Large Animal Neurology. Joe Mayhew
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thermographic patterns before and after exercise. Also, neurologic and disuse muscle atrophy have been associated with a lower overlying superficial temperature, when compared with the normal, opposite side. However, any such changes in skin temperature are very variable and not specific such that cutaneous thermography is not regarded as very useful for diagnosis and monitoring of spinal cord and nerve root diseases in humans178,179 and large animals. Its utility in cases of back pain in horses175,177, 180 is also dubious.
Because loss of sympathetic innervation in the horse causes demarcated cutaneous vasodilation and hyperhidrosis, thermography can be of great assistance in localizing any lesion affecting the sympathetic nervous system, particularly those involving peripheral nerves that contain sympathetic fibers. For example, the well‐known facial hyperthermia of Horner syndrome in the horse produces a characteristic, abnormal thermographic pattern.180–186
Scintigraphy
The use of scintigraphy in diagnostic neurology has been generally restricted to attempting to confirm cervical and thoracolumbar vertebral degenerative and inflammatory lesions,177,183, 185,187–191 in corroborating diagnoses of aorto–iliac–femoral arterial thrombosis192–194 and identifying the presence of portosystemic shunting195 as a cause of liver failure.
Ultrasonography
Soft tissue lesions that cause signs of neuromuscular disease and are accessible to ultrasound beams can be imaged and have included space‐occupying brain lesions,196,197 hydrocephalus,198 aortic–iliac–femoral thrombosis193,199–202 and musculotendinous lesions203,204 and muscle atrophy.205 This imaging modality can also be used to confirm the site of vertebral arthritis and discospondylitis177,187 and the presence of clinical or subclinical otitis media in calves.206 Recently, ultrasonographic examinations performed per rectum have been used to find abnormalities of lumbosacral and L5–6 intervertebral discs and foramina and associated lumbosacral nerves of horses.207,208 The technique also had favor in confirming the presence of enlarged vertebral articular processes seen radiographically and in guiding the administration of intra‐ and periarticular injections of medicaments at these sites,209–214 whether they are indicated or not.
Spinal endoscopy
The advent of microcameras has allowed the interesting but orphan technique of epidural and subarachnoid flexible endoscopy to be developed,215,216 but these techniques are really awaiting disorders for evaluation.217
Brain biopsy
Sounding heroic in large animal neurology circles, brain biopsy is actually a relatively straightforward surgical exercise in human and small animal neurology,218,219 and the goal of obtaining a histologic diagnosis is laudable. But of course the damage caused in attaining a biopsy for histologic evaluation must be kept minimal, and clinically vital regions of the brain must be avoided. However, with training,220 the application of new imaging techniques with neuronavigational guidance procedures will allow diagnostic brain biopsies to be obtained efficiently.221
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