve neuropathy through repeat studies and possibly reducing its role in screening patients suspected to have CTS.
Based on these results the following is recommended for evaluating the median nerve in carpal tunnel syndrome. In our algorithm if the patient is clinically suspected to have median nerve entrapment at the carpal tunnel, ultrasound examination is recommended as the first step in diagnosis after physician evaluation. Ultrasound examination yields three possible results:
• Normal carpal tunnel and abnormal median nerve within.
• Abnormal carpal tunnel and normal or abnormal median nerve within.
• Normal carpal tunnel and normal median nerve within.
In the first case, an abnormal median nerve is identified in normal carpal tunnel. The treatment can be based on ultrasound measurement of the median nerve combined with the clinical assessment. In mild cases, conservative therapy is indicated. But if the condition is severe, surgical intervention can be considered and ultrasound is then used to follow the patient’s progress after treatment.
In the second case, ultrasound imaging may detect disease localized to the carpal tunnel, such as tenosynovitis or ganglion. The median nerve may or may not demonstrate an abnormality associated with the carpal tunnel diseases. In this case the disease in the carpal tunnel is treated, and the patient is reevaluated with ultrasound. If the symptoms persist and the nerve is normal under ultrasound,combined MRN and NC studies are done to evaluate the nerve in its entirety.
In the third case, the patient has symptoms of carpal tunnel but demonstrates no discernable pathology in the osteofibrous carpal tunnel or the median nerve within. MRN examination is done for more detailed assessment of the median nerve. This is combined with nerve conduction studies for the evaluation of the nerves from the cervical roots to the hand to exclude intrinsic pathology of the nerve or a possible focal disease somewhere else along its course.
These options illustrate a change in the focus of median nerve entrapment at the carpal tunnel diagnosis from nerve conduction studies to ultrasound. With ultrasound, there are no needles piercing the muscle, and certainly no voltage is used to shock the patient.
Nerve conduction studies are not eliminated, but rather play an important and great role as problem-solving technique. Considering the difficulties many patients experience with nerve conduction studies, a combined approach using both ultrasound and MRN would yield high diagnostic efficacy while minimizing the patient discomfort.