Chiari malformation was also known as a group of congenital malformations involving the brainstem, cerebellum, upper spinal cord, and surrounding bony structures. Type I is the most common, and characterized by herniation of the cerebellar tonsils through the foramen magnum into the cervical spinal canal. The pathogenesis of Chiari malformation associated with syringomyelia was still a subject of much debate. As follows: (1) The theory of fluid mechanics[2]; (2) The theory of separated pressure of intracranial and spinal canal[3]; (3) The theory of the infiltration of cerebrospinal fluid in parenchyma of spinal cord[4]. Some authors think that the mechanism of Chiari malformation and syringomyelia induced scoliosis may be: syringomyelia damage spinal cord anterior horn and pyramidal tract, caused unbalance of paraspinal muscle, which led to scoliosis[5].
Charcot arthropathy was characterized by the gradual destruction of the affected joint or joints, in patients most with neurosensory loss. Charcot arthropathy is usually seen in weight-bearing joints such as ankle, knee, and hip, while the localization of involved joint changes according to the underlying neurological pathology[6]. Charcot arthropathy occurred most commonly in patients with diabetic neuropathies, and the incidence of diabetic Charcot arthropathy has been reported to range from 0.1% to 5.0%[7]. This destruction happened mostly in foot and ankle[6]. Secondly, Charcot arthropathy can be developed in patients with syringomyelia, and then the shoulder and elbow are the most frequently involved joints in syringomyelia[6]. Charcot arthropathy secondary to syringomyelia mostly involved single joint and involvement of multiple joint is rare[8, 9]. Furthermore, the joints mostly involved are the hip and knee in tabes dorsalis[6]; spine in tertiary syphilis, post–spinal cord injury[10], and congenital insensitivity to pain[11]; and tarsometatarsal and subtalar joint in chronic alcohol abuse[12].
The pathogenesis of neuroarthropathy was in debate. Many theories have been proposed to explain the etiology of Charcot arthropathy, including (1) osteopenia owing to increased volume of blood flow associated with autonomic neuropathy; (2) bone failure because of abnormal stress on the bones and joints related to muscle imbalances resulting from sensorimotor neuropathy; (3) joint subluxation due to ligamentous stretching associated with joint effusion; and (4) the loss of protective mechanism in body due to sensory disturbance caused by neuropathy[13, 14].
The patient with no significant medical history in the past, except for scoliosis 8 years prior to his presentation to our clinic, visited to our hospital because of complaining the painless swelling and limitation of motion in his joint. He denied any constitutional symptoms, trauma, or pain in the upper extremities at this time of presentation. Then radiographic surveys of the joint were done and the severe destruction in his left shoulder was found. MRI was done and we found that he had syringomyelia complicating with Chiari malformation, which was supposed to be the cause of destruction in his joint.
Once Charcot arthropathy was found, it was mostly in advanced stage and hard for treatment. Although satisfactory middle and long-term results are described in recent reports[15, 16], the results of total replacement arthroplasty for the Charcot joints have been disappointing. It is often difficult to distinguish early-stage Charcot arthropathy from other disorders, because no characteristic clinical, radiographic or laboratory finding can confirm the diagnosis of this disease in early stage. As was the case in our report, in his initial visit 8 years ago, there was no examination except for plain X-ray, and the patient had no follow-up visits until 8 years after the initial visit. If MRI had been performed, syringomyelia complicating with Chiari malformation, which was the cause of Charcot arthropathy, would been evidenced. Thus, early diagnosis of Charcot arthropathy would be possibly evidenced. Therefore, we offer this observational case in the hope of sharing some of our experiences with this relatively rare disease, and we recommended that if patient suffering from scoliosis visited in clinic, further examination such as MRI and regular follow-up should be carried out. And early-stage of this devastating disease caused by syringomyelia and Chiari malformation may be diagnosed easily. Perhaps in the future, some of our findings can be used to generate hypotheses for upcoming cohort studies and randomized controlled trials.
