The diagnosis and management of concussion is a topic of interest in the sports medicine community. Much is being published about this subject, and one can generally infer that awareness of this condition is increasing. Despite this, there is limited information about the diagnosis and management of concussion in atheletes with underlying central nervous system conditions. The presentation of concussion and worsening of these underlying conditions could have similar presentations, making the correct diagnosis difficult, but essential.
A 15-year-old male defensive lineman with Chiari I malformation and previous decompressive surgery presented to clinic for evaluation of altered mental status and progressive neurologic symptoms. His symptoms started suddenly during a high school football game 3 days earlier. He did not remember any specific collision, impact, tackle, or other injury that could have caused his symptoms. His teammates noticed that he was not in his normal three-point stance and seemed dazed. This prompted his athletic trainer to evaluate him. During the examination on the sideline, the athlete reported that he had a headache, photophobia, phonophobia, dizziness, loss of balance, and nausea without vomiting. He was removed from the game, but worsening photophobia, dizziness, and nausea developed over the course of the next several days. He denied any history of motion sickness, mood disorder, or attention deficit hyperactivity disorder. His physical examination on presentation to clinic was significant for horizontal nystagmus, severe dysdiadochokinesia with rapid alternating movements, severe dysmetria with finger-to-nose-testing, a positive Romberg test, and inability to perform a tandem gait when prompted.
Due to the severe nature of his symptoms and physical examination findings, he was sent for emergency magnetic resonance imaging (MRI) of his brain. The MRI showed evidence of a C1 laminectomy and extension of the cerebellar tonsils 1.7 cm below the foramen magnum (Figure 1), which was unchanged from imaging 3 years prior to this event (Figure 2). Three days after his initial clinic visit, he was examined again by his sports medicine physician. He had significant improvement in neurologic function and was back to his baseline neurologic status. Because his MRI showed no intracranial pathology or change in his Chiari I malformation, his neurologic symptoms had resolved, and his SCAT 3 testing was back to baseline, he was diagnosed as having sports-related concussion. He was started on a return to play protocol and ultimately returned to participate in his team’s next football game.
Magnetic resonance imaging showed evidence of a C1 laminectomy and extension of the cerebellar tonsils 1.7 cm below the foramen magnum.
Comparison magnetic resonance imaging obtained prior to current injury.
Chiari I malformations, in which the cerebellar tonsils descend into the upper cervical spinal canal through the foramen magnum, are a fairly common finding on MRI. The distance at which the tonsillar descent is described to be pathologic is 3 to 5 mm below the level of the foramen magnum.1 One study noted an incidence of 0.56% among a population of more than 12,000 patients,2 whereas another study of more than 22,000 patients found a prevalence of 0.77%.1 There is a difference of opinion regarding clearance for athletic participation in patients with this malformation. Older studies have considered Chiari I malformation a contraindication to participate in contact sports; however, newer studies are recommending that medical clearance for participation be conducted on a case-by-case basis3–6 (Table 1).
Clearance for Contact Sport Recommendations in Athletes With Chiari I Malformation
This case is unique in that it required evaluating a patient with a known Chiari I malformation who had previously undergone decompressive surgery. Current recommendations regarding which patients should refrain from collision sports are made based on patients who have not had decompressive occipital craniectomy or upper cervical laminectomy. The fact that this patient had already undergone surgery did not exclude neural compression as a cause of his symptoms; postoperative changes can allow the cerebellum to compress the spinal cord and cause a functional Chiari malformation again.1 In addition, despite prior decompressive craniectomy, our patient was known to have a significantly abnormal cerebellar tonsillar descent (17 mm). Further complicating the task of making an appropriate diagnosis, there can be significant overlap between symptoms due to Chiari I malformation and symptoms due to concussion.2,7 Ultimately, the diagnosis of sports-related concussion was made in this patient when his symptoms improved over a 3-day period without any specific interventions relating to his malformation. Immediately obtained imaging findings that were unchanged from his previous imaging supported this diagnosis and ruled out traumatic changes to his Chiari I malformation as a cause of his symptoms. Because his symptoms were determined to be secondary to a concussion, he was not disqualified from contact sports. There are no specific guidelines regarding the amount of tonsillar herniation that is permissible for participation in contact sports, but it should be noted that this is recognized as an area of needed research.6
Implications for Clinical Practice
Much attention is rightly given to head injuries in sports, of which American football has the highest number of head injuries and receives the most publicity.7 Athletic trainers and physicians must be aware of head injuries and concussion symptoms in athletes and be prepared to intervene as necessary.
