MRI findings of spinal accessory neuropathy.

AIM: To characterise the magnetic resonance imaging (MRI) appearance of patients with spinal accessory nerve (SAN) denervation. MATERIAL AND METHODS: Twelve patients who had SAN denervation on electromyography (EMG) were included. The sternocleidomastoid and trapezius muscles and the SAN were assessed using MRI. RESULTS: Trapezius muscle atrophy was seen in 11 (92%), and of those patients, T2/short tau inversion recovery (STIR) signal hyperintensity was also demonstrated in seven (58%). All three patients with prior neck surgery had scarring around the SAN, and one of these patients demonstrated a neuroma, which was confirmed surgically. CONCLUSION: Features of SAN neuropathy on MRI include atrophy and T2/STIR signal hyperintensity of the trapezius, and in patients who have had posterior triangle neck surgery, scarring may be seen around the nerve.

Imaging and electrodiagnostic work-up of acute adult brachial plexus injuries.

Imaging and electrodiagnostic studies form an essential part of the evaluation of the patient with traumatic brachial plexopathy, enabling clarification of surgical options, prognostication of outcome and formulation of postoperative management. The primary objective of imaging is to identify pre-ganglionic injury indicative of nerve root avulsion. The presence of one or more nerve root avulsion injuries is a critical factor in surgical decision-making and the prognosis of surgical reconstruction. CT myelography is the current imaging modality of choice for this purpose. Initial electrodiagnostic (EDX) testing is ideally performed no sooner than 4 weeks following injury unless otherwise clinically indicated. Follow-up testing can be helpful at approximately 6 week intervals. The sensory nerve amplitudes are the most important component of nerve conduction testing in distinguishing between pre- and post-ganglionic injuries. Electromyographic studies will also assist in the determination of a pre- from post-ganglionic injury, the level of plexus involvement and identify potential donor nerves that may be suitable for use as transfers.

Relationship between hip muscle imbalance and occurrence of low back pain in collegiate athletes: a prospective study.

OBJECTIVE: To assess whether athletes with strength imbalance of the hip musculature would be more likely to require treatment for low back pain (LBP) over the ensuing year. DESIGN: The study population included 163 National Collegiate Athletic Association Division I college athletes (100 males and 63 females) undergoing preparticipation sports physicals. Institutional review board approval was obtained to acquire and analyze hip muscle strength data. A commercially available dynamometer (Chatillon, Lexington, KY) incorporated into a specially designed anchoring station was used for testing the hip extensors and abductors. The maximum force generated for the hip abductors and extensors was used to calculate a percentage difference between the right and left hip extensors and abductors. Treatment of athletes by the athletic trainers for LBP unrelated to blunt trauma over the ensuing year was recorded. RESULTS: Of all athletes, 5 of 63 females and 8 of 100 males required treatment for LBP. Logistic regression analysis indicated that for female athletes, the percentage difference between the right and left hip extensors was predictive of whether treatment for LBP was required over the ensuing year (P = 0.05). There was no significant association noted for the percentage difference between the right and left hip abductors in females and for the percentage difference between both the right and left hip abductors and right and left hip extensors in males requiring treatment for LBP. CONCLUSIONS: These data support our results from our previous cohort study, adding validity to the concept of hip muscle imbalance being associated with LBP occurrence in female athletes. This research further supports the need for the assessment and treatment of hip muscle imbalance in individuals with LBP.

Effect of topical heat on electromyographic power density spectrum in subjects with myofascial pain and normal controls: a pilot study.

OBJECTIVE: To investigate the influence of superficial heat on the fatigue cascade of the upper trapezius muscle in subjects with myofascial pain and matched normal controls. DESIGN: In a prospective randomized block crossover pilot study, eight female subjects, ages 20-35 yr, with upper trapezius muscle trigger points and eight matched female control subjects without pain were studied. Subjects performed six 100-sec shoulder shrug contractions to fatigue, with subjects randomly chosen to receive heat during the first three or last three trials. The initial median frequency and the slope of the median frequency decline were calculated from the data. RESULTS: In the subjects with pain, the slope of the median frequency was elevated in ambient room temperature as compared with controls. There was no difference in slope of the median frequency under heated conditions. Heat application in controls before fatiguing exercise caused an increase in initial median frequency, whereas exercise before heat treatment resulted in a significantly lower initial median frequency. Subjects with myofascial pain had no significant change in initial median frequency. CONCLUSIONS: Heat seems to have a positive effect on muscle function in normal individuals when applied before exercise. Subjects with myofascial pain respond differently to exercise and heat challenge, which suggests a difference in their muscle physiology.

