Syringomyelia: An Uncommon Cause of Myelopathy in the Geriatric Population

To the Editor: Myelopathy is a relatively common finding in the geriatric population, resulting from many different causes. The most common (and to some extent treatable) causes for myelopathy include structural abnormalities such as cervical spondylosis, trauma, and tumor.1 We report on one unusual cause of myelopathy, syringomyelia, secondary to the Arnold-Chiari I (ACM-I) malformation, its presentation and manifestation in an elderly patient. The presentation of syringomyelia and ACM-1 in elderly patients is rare—a literature search revealed only one other case report.2 The patient is an 80-year-old African-American woman who presented with complaints of gait difficulty and anesthetic, dysesthetic, and paraesthetic sensory abnormalities—especially in the hands, which she stated, “feel like sandpaper.” Her complaints had begun approximately 5 years previously with cervical pain and numbness in a cape-like distribution. She had been diagnosed 2 years previously with extensive syringomyelia extending from vertebral levels C2 to T4. A suboccipital craniectomy and a C1-C2 laminectomy with duraplasty was recommended, but the patient refused intervention. Her current complaints included progression of her symptoms, extending to her right pinna, difficulty with walking, and frequent burns of her fingers while cooking. She also reported compulsive nail biting, resulting in mutilation of several digits. Her social and medical histories were noncontributory. She reported no other symptoms of visual, breathing, swallowing, or bowel and bladder dysfunction. The general examination was significant for extensive healed and open ulcers of the fingertips bilaterally. A complete neurological examination revealed anesthesia to temperature involving the right scalp, face, and pinna. Motor function was 4 out of 5 on the right side and 5 out of 5 on the left side, with normal bulk and tone bilaterally. Sensory examination demonstrated anesthesia for pinprick and temperature in the entire upper extremities bilaterally. Coordination was intact, but gait was unsteady. Reflexes were absent, with the exception of symmetric dorsiflexion of the great toes bilaterally. The differential diagnosis included progressive syringomyelia with syringobulbia. A magnetic resonance image and laboratory studies were obtained (Figure 1). The patient was re-referred to a neurologist, neurosurgeon, and physiatrist. She was unsuccessfully treated with ibuprofen, gabapentin, nortriptyline, and sertraline. During a trial of gabapentin, the patient significantly reduced her self-mutilating behavior of compulsive nail biting. T1 weighted magnetic resonance imaging of the cervical and upper thoracic spine. The cerebellar tonsils descend below the foramen magnum—indicative of the Arnold-Chiari I malformation. A central cavitation is evident from the hypointense signal within the central portion of the cervical spinal cord. Syringomyelia represents an abnormal fluid cavity within the spinal cord (syrinx). It is an uncommon problem with prevalence of less than 1 in 10,000,3, 4 but it is more common (60–70%) in individuals with congenital herniation through the foramen magnum of the cerebellar tonsils (ACM-I).5 Most individuals with this abnormality are diagnosed well before age 65.6 The manifestations of syringomyelia are protean. Symptoms referable to dysfunction of the brainstem and high cervical spinal cord include headache, neck pain, abnormal eye movements, trigeminal dysesthesia, hearing loss, and tinnitus. Autonomic symptoms may include dizziness or recurrent syncope and bowel and bladder abnormalities. Other symptoms include dysesthetic pain, paresthesiae, and dysphagia. Functional disability often results, especially with the development of ataxia and weakness.7 The differential diagnosis of syringomyelia includes multiple causes, characterized according to mechanism of injury: mechanical—cervical spondylosis, trauma; neoplastic—spinal cord tumor; inflammatory—multiple sclerosis, Devic's disease, transverse myelitis; neurodegenerative-amyotrophic lateral sclerosis, spinal and muscular atrophy, spinocerebellar atrophy, Freidrich's ataxia; metabolic—B12 deficiency; infectious—syphilis, tuberculosis, human T-lymphocyte virus type I.8 In the setting of the ACM, abnormal spinal cord hydrodynamics, resulting in central cavitation, are thought to result from a compressive effect of the tonsils on the proximal spinal cord.4 Treatment options are limited, but most often require surgical intervention, especially in the earliest symptomatic stage of the disease, and include limited craniocervical decompression with or without dura opening, decompression and lysis of adhesions with or without resection of tonsils, decompression and plugging of obex and stenting of the fourth ventricle, ventral decompression (resection of the odontoid process), and syringosubarachnoid shunting.9 Nonsurgical approaches to syringomyelia are limited. Options include modulation of pain, paresthesiae, and dysesthesia with a variety of agents, including gabapentin, amitriptyline, nortriptyline, anticonvulsants, and nonsteroidal antiinflammatory drugs. Other treatments are ongoing rehabilitative therapy and supportive care. The myelopathy associated with syringomyelia may be devastating. Gait abnormalities, weakness, and sensory disturbances, further exacerbated by this condition, contribute to functional limitations leading to loss of independence. The case described here is one such example of the morbidity associated with the condition but also exemplifies some of the less common but potentially remediable conditions when evaluated in the early stages of disease.10