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Musculoskeletal system
Published in A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha, Clark’s Procedures in Diagnostic Imaging: A System-Based Approach, 2020
A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha
The plantar aspect of the foot may be examined during the position for the medial and posterior aspects of the ankle as described above, or the subject may be seated on the couch with the legs extended so that the soles of the foot are vertical to the couch. The plantar fascia can be scanned in both long- and short-axis planes from its proximal origin on the medial calcaneal tubercle to its distal division where it merges into the soft tissues. To examine the interphalangeal or interdigital spaces, the probe should be placed longitudinally on the plantar aspect of the first interdigital space while the sonographer applies pressure on the dorsal surface. The transducer is moved laterally, with its centre at the level of the metatarsal heads, and the process repeated for the remaining interspaces and then again in the transverse plane. If a Morton’s neuroma is suspected, pressure can be applied to reproduce the patient’s symptoms. The intermetatarsal bursa lies on the dorsal aspect of the interdigital nerve, and care must be taken to correctly identify a neuroma and differentiate it from the bursa [39]. If there is suspected inflammatory arthritis, the metatarso-phalangeal joints should be examined in this position as well as dorsally for effusion, synovial hypertrophy, vacularity and bony erosions.
Designing for Foot and Ankle Anatomy
Published in Karen L. LaBat, Karen S. Ryan, Human Body, 2019
Outside mechanical forces can cause nerve damage. Fortunately, the locations of both sensory and motor nerves in the foot and ankle are relatively protected from footwear pressure. However, one type of compressive neuropathy (nerve damage caused by localized pressure) is a painful condition known as Morton’s neuroma (Young, Niedfeldt, Morris, & Eerkes, 2005). Seen predominately in women, it is attributed to damage of small sensory branches by the metatarsal heads and/or ligaments located in the interspaces between the toes. Although the precise cause is unclear, it is believed to stem from hyperextension of the toes in high-heeled shoes and/or from altered bony architecture from a bunion (Kimura, 2013, p. 778). Read more about bunions and other foot deformities later in this chapter. Katirji and Wilbourn (2005) state, “Typically, the [Morton’s neuroma] symptoms are relieved by non-weight bearing and by shoe removal” (p. 1507). They also state that nerve compression may be relieved with footwear modifications, including larger widths, low-heeled shoes, and limitation of toe extension.
Measurement of Electrical Potentials and Magnetic Fields from the Body Surface
Published in Robert B. Northrop, Non-Invasive Instrumentation and Measurement in Medical Diagnosis, 2017
ECoG is an NI, electrophysiological test of cochlear function that is used in the diagnosis of Ménière's disease (MD), endolymphatic hydrops, and in the differential diagnosis of eighth nerve neuroma (Ferraro 2000). The ECoG is a transient electrical potential produced by neurons in the cochlea in response to a repeated, audio click stimulus. The audio “click” can be a short, high-frequency, sinusoidal tone burst of about 5 ms in duration; different frequencies are used from 1 kHz or above. For example, a 5 ms burst at 2 kHz will contain 10 sound pressure cycles. Another way to produce clicks is to stimulate the transducer (usually a miniature headphone) with a narrow, DC pulse. The sound produced follows the headphone's electromechanical impulse response; it is a damped sinusoid at the resonant frequency of the headphone. If the pulse polarity is such that the initial displacement of the transducer's diaphragm is toward the head, a condensation or compression wave stimulus is said to be produced. A rarefaction stimulus occurs when the initial diaphragm movement is away from the head. The ECoG responses are slightly different for each type of stimulus, as shown in Figure 4.51 (Ferraro and Tibbils 1999). These averaged waveforms were from a patient with MD.
MR neurography of the brachial plexus in adult and pediatric age groups: evolution, recent advances, and future directions
Published in Expert Review of Medical Devices, 2020
Alexander T. Mazal, Ali Faramarzalian, Jonathan D. Samet, Kevin Gill, Jonathan Cheng, Avneesh Chhabra
MRN has emerged as a safe and useful modality in the neonatal population to characterize the location and grade of brachial plexus injury. Brachial plexus injuries occur in approximately 0.3 to 3.6 per 1,000 live births due to traction of the neck or upper extremity during passage through the birth canal [52–56]. In a study by Smith et al., MRN was found to correlate significantly with both physical exam and EMG findings in this population and correlated more strongly with physical exam findings than did EMG [41]* (reference 41 is believed to be of importance to readers, as it uniquely provides an objective comparison of MRN, EMG, and physical exam findings in pediatric age groups). In this study, all infants with brachial plexus injury were identified to have abnormal imaging findings on MRN. Abnormal imaging findings may include regions of abnormal T2 hyperintense signal of involved nerve segments, focal or diffuse enlargement of involved trunks or cords, visualization of end-bulb or neuroma in continuity at the injury site, and pseudomeningocele, etc. (Table 1). The utility of MRN in the setting of pediatric brachial plexus injury rests primarily in its ability to identify the minority (10%) of patients who ultimately will require surgery, most notably those suffering from avulsion or other pre-ganglionic injuries, which do not heal without microsurgical intervention [54,57].