Burners and stingers.

The burner or stinger syndrome is one of the most common injuries in football and most likely represents an upper cervical root injury. Other sports reported include wrestling, hockey, basketball, boxing, and weight lifting. The athlete experiences radiating pain, numbness, or tingling down one upper limb, usually lasting less than 1 minute. Recurrences are common and can lead to permanent neurologic deficits. Burners are usually diagnosed and treated based on physical examination findings, but radiographs, MR imaging, and electrodiagnostic testing may help localize the precise level of injury, identify other associated pathology, and quantify neurologic injury. Management should include education on proper tackling techniques, restoration of neck motion, functional strengthening, and carefully fitted orthosis.

The relationship between lower extremity injury, low back pain, and hip muscle strength in male and female collegiate athletes.

OBJECTIVE: To determine the relationship of previous lower extremity (LE) injury and/or low back pain (LBP) on hip abduction and extension strength. DESIGN: Cohort study of college athletes at time of preparticipation screening physical. SETTING: An NCAA Division I college. PARTICIPANTS: Two hundred ten college athletes (140 males and 70 females) from an NCAA Division I school. MAIN OUTCOME MEASURES: Mean and maximal hip abduction and extension strengths were recorded using a specially designed dynamometer anchoring station. Previous injury to the LE or LBP in the past year was recorded via personal interview at the time of screening and verified by review of previous injury records. RESULTS: A significant difference in side-to-side symmetry of maximum hip extension strength was observed in female subjects who reported LE injury or LBP as compared to those who did not. Side-to-side difference in hip strength, however, did not differ between male athletes, regardless of reported LE injury or LBP status. CONCLUSION: Female athletes appear to have a differing response of the proximal hip musculature to LE injury or LBP, as compared with their male counterparts. Research is under way to further validate these findings. CLINICAL RELEVANCE: This study provides some reasoning to support the screening of hip strength during the preparticipation physical, as it may be important in the prevention of LE injury and LBP in collegiate athletes.

The reliability of monopolar and bipolar fine-wire electromyographic measurement of muscle fatigue.

Bipolar intramuscular wire electrodes and spectral analysis of the electromyographic signal have been used to measure fatigue in muscles that cannot be studied with surface electrodes. Intramuscular electrodes can detect a greater range of frequencies from muscle, obtain a less distorted signal, and are therefore felt to be more sensitive to detecting fatigue. To determine the reliability and sensitivity of electrode placement (with a fixed distance) for assessing muscle fatigue, we placed three intramuscular electrodes in and two surface electrodes on the biceps brachii of 30 healthy male subjects. With these electrodes, we devised eight configurations that were analyzed separately for reliability. Subjects performed four, 30-s isometric fatiguing contractions divided between two testing sessions. Mean and median frequency of the power density spectrum were plotted against time. Linear regression was performed to obtain slopes, which were used as indicators of fatigue. The bipolar surface electrode configuration displayed mean and median frequency intrasession and mean frequency intersession reliability for slope. All four bipolar fine-wire configurations had mean and median frequency intrasession reliability (P < or 0.05). Only three of the four bipolar fine-wire configurations approached mean frequency intersession reliability, and none fo the four displayed median frequency intersession reliability. the configuration with distal bipolar intramuscular electrodes placed 1 cm apart was the most reliable intramuscular technique. The bipolar fine-wire configuration studied showed a trend toward better reliability than monopolar fine-wire configurations. No intramuscular technique, however, was reliable enough for clinical use in the study of fatigue.

Low back pain in college athletes. A prospective study correlating lower extremity overuse or acquired ligamentous laxity with low back pain.

