404
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CUTE
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DIOPATHIC
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YRINGOMYELIA
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A C
ASE
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EPORT
June-Kai Chen, Chia-Hsiu Chen, Chia-Ling Lee, Tien-Wen Chen,1 Ming-Cheng Weng,1 and Mao-Hsiung Huang
Department of Physical Medicine and Rehabilitation, Kaohsiung Medical University Hospital, and 1Department of Physical Medicine and Rehabilitation,
Kaohsiung Municipal Hsiao Kang Hospital, Kaohsiung, Taiwan.
There have been isolated reports in the literature of the natural history and less than complete knowledge of the epidemiology and pathophysiology of syringomyelia. This article describes a clinically acute-onset abnormal patient with localized dilatation of the central canal of the spinal cord who had no evidence of present or prior Chiari’s malformation, trauma, infection, tumor, or other predisposing pathologic condition. It is suggested that this distinct condition be labeled “acute idiopathic syringomyelia”.
Key Words: acute, idiopathic, syringomyelia (Kaohsiung J Med Sci 2004;20:404–9)
Received: February 18, 2004 Accepted: May 12, 2004 Address correspondence and reprint requests to: Dr. Mao-Hsiung Huang, Department of Physical Medicine and Rehabilitation, Kaohsiung Medical University Hospital, 100 Tzyou 1st Road,
Kaohsiung 807, Taiwan. E-mail: [email protected]
Syringomyelia is a process that involves dilatation of the central canal of the spinal cord or formation of abnormal tubular cavities in its substance. Syringomyelia is not a single disease, but rather a descriptive term for any fluid cavity in the spinal cord. Regardless of the underlying etiology, the symptoms and signs of syringomyelia are related to the location, size, and extent of the cavity. With the advent of magnetic resonance imaging (MRI) and im-provements in surgical procedures for decompression of the cavity, syringomyelia is an increasingly recognized cause of disability and even death in patients with clinical symptoms and signs of central spinal cord lesions.
In this article, we describe a case of acute syringomyelia of the cervical cord and term this distinct condition “acute idiopathic syringomyelia” to distinguish it from syringo-myelia secondary to causes such as Chiari’s malformation, trauma, infection, or neoplasm.
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RESENTATIONA 19-year-old woman presented with 2-day proximal upper-limb weakness that had developed abruptly and worsened during the first day of her illness. Over the same period, she became aware of unsteadiness of gait. No symptoms of respiratory or gastrointestinal infection were noted. There were no other neurologic symptoms, in particular, no sphincter disturbance or back pain. There was no medical, trauma, or family history of note.
On examination, higher cerebral function and cranial nerves were normal. The strength of upper-limb movements was reduced to a greater extent on the right than on the left (Table 1). Deep tendon reflexes were absent in the arms. In the lower limbs, there was some reduction in strength bilaterally, and bilateral hyperactive deep tendon reflexes with Babinski signs (Table 1). Gait was ataxic, but there was no heel/shin ataxia. Proprioception and discriminatory sen-sations were normal, but pain and temperature sensen-sations were diminished in the bilateral C5 through T1 dermatomes. Examination of other systems revealed no abnormality. The patient was dependent for activities of daily living, including feeding, grooming, hygiene, dressing, and ambulation (Table 2). Routine hematologic and biochemical investigations, including thyroid function, serum B12, and serologic tests
for syphilis, gave normal or negative results. Nerve con-duction studies were unremarkable. Cerebrospinal fluid investigation was refused.
In radiologic investigations, cervical spine and chest roentgenography was normal. MRI demonstrated a spinal syrinx between C2 and C6 (Figure 1). The patient sub-sequently underwent suboccipital craniectomy with C1 laminectomy and C3 through C5 laminectomy to enable craniocervical decompression of the syrinx. Dural vascular engorgement between the C3 and C5 vertebral bodies was found at operation.
Postoperatively, full participation in a comprehensive rehabilitation program was begun, with steady improve-ments in independence with ambulation at the commu-nity level, and independence in activities of daily living. Table 2 depicts the patient’s functional status as evaluat-ed by the Barthel index [1]. We comparevaluat-ed her functional
Table 1. Comparison of motor strength before and after a 1-month comprehensive rehabilitation program (results expressed in muscle strength grade)
Before management 1 month after management
Right Left Right Left
Elbow flexors 2 3 3 5 Wrist extensors 3 3 5 5 Elbow extensors 3 3 3 5 Finger flexors 4 4 5 5 Finger abductors 4 5 5 5 Hip flexors 4 4 5 5 Knee extensors 4 4 5 5 Ankle dorsiflexors 5 5 5 5
Big toe extensors 5 5 5 5
Ankle plantar flexors 5 5 5 5
Table 2. Functional status as evaluated by the Barthel Index before and after a 1-month comprehensive rehabilitation program
Before management 1 month after management
Feeding 5 10 Grooming 0 5 Bowel control 10 10 Bladder control 10 10 Wheelchair transfer 10 15 Toilet transfer 5 10 Dressing 5 10 Bathing 0 5 Level walking 10 15 Stairs 5 10 Total 60 100
status before and after the 1-month comprehensive reha-bilitation program. Markedly improved motor strength with only a three-fifths strength deficit involving the right proximal upper limb and unchanged sensory deficit were noted. A comparison of motor strength before and after the comprehensive rehabilitation program is shown in Table 1. Twelve months after surgery, the minimal improvement in strength in the right proximal upper limb continued. The sensory deficit remained unchanged. Follow-up MRI revealed a reduction in syrinx size (Figure 2).