This particular case underscores the importance of being aware of an athlete’s medical and surgical history because it influences the initial differential diagnosis. Our patient’s history of Chiari I malformation and prior surgery raised the question as to whether there was traumatic change involving his previously decompressed posterior central nervous system. Sudden onset of symptoms due to even minor head trauma in patients with Chiari I malformation has been described in the literature and must be considered in the evaluation of this population of patients. Proposed mechanisms of previously asymptomatic malformations becoming symptomatic include direct mechanical effects on the affected central nervous system tissue or increased intracranial pressure causing a worsened herniation.8 Timely imaging was essential to ensure that this patient’s symptoms were due to concussion alone, as per the recommendations from the American Medical Society for Sports Medicine position statement on sports concussions.9 Typically, patients complaining of concussion symptoms should not undergo neuroimaging, but it was deemed necessary in this case because undetected neural compression could have had potentially devastating consequences.
Once structural pathology is ruled out, players can be started on a post-concussion return to play protocol, as was the case with this patient. Contraindications to returning to play include symptoms that are believed to be generated by structures around the foramen magnum or persistent neurologic symptoms. Previous history of craniectomy or craniotomy is not a direct contraindication to participation in contact sports.10
Although there are published studies regarding return to play after the diagnosis of asymptomatic Chiari I malformation, there is much less evidence regarding contact sports participation recommendations after craniectomy for this condition. Symptomatic Chiari I malformation and concussion share some similar features that can make initial diagnosis difficult. Prior decompressive surgery does not rule out Chiari-type compressive injuries of the brainstem and upper spinal cord because functional compression can still occur. The central nervous system should be imaged emergently via magnetic resonance imaging if there is clinical concern that structural pathology is the cause of the patient’s symptoms. Each player’s return to play schedule should be individualized according to the history, presentation, and recovery, but may be safely done when the diagnosis of concussion is made.
- Taylor FR, Larkins MV. Headache and Chiari I malformation: clinical presentation, diagnosis, and controversies in management. Curr Pain Headache Rep. 2002;6:331–337. doi:10.1007/s11916-002-0056-z [CrossRef]
- Callaway GH, O’Brien SJ, Tehrany AM. Chiari I malformation and spinal cord injury: cause for concern in contact athletes?Med Sci Sports Exerc. 1996;28:1218–1220. doi:10.1097/00005768-199610000-00002 [CrossRef]
- Meehan WP 3rd, Jordaan M, Prabhu SP, Carew L, Mannix RC, Proctor MR. Risk of athletes with Chiari malformations suffering catastrophic injuries during sports participation is low. Clin J Sport Med. 2015;25:133–137. doi:10.1097/JSM.0000000000000107 [CrossRef]
- Masson C, Colombani JM. Chiari type 1 malformation and magnetic resonance imaging [article in French]. Presse Med. 2005;34:1662–1667. doi:10.1016/S0755-4982(05)84244-7 [CrossRef]
- Kirschen MP, Illes J. Ethical implications of an incidentally discovered asymptomatic Chiari malformation in a competitive athlete. Continuum (Minneap Minn). 2014;20(6 Sports Neurology):1683–1687.
- Harrell BR, Barootes BG. The type I Chiari malformation in a previously asymptomatic college athlete: addressing the issue of return to athletic participation. Clin J Sport Med. 2010;20:215–217. doi:10.1097/JSM.0b013e3181dafc14 [CrossRef]
- Boden BP, Tacchetti RL, Cantu RC, Knowles SB, Mueller FO. Catastrophic head injuries in high school and college football players. Am J Sports Med. 2007;35:1075–1081. doi:10.1177/0363546507299239 [CrossRef]
- Wan MJ, Nomura H, Tator CH. Conversion to symptomatic Chiari I malformation after minor head or neck trauma. Neurosurgery. 2008;63:748–753. doi:10.1227/01.NEU.0000325498.04975.C0 [CrossRef]
- Harmon KG, Drezner JA, Gammons M, et al. American Medical Society for Sports Medicine position statement: concussion in sport. Br J Sports Med. 2013;47:15–26. doi:10.1136/bjsports-2012-091941 [CrossRef]
- Miele VJ, Bailes JE, Martin NA. Participation in contact or collision sports in athletes with epilepsy, genetic risk factors, structural brain lesions, or history of craniotomy. Neurosurg Focus. 2006;21:E9. doi:10.3171/foc.2006.21.4.10 [CrossRef]
Clearance for Contact Sport Recommendations in Athletes With Chiari I Malformation
|AUTHOR||DATE OF PUBLICATION||RECOMMENDATION|
|Masson & Columbani4||2005||No contact sports|
|Meehan et al.3||2014||Decision should be made on a case-by-case basis|
|Kirschen & Illes5||2014||Decision should be made in partnership with athlete (and parents, if a minor) after risks are explained|
|Harrell & Barootes6||2014||Decision should be made in conjunction with a neurosurgical opinion|