STUDY DESIGN: A prospective evaluation of the incidence of low back pain in college athletes was undertaken. OBJECTIVES: To evaluate prospectively leg length discrepancy, hip flexor tightness, and lower extremity acquired laxity or overuse as predictive factors for low back pain in college athletes. SUMMARY OF BACKGROUND DATA: A pilot study found an association between low back pain and the factors to be studied. Several allusions to the kinetic chain theory appear in the literature, but little prospective research has been done in examining the effects of lower extremity involvement on the back. METHODS: Two-hundred fifty-seven college athletes representing nine varsity sports were screened during a preseason sports physical examination. Measures of flexibility, ligamentous stability, leg length discrepancy, and overuse syndromes were recorded. Athletes were observed throughout the ensuing year for low back pain requiring treatment by the athletic trainer. Those athletes with low back pain as the result of direct trauma to the region were excluded from the data. RESULTS: Twenty-four athletes (9.3%) received treatment for low back pain. Thirteen of 87 women (15%) compared with 11 of 170 men (6%) required treatment for low back pain (P = 0.048). Of 57 athletes with lower extremity acquired laxity or overuse, low back pain developed in 14 (P < 0.001). CONCLUSIONS: Athletes with lower extremity acquired ligamentous laxity or overuse may be at risk for the development of noncontact low back pain during athletic competition. Female athletes with lower extremity involvement appeared to have a higher incidence of low back pain treatment compared with their male counterparts. Inflexibility of the lower extremities or leg length discrepancy were not associated with future low back pain treatment.

Effects of supplemental oxygen on forearm vasodilation in humans.

Supplemental O2 reduces cardiac output and raises systemic vascular resistance in congestive heart failure. In this study, 100% O2 was given to normal subjects and peak forearm flow was measured. In experiment 1, 100% O2 reduced blood flow and increased resistance after 10 min of forearm ischemia (flow 56.7 +/- 7.9 vs. 47.8 +/- 6.7 ml.min-1.100 ml-1; P < 0.02; vascular resistance 1.7 +/- 0.2 vs. 2.4 +/- 0.4 mmHg.min.100 ml.ml-1; P < 0.03). In experiment 2, lower body negative pressure (LBNP; -30 mmHg) and venous congestion (VC) simulated the high sympathetic tone and edema of congestive heart failure. Postischemic forearm flow and resistance were measured under four conditions: room air breathing (RA); LBNP+RA; RA+LBNP+VC; and 100% O2+LBNP+VC. LBNP and VC did not lower peak flow. However, O2 raised minimal resistance (2.3 +/- 0.4 RA; 2.8 +/- 0.5 O2+LBNP+VC, P < 0.04). When O2 alone (experiment 1) was compared with O2+LBNP+VC (experiment 2), no effect of LBNP+VC on peak flow or minimum resistance was noted, although the return rate of flow and resistance toward baseline was increased. O2 reduces peak forearm flow even in the presence of LBNP and VC.

Peripheral nerve injuries in the athlete.

Peripheral nerves are susceptible to injury in the athlete because of the excessive physiological demands that are made on both the neurological structures and the soft tissues that protect them. The common mechanisms of injury are compression, traction, ischaemia and laceration. Seddon's original classification system for nerve injuries based on neurophysiological changes is the most widely used. Grade 1 nerve injury is a neuropraxic condition, grade 2 is axonal degeneration and grade 3 is nerve transection. Peripheral nerve injuries are more common in the upper extremities than the lower extremities, tend to be sport specific, and often have a biomechanical component. While the more acute and catastrophic neurological injuries are usually obvious, many remain subclinical and are not recognised before neurological damage is permanent. Early detection allows initiation of a proper rehabilitation programme and modification of biomechanics before the nerve injury becomes irreversible. Recognition of nerve injuries requires an understanding of peripheral neuroanatomy, knowledge of common sites of nerve injury and an awareness of the types of peripheral nerve injuries that are common and unique to each sport. The electrodiagnostic exam, usually referred to as the 'EMG', consists of nerve conduction studies and the needle electrode examination. It is used to determine the site and degree of neurological injury and to predict outcome. It should be performed by a neurologist or physiatrist (physician specialising in physical medicine and rehabilitation), trained and skilled in this procedure. Timing is essential if the study is to provide maximal information. Findings such as decreased recruitment after injury and conduction block at the site of injury may be apparent immediately after injury but other findings such as abnormal spontaneous activity may take several weeks to develop. The electrodiagnostic test assists with both diagnosis of the injury and in predicting outcome. Proximal nerve injuries have a poorer prognosis for neurological recovery. The most common peripheral nerve injury in the athlete is the burner syndrome. Though primarily a football injury, burners have been reported in wrestling, hockey, basketball and weight-lifting as a result of acute head, neck and/or shoulder trauma. Most burners are self-limiting, but they occasionally produce permanent neurological deficits. The axillary nerve is commonly injured with shoulder dislocations but is also susceptible to injury by direct compression. The sciatic and common peroneal nerves can be injured by trauma. The suprascapular, musculocutaneous, ulnar, median and tibial nerves are susceptible to entrapment. The long thoracic and femoral nerves can be injured by severe traction.

