A type I Chiari malformation is a congenital neurological disorder in which the cerebellar tonsils are displaced downward through the foramen magnum. This displacement can cause cerebrospinal fluid (CSF) outflow obstruction and formation of a syrinx. The prevalence of Chiari type I malformation is estimated by the National Institute of Health to be 1 in every 1,000 individuals (7). The most common presenting symptom of Chiari type I malformations is suboccipital headache, commonly described as a heavy, crushing, pressure-like ache extending from the vertex superiorly to the neck and shoulders inferiorly. Other common presentations include ocular symptoms, such as retrobulbar pain, photophobia, diplopia, flashers, floaters, blurred vision, visual field cuts, otoneurological symptoms such as dizziness, disequilibrium, vertigo, hearing loss, and tinnitus, and symptoms of cervical syringomyelia, such as paresis and a cape-like loss of pain and temperature sensation in the back and upper extremities (3,11,12,19). Symptoms are classically exacerbated by Valsalva maneuvers or other activities that increase intrathecal pressures, such as coughing, straining, or laughing (5,19).
Chiari type I malformations presenting as unilateral pain and weakness in isolated muscle groups are unusual. We present here a case of Chiari type I malformation presenting as unilateral shoulder pain, weakness, and muscle atrophy in an otherwise healthy collegiate lacrosse athlete. His presentation to us was in part prompted by his inability to play as well as failure to improve with physical therapy. This case both illustrates an unusual presentation of an uncommon disorder and stresses the importance of working up cervical spine pathologies when considering shoulder-related complaints in athletes.
Presentation of the Case
History and examination
A 20-year-old man was referred to our Sports Medicine clinic for consultation and third opinion regarding left shoulder pain and weakness. The patient had experienced a left shoulder dislocation 6 years ago and underwent surgery for shoulder instability at that time. However, since that time, he had been complaining of progressive shoulder pain and weakness. He tried physical therapy without success and presented to the clinic due to his inability to participate in collegiate lacrosse for the past year.
On examination, the patient had marked atrophy of the left trapezius and deltoid. On motor examination, the left trapezius exerted 3/5 of the strength, the left deltoid exerted 3/5, and the left biceps exerted 4/5; otherwise he performed at full strength. Notably, he was unable to lift his left arm above his left shoulder, although his passive shoulder range of motion was full. Sensory examination was unremarkable. He was hyporeflexic in both upper extremities and had positive Hoffmann’s reflexes bilaterally. Hawkin’s, Neer’s, and O’Brien’s tests were negative.
The plain films of the left shoulder were unremarkable. The plain films of the cervical spine were notable only for straightening of the expected cervical lordosis. Magnetic resonance imaging (MRI) of the cervical spine showed a Chiari I malformation with a 21-mm cerebellar tonsillar herniation below the foramen magnum through the C1 and C2 arches as well as syringomyelia of the cervical spinal cord (Fig. 1).
Given his MRI findings, the patient was referred to our Spine Center for further evaluation. Risks and benefits of surgical intervention were discussed and the patient opted for surgical treatment. He underwent suboccipital craniectomy, resection of the C1 arch, and partial resection of the C2 arch for decompression of his Chiari type I malformation. In addition, duraplasty was performed from the level of the occiput to C2 using AlloDerm (LifeCell, Bridgewater, NJ).
At 4 wk of follow-up, the patient reported decreasing left shoulder pain. His incision was well healed. By 2 months of follow-up, he had regained full strength in his deltoid and much of his muscle bulk. He had completed his prescribed physical therapy and returned to regular exercises at the gym. Repeat MRI of the cervical spine at 2 months after his surgery showed good decompression of the cerebellar tonsils with residual syrinx, as expected (Fig. 2). He was permitted to return to play contact sports.
