Prepared by Amar Damodar, MD, MBBS, Clinical Assistant Instructor, and Patrick Siaw, MD, Clinical Assistant Professor of Medicine, University at Buffalo School of Medicine and Biomedical Sciences, Sisters of Charity Hospital, Catholic Health System, Buffalo, NY
A 58-year-old black woman with an 8-year medical history significant for seizure disorder and chronic headaches presented to the hospital with heaviness, swelling, tingling, and numbness of her right shoulder, all of which radiated to her right upper extremity. She also reported insidious weakness in her right upper extremity, which she first noticed years earlier after having difficulty carrying her purse. She was not aware of weakness in her legs, but further questioning revealed some loss of balance with slight recent weakness in the right lower extremity. The patient also noted increased urinary frequency over the past 6 months.
During the neurological examination, significant findings included a diminished pinprick sensation in the third division of the right trigeminal nerve; significant proximal muscle weakness in the right upper extremity compared with the left upper extremity; and absent biceps and triceps reflexes bilaterally. Sensitivity to light touch in the right upper extremity was decreased more than in the left upper extremity, but pain sensation was within normal limits in both extremities. The patient's gait was minimally ataxic, and she had a positive Romberg's test. Magnetic resonance imaging of the cervical spine was obtained (Figure).
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| Figure |
What's Your Diagnosis?
- Polyneuropathy
- Cervical disk prolapse
- Multiple sclerosis
- Syringomyelia due to Chiari I malformation
Quiz Answer
Syringomyelia due to Chiari I malformation—The magnetic resonance image (MRI) shows a cervical syrinx that extends to the upper thoracic spinal cord and a tonsillar protuberance approximately 7 mm beyond the foramen magnum (Figure). Based on these findings, a diagnosis of syringomyelia in association with Chiari I malformation was made.
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| Figure—MRI of the cervical spine (sagittal view) showing a
cervical syrinx and a tonsillar protuberance (arrows). |
Clinical findings in our patient highlighted dissociate anesthesia in a cape-like distribution suggestive of central cord lesions. Polyneuropathy and multiple sclerosis are unlikely to present this way. There were no signs of cervical disk prolapse and no significant MRI findings beyond the cervical syrinx and the tonsillar protuberance.
Professor Hans Chiari, an Austrian pathologist, first described abnormalities of the brain at the junction of the skull and the spine in 1891.1 These came to be known as Chiari malformations and are categorized as types I, II, III, and IV, based on the severity of the abnormality. Chiari malformations are reported to occur in approximately 1 in 1,000 individuals, with type I being the most common manifestation.1
Chiari I malformations occur during fetal development, but they are generally diagnosed in adolescents and adults. This malformation is characterized by herniation of more than 4 mm of the cerebellar tonsils through the foramen magnum into the cervical spinal canal. As a result of this displacement, the normal pulsations of cerebrospinal fluid between the spinal canal and the intracranial space may become blocked.
Chiari I malformations may be associated with hydromyelia or syringomyelia, the latter of which was observed in our patient. Although the term "hydromyelia" is sometimes used interchangeably with "syringomyelia," these conditions are different. Hydromyelia is defined as an abnormal widening of the central canal of the spinal cord and is almost always associated with infants and children who have hydrocephalus or birth defects, such as Chiari II malformations and Dandy-Walker malformation.2,3 In contrast, syringomyelia features a closed cavity and is typically observed in adults with Chiari I malformations, but it can also occur secondary to trauma, arachnoiditis, meningitis (bacterial more commonly than viral), spinal tumors, or tethered spinal cord syndrome. The end result of hydromyelia and syringomyelia are the same: a spinal cord abnormality that causes a wide range of neurological symptoms.
Syringomyelia symptoms are diffuse, variable, and nonspecific. Loss of sensitivity, especially to hot and cold; muscle weakness; and spasticity in a cape-like distribution are suggestive of central spinal cord lesions. Scoliosis, loss of bowel and bladder control, discrete motor impairment, and chronic pain are other signs of a cervical syrinx. The presence of chronic headaches is often concurrent with Chiari I malformations.4
Treatment of Chiari malformations and syringomyelia depends on several factors, including the type of malformation, rate of syrinx growth and the resultant anatomical changes, as well as the patient's symptoms. Asymptomatic Chiari I malformations should not be treated, and surgery is reserved for patients who require relief of symptoms or in whom syrinx growth must be halted.2
References
- Arnold Chiari Malformation. Available at: uscneurosurgery.com/Disorders_includes/arnchiari1.php. Accessed February 20, 2008.
- DiLorenzo N, Cacciola F. Adult syringomielia. Classification, pathogenesis and therapeutic approaches. J Neurosurg Sci. 2005;49:65-72.
- National Institute of Neurological Disorders and Stroke. NINDS Syringomyelia Information Page. Available at: www.ninds.nih.gov/disorders/syringomyelia/syringomyelia.htm. Accessed February 17, 2008.
- Hauser SL, Ropper AH. Diseases of the Spinal Cord. In: Kasper D, Braunwald E, Fauci A, et al, eds. Harrison’s Principles of Internal Medicine. 16th ed. New York, NY: McGraw Hill; 2005.
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