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THE ROLE OF INFRARED THERMAL IMAGING
(ITI)
IN MANAGEMENT OF NEUROPATHIC PAIN
Hooshang Hooshmand, M.D.
, Masood Hashmi, M.D. , and Eric M. Phillips
Neurological Associates Pain
Management Center
1255 37th Street, Suite B
Vero Beach, Florida, USA.
Abstract
The value of Infrared thermal imaging (ITI) is limited
to evaluation of neurovascular dysfunction. It provides useful diagnostic and
therapeutic information in the management of neuropathic pain[1].
Key Words: Infrared
thermal imaging, neuropathic pain, ITI in pain management.
Introduction
The nociceptive chronic pain is usually
due to involvement of large somesthetic (somatic) nerve fibres. Electromyography
(EMG) and nerve conduction velocity (NCV) tests are
usually the diagnostic tools for the study of somesthetic pain. In contrast,
these tests are normal in neuropathic pain because they can not detect changes
in the microscopic thermosensory neurovasculature. The diagnosis and management
of neuropathic pain requires neurovascular autonomic tests such as infrared
thermal imaging.
Methods
The role of ITI in pain
management was studied in 762 successive complex pain patients evaluated with
ITI. The results were compared with a meta analysis of medical
literature. A Bales Scientific Infrared Thermal Processor and an Agema (Flir)
Infrared Thermal Processor were utilized in this study. The patients were cooled
down in a 20-21ºC steady state room for 30
minutes of equilibration without clothing. No prior smoking for 90 minutes. A
standard sensitivity of 24-34ºC was done. If the areas were not properly
visualized the physician would adjust the sensitivity accordingly. Two
identically reproducible images recorded on laser disc were required.
Results
The study revealed the
importance of proper technique and proper clinical correlation. ITI is useful in
the study of complex neuropathic pain. It provides indispensable diagnostic and
therapeutic information. Both superficial and deep temperature changes influence
the ITI test. The skin is an almost perfect radiator of both deep and surface
heat. This radiator, has 98% emissive efficiency [2]. The ITI records
pathological temperatures at least as deep as 27 mm
(Fig 1) in the extremities, and even deeper in the breast [3-5].
Conclusion
ITI exclusively
provides diagnostic information in neuropathic pain. Such information cannot be
achieved by EMG or NCV. ITI is useless in diagnosis and management of cervical
and lumbar sprain. It can spare patients from unnecessary amputation, carpal
tunnel, temporomandibular joint, spinal disc surgeries and migraine. It is
helpful in differentiating cervicogenic headache from migraine-each requiring
opposite forms of treatment. In electrical injury ITI identifies points of
entrance and exit of electricity. This picture is pathognomonic and is
exclusively seen in electrical injury. ITI identifies hyperthermic foci of
permanent sympathetic system damage sparing the patient from further damage by
trauma of sympathetic nerve blocks.
Figure
1- A previously undiagnosed
right leg arteriovenous malformation over 27mm deep, complicated by Complex
regional pain syndrome. ITI identified the deep lesion and spared the patient
from the scheduled sympathectomy. Vascular surgery corrected the condition.
References
1. Hooshmand H: Is thermal
imaging of any use in pain management? Pain Digest. 1998; 8:166-170.
2.Elam R, Goodwin DN,
Lloyd-Williams K: Optical properties of human epidermis. Nature [Lond]. 1963;
198:1001.
3. Lawson RN:
Thermography- a new tool for the investigation of breast lesions. Can Med Assoc
J. 1957; 13:517- 524.
4.Thermography and its
clinical applications. Annals of the New York Academy of Science. 1964; 121:
304.
5. Ring EFJ: Progress
in the measurement of human body temperature. IEEE Engineering in Medicine and
Biology . July/August 1998; pp19-24.
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