Lower extremity injuries in college athletes: relation between ligamentous laxity and lower extremity muscle tightness.

OBJECTIVE: Two components of flexibility, muscle tightness, and ligamentous laxity in college athletes were studied to determine whether these factors were associated with the incidence of lower extremity injuries. DESIGN: Prospective cohort study. SETTING: College athletic department. PARTICIPANTS: 201 college athletes. OUTCOME MEASURES: College men and women athletes were tested for ligamentous laxity with the Beighton scale and for muscle tightness with a new scale based on the tightness of the iliopsoas, iliotibial band, hamstring, rectus femoris, and gastrocsoleus muscles. Lower extremity injuries incurred during practice and play were recorded during the following year. RESULTS: Of the 201 athletes tested, 71 sustained 115 injuries. For each additional point on the 9-point ligamentous laxity scale (9 = hyperlax), the risk of injury decreased 16%. For each additional point on the 10-point muscle-tightness scale (10 = all muscles tight), the risk of injury increased 23%. The two scores were moderately inversely correlated (Spearman's rho = -0.3; p < .001). Women had greater mean (+/- SD) laxity scores than men (3.3 +/- 2.2 vs. 1.8 +/- 2.0; p < .001) and lower mean overall muscle tightness scores (1.5 +/- 1.6 vs. 3.5 +/- 2.1; p < .001). Among Women athletes, the rate of lower extremity injury was unrelated to ligamentous laxity or to flexibility. Among men, lower extremity injuries were associated with lower ligamentous laxity scores (p = .008) and greater muscle tightness (p = .04). CONCLUSIONS: This study introduces a new scale for lower extremity muscle tightness. Tight ligaments and muscles are related to injury in men, but not women, college athletes. A preseason flexibility program may decrease injuries in college men athletes.

Spectral analysis during fatigue. Surface and fine wire electrode comparison.

Fine wire (FW) intramuscular electrodes and spectral analysis have not previously been used to quantify metabolic muscle fatigue in deep muscles not accessible with surface electrodes. This study compares initial median frequency (IMF) and decline in median frequency with fatigue (SLOPE) using surface and FW electrodes. Eighteen men performed isometric biceps contractions for 100 s. Electromyographic signals were collected using FW and surface electrodes. The recordings of SLOPE was greater with FW (-0.44 v -0.23 %IMF/s) and IMF was higher (195 v 69 Hz). Intrasession reliability for slope was better with FW electrode (intraclass correlation coefficient (ICC) = 0.74; P<0.0001) than with the surface electrode (ICC = 0.43; P = 0.006), but intersession reliability was best with the surface electrode (ICC = 0.50; P = 0.03). Spectral analysis using FW electrodes provides earlier detection of muscle fatigue and can be used in deep muscles, but the reliability must be improved before clinical application.

Hip pain: differential diagnosis.

This review discusses the many etiologies of hip pain and how to clinically evaluate. Both primary hip disorders and conditions that refer pain to the hip are included in the differential diagnosis. The key components to a history are reviewed with clinically relevant examples. A comprehensive physical exam is described that includes disease and injury-specific tests. Imaging studies and diagnostic tests available are outlined. Conditions of bursitis, snapping hip syndromes, myofascial pain, fibromyalgia, arthropathies, fractures, neurogenic pain, metabolic diseases, and neoplastic disorders will be discussed.

A model to predict canine pelvic limb musculoskeletal geometry.

We developed a model to predict the three-dimensional canine pelvic limb muscular geometry (i.e., all muscle moment arms during any instant in gait). Forty-one muscle origins and insertions, as well as external landmarks (to obtain anthropometric dimensions) were marked on both pelvic limbs of five dogs and digitized on biplanar radiographs. Reference frames in the pelvis, femur, and tibia established the three-dimensional coordinates of each origin, insertion, and landmark. A set of dimensionless 'scaled coordinates' was created by dividing the actual origin and insertion coordinates by selected anthropometric dimensions of each animal. Combining scaled coordinates from all ten limbs produced an averaged 'template' of scaled coordinates. To provide limited validation of the scaling procedure, we measured the anthropometric dimensions between externally palpable landmarks of two additional pelvic limbs. The anthropometric dimensions were multiplied by the averaged template coordinates to calculate two new sets of hindlimb muscle coordinates within the three bony reference frames. The two limbs then were dissected, muscle endpoints were marked, and biplanar radiographs of each of the limb segments were digitized. The actual coordinates so obtained were similar to those predicted by the template and anthropometric measures.