Chiari type I malformations are defined as herniations of the cerebellar tonsils at least 5 mm below the foramen magnum (12). Although asymptomatic Chiari I malformations can be followed conservatively for many years, symptomatic patients do well with surgical treatment. Suboccipital-cervical decompressions have been shown to improve symptoms in 75% to 90% of patients with long-term follow-up (1,19). Duraplasty at the time of decompression has been shown to decrease rates of symptomatic recurrence nearly fourfold compared with decompression alone (13). Sixty-five percent of Chiari type I malformations are associated with syringomyelia (11), a negative prognostic sign for symptomatic improvement after surgery (16). However, the majority of patients do experience decreased syrinx size, as our patient did, and no further progression of myelopathy with decompression (15). Our patient was fortunate to get resolution of his neurological symptoms.
The most common clinical presentations of Chiari type I malformations arise from increased intracranial pressures. More than 80% of patients present with suboccipital headaches, followed by ocular disturbances (retrobulbar pain, photophobia, diplopia, flashers, floaters, blurred vision, and visual field cuts), otoneurological symptoms (dizziness, disequilibrium, vertigo, hearing loss, and tinnitus), gait ataxia, and generalized fatigue (3,11,12,19). Presenting symptoms isolated to specific muscle groups are rare and, when they occur, tend to involve muscles innervated by the lower cranial nerves such as isolated neuralgias of the trigeminal nerve and the glossopharyngeal nerve (9,14). Laufer et al. (8) reported two pediatric patients presenting with isolated weakness in one lower extremity, either in ankle dorsiflexion or plantarflexion, both of whom improved significantly with surgical decompression. To the knowledge of the authors, this is the first described case of Chiari type I malformation presenting with isolated unilateral shoulder pain and associated trapezius, deltoid, and biceps weakness. In this case, the associated syringomyelia likely contributed to the patient’s upper extremity weakness.
When Chiari type I malformations present in the context of competitive sports, a unique and interesting challenge arises in clinical management. Frogameni et al. (6) previously reported a case of a 20-year-old male football player who presented with 10 min of left-sided hemiparesis after weightlifting and was found to have a Chiari I malformation with cervical syringomyelia. He was advised to stop contact sports. Callaway et al. (4) reported a case of an 8-year-old male football player presenting with bilateral thigh numbness and tingling after an axial blow to the head during a tackle who was found to have a Chiari type I malformation. The patient was initially advised against contact sports but ultimately proceeded to have suboccipital decompression. Walk (20) reported a case of a 20-year-old male football player who was seen with left knee pain, found to have a Chiari type I malformation with cervical syringomyelia, and treated with suboccipital decompression and C1 laminectomy. It is important to consider cervical spine disease, including congenital disorders, when examining young athletes of contact sports, especially as they begin to compete at the collegiate level where the level of exertion and impact can unmask previously quiescent pathology.
Little is known about the safety of return to play for contact sports athletes with Chiari type I malformations. It has been postulated that disturbances in the normal CSF pathway and circulation may hinder the normal ability of CSF to buffer the brain on high-velocity impacts (2). For this reason, and for fear of progression of symptoms, patients who are symptomatic are generally advised against further participation in contact sports (10). For asymptomatic patients, however, a Chiari type I malformation is not an absolute contraindication to contact sports, although a discussion should take place about the possibility of symptom occurrence or severe neurological injury (17). Some surgeons advise asymptomatic patients to forgo participation in contact sports if they have associated syringomyelia, obliteration of the CSF space, or indentation of the anterior medulla (10). In the authors’ opinion, it is appropriate for a neurosurgeon to be involved in decisions of sports clearance for athletes with Chiari I malformations. Patients who have had surgical decompression are not prohibited from sports participation (17).
We have presented a case of Chiari type I malformation in a healthy 20-year-old collegiate lacrosse player with isolated left shoulder pain, weakness, and muscle atrophy, with an unusual presentation of a rare, congenital disorder of the spine. Cervical pathology frequently manifests with shoulder symptoms. In a review of orthopedic clinic patients with shoulder complaints, 3.6% of the patients were found to have spine pathology (18). The present case highlights the importance of considering cervical spine disease in patients with shoulder symptoms.
The authors declare no conflicts of interest and do not have any financial disclosures.
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