Author: Modern Weng, D.O.
Editor: Ashley Davidoff, M.D., Pierre d’Hemecourt, M.D.
CLINICAL BACKGROUND:
Chronic back pain in the young athlete can have a myriad of etiologies. However, a direct and targeted history and physical exam can generally establish a more precise list in the differential diagnosis. Chronic back pain in a young athlete with neurological deficit will tend to illicit more specific concerns broadly categorized as spinal nerve injuries secondary to vertebral fractures or impingement from a herniated nucleus pulposus.
Chronic back pain in a young athlete needs to be differentiated from back pain caused by a traumatic injury versus sudden onset of back pain without an inciting injury. In an adolescent aged athlete, sudden onset of back pain without an inciting injury should raise the concern of neoplastic and infectious etiologies. Therefore, an immediate MRI may be warranted.
IMAGING STRATAGIES:
WHAT STUDIES?
When a young athlete presents with persistent symptoms of chronic back pain with neurological deficits for 3-4 weeks, the initial study of choice is a MRI without contrast targeting the area of discomfort. There is no reason to obtain a plain film. Moreover, an MRI is a better study than a CT because it is better at showing any disc, nerve, and/or ligamentous injury.
WHY?
In a young amateur or professional athlete with chronic back pain and neurological deficits, the focus should be on treatment and when can the athlete return safely to sports? Therefore, an initial MRI study should be performed to evaluate for nucleus pulposus herniations and traumatic spondylothesis with spinal nerve compression. In addition, chronic back pain in a young athlete with neurological deficits may be secondary to an avulsion of the ring apophysis at its’ annular attachment. This hinged piece of fibrocartilage may irritate the spinal nerves as it projects into the canal, and thus, surgical resection is often necessary. The caveat is that this may be missed on MRI and detected only with CT scanning. (Peh)
WHEN?
Imaging should be performed at the time of presentation in order to expedite the diagnosis and treatment.
HOW TO ORDER?
When ordering either a plain film, CT, or MRI, it is important to reference the signs or symptoms as the clinical indication and not the diagnosis. For example, “sudden lower back pain with radiculopathy” is acceptable. However, “rule out disc herniation” would be inappropriate. Furthermore, evaluation of the back for musculoskeletal disease does not require contrast with an MRI, but does require contrast with a CT to investigate for an abcess or infection. When utilizing an MRI or CT for spondylolysis, “evaluate for sphondylolysis” must be conveyed in order to obtain the proper sequencing.
PATIENT PREPARATION:
For an MRI the patient should be cautioned that they will be required to lie still in a confined tunnel-like space for up to 30 minutes. The MRI can be very noisy and ear protection is provided. There is a call button provided to abort the procedure if problems arise.
CT scan—for patients receiving IV iodine contrast, allergies, medications, and renal function need to be identified before hand as the contrast may precipitate acute renal failure in at risk patients (i.e. diabetic on glucophage). For female patients, it is imperative to inquire about pregnancy before imaging.
CLINICAL RED FLAGS:
It is important to be aware of signs and symptoms of cauda equine syndrome when evaluating for back pain. Cauda equine syndrome is a surgical emergency caused by acute mechanical compression of nerves supplying the lower extremities, bowel, and bladder. Initial signs may be overflow incontinence, saddle anaesthesia, and loss of rectal tone. Therefore, a rectal exam and post void residuals should be obtained when suspicious. In the presence of these neurological deficits, the need to perform an urgent MRI is imperative.
Night time pain is also a potential harbinger of tumor and infection. The presence of fever, malaise, and elevated white blood cell count raises the question of an alternate differential diagnosis.
REFERENCES:
Peh WC, Griffith JF, Yip JK, Leong JC. Magnetic resonance imaging of the lumbar vertebral apophyseal ring fractures. Australas Radiol 1998; 42(1): 34-37