Biomedical subjects

Joon Shik Yoon

Publications and source records attributed to Joon Shik Yoon.

4 recordsLinked to original sources

PubMed2006

Cervical paraspinal spontaneous activity in asymptomatic subjects.

Paraspinal fibrillation potentials or positive sharp waves (PSWs) reportedly may be the only electrodiagnostic abnormality in patients with radiculopathies. However, spontaneous activity may be present in muscles of asymptomatic subjects. To determine whether abnormal spontaneous activity in the cervical paraspinal muscles is clinically relevant, we evaluated the prevalence of such activity in asymptomatic individuals and examined its relationship with age. Sixty-six asymptomatic subjects underwent a needle electromyographic examination of the paraspinal muscles bilaterally at the C5/6 and C6/7 levels. All of the recorded potentials were captured and their firing rates and waveforms were evaluated. The potentials were considered to be abnormal if reproducible trains of PSWs or fibrillation potentials were present. Eight of the 66 (12%) subjects showed PSWs, five bilaterally; none showed fibrillation potentials. A statistical analysis for the effect of age could not be performed due to the small sample size. Because electromyographic cervical paraspinal abnormalities can be found in asymptomatic subjects, caution should be exercised when attributing the etiology of neck pain to radiculopathy if the only electrodiagnostic findings are electromyographic cervical paraspinal abnormalities.

Action Potentials↗

PubMed2005

The feasibility of color Doppler ultrasonography for caudal epidural steroid injection.

Although it entails a radiation hazard risk, the use of fluoroscopy during caudal epidural steroid injection has increased to help place the medication more accurately and allowed physicians to maximize the procedure's therapeutic success rate. To investigate the feasibility of using real-time high resolution ultrasonography for guiding the epidural needle into the caudal epidural space and to confirm any vascular intake of medication, we performed color Doppler ultrasonography while medication was being injected into the caudal epidural space of 53 patients with low back pain and sciatica. We defined the injection as being successful if unidirectional flow (observed as one dominant color) of the solution was observed with color Doppler ultrasonography through the epidural space beneath the sacrococcygeal ligament, with no flows being observed in other directions (observed as multiple colors). The correct placement of the medication was then confirmed by fluoroscopy. In 52 of the 53 subjects, the medications were successfully injected into the caudal epidural space with ultrasonography assistance. In fluoroscopy, of these 52 patients, 50 revealed correct placement of the medicine into the epidural space. In conclusion, ultrasonography may be a reliable imaging modality for caudal epidural steroid injection, and its several advantages such as its convenience and the lack of a radiation hazard, make it preferable to fluoroscopy.

Adult↗

PubMed2005

Distance measure error induced by displacement of the ulnar nerve when the elbow is flexed.

OBJECTIVES: To determine the presence of ulnar nerve displacement at the elbow when it is flexed and to determine its effect on distance measurements using the conventional measurement method for nerve conduction studies (NCSs). DESIGN: Comparing the ultrasonography-assisted distance measurement method with the conventional measurement method. SETTING: An electrodiagnostic laboratory at a university hospital. PARTICIPANTS: Seventy-eight elbows of 39 healthy volunteers. INTERVENTIONS: We used high-resolution ultrasonography in real time. Based on sonographic searching, we marked 3 points on the skin through the course of the displaced ulnar nerve when the elbow is flexed: (1) point A, 7 cm above the elbow (from the midpoint between the medial epicondyle tip and olecranon in the postcondylar groove [point M]); (2) point B, 3 cm below the elbow; and (3) point C, the point closest to the medial epicondyle tip. MAIN OUTCOME MEASURES: Distance measurements between points A, B, and C were taken. These values were compared with measurements obtained through conventional measurement methods. RESULTS: Ulnar nerve displacement occurred in 24.3% (19/78) of the elbows; approximately 20.5% (16/78) were subluxation, and 3.8% (3/78) were dislocation. In the ulnar nerve displacement group, the distance between points A and C was 5.84+/-0.33 cm (range, 5.10-6.30 cm), and the distance between points B and C in the flexed position was 3.35+/-0.19 cm (range, 3.10-3.70 cm). When the conventional distance measurement was used, the ulnar nerve conduction velocity across the elbow was overestimated by approximately 5.33+/-2.29 m/s in the ulnar nerve displacement group. CONCLUSIONS: This distance measurement error may be responsible for the decreased sensitivity found in NCSs that test for ulnar neuropathy at the elbow. If the NCS results are normal in patients who have clear symptoms of ulnar neuropathy, the possibility of ulnar nerve displacement at the elbow should be considered, and further investigation with ultrasonography would be beneficial.

Adult↗

PubMed2002

Recovery of proximal and distal arm weakness in the ipsilateral upper limb after stroke.

Conservation of the ipsilateral upper limb function is important in stroke subjects with contralateral hemiplegia, because often it must serve as a compensatory tool for activities of daily livings (ADLs). However, the amount of functional loss and/or the recovery pattern of the ipsilateral upper limb are not well known. We plan to investigate how to measure the progress of the ipsilateral upper limb function after the onset of stroke. Once a week we used the Manual Function Test (MFT) to evaluate the ipsilateral upper limb weakness of 72 stroke subjects with contralateral hemiplegia until maximum recovery. Proximal and distal arm weaknesses in the ipsilateral upper limb were maximally recovered within one month following the onset of hemispheric stroke, but their weakness was not to be completely recovered. Also the amounts of their recoveries were different from each other. These results indicate that the ipsilateral upper limb weakness in stroke is not a temporary event and that motor function of the proximal and distal arm might be mediated by different neuronal circuits.

Activities of Daily Living↗