D
ISCUSSIONSyringomyelia has been used to refer to a syndrome caused by cavitation of the spinal cord adjacent to the central canal, or to any cyst of the spinal cord or dilatation of the central
canal and/or its extension into the cord substance [2]. The incidence of syringomyelia is unknown, but it was pre-viously thought to be rare [3]. It occurs more frequently in males, and is usually first detected in the third or fourth decades of life. It is uncommon in children or the elderly. Since the advent of computerized tomography (CT) and MRI, there has been an apparent increase in the incidence of syringomyelia. This may represent the detection of previously undiagnosed subclinical cases and not an increased incidence of disease.
The etiology of this disease is variable [4,5]. The dilata-tion was thought to be primarily developmental in origin, but some postnatal conditions were found to induce the same condition. Barnett, in his seminal monograph on syringomyelia, proposed a more expansive definition and classified the syndrome into five groups according to the presumed causal pathophysiology [6]. The increased intraspinal pressure of such defects in the present patient would result from idiopathic syringomyelia. Unrecognized
trauma, coughing, or other such phenomena may initiate development of syringomyelia in the absence of a medical and trauma history. No Chiari’s malformation or any skeletal malformation of the craniocervical junction was found.
The pathophysiology of syringomyelia is still debated, and numerous reviews on the subject are available [7,8]. Most articles agree that the syrinx is subject to continuous pulsatile pressure from outside the spinal cord and to sud-den rises in pressure associated with coughing, sneezing, and Valsalva maneuvers. Shunting the contents of the syrinx to a low-pressure extraspinal site offers the best chance of maintaining the pressure within the syrinx at a reduced level and dissipating the effects of sudden pressure changes. There is clinically variable presentation in syringomye-lia. Cord cavitation causes slow but relentlessly progres-sive symptoms and signs, depending on its location, ex-tent, and frequent asymmetry [4]. The symptoms usually consist of any combination of motor and sensory dysfunc-tion. Disassociated sensory findings of impaired pain and
A
Figure 1. Preoperative unenhanced sagittal magnetic resonance images of the craniocervical junction and cervical spine show the dilated central canal within the cervical spinal cord (arrows): (A) T2-weighted; (B) T1-weighted.
A
Figure 2. Postoperative unenhanced sagittal magnetic resonance images of the craniocervical junction and cervical spine (12 months after surgery) demonstrate reduction in syrinx size: (A) T2-weighted; (B) T1-weighted.
B
temperature with the preservation of light touch sensation with “cape-like” suspended sensory loss are the classic presentation. The earliest sensory changes usually affect the hands, but a careful examination may disclose a similar deficit affecting the neck, shoulders, upper chest, and back. Motor dysfunction often accompanies the sensory loss, resulting in progressive atrophy of the musculature of the upper extremities. This often manifests in skeletal mal-formations, principally kyphoscoliosis. The progressive atrophy is seen with other lower motor neuron findings such as muscle fasciculation and areflexia. Later in the di-sease course, upper motor neuron signs arise in the legs due to involvement of the lateral columns of the spinal cord. The last neurologic functions to be lost are vibratory and position senses in the lower extremities, which occur after the syrinx extends to affect the posterior columns of the spinal cord. Less common manifestations include preganglionic Horner syndrome secondary to involvement of the intermediolateral cell column of the lower cervical and first thoracic segment
of the spinal cord containing sympathetic neurons [9–13]. The clinical findings of this case are similar to those reported in previous series. In retrospect, the abrupt onset of proximal upper-limb hypotonic paresis and the cervical dural vascular engorgement found at surgery were the most intriguing features. The clinical presentation was more suggestive of concomitant extrinsic cord compression than of an intramedullary lesion alone. The previous idiopathic syrinx was clinically silent and of indeterminate duration. We believe that syringomyelia developed in our patient as a consequence of localized cord compression due to the distended dural vascular engorgement. It has been pos-tulated that cord compression results in focal necrosis and progressive cavitation [7]. This hypothesis is supported by the patient’s sustained clinical improvement following surgical decompression.
Ever since the first case reported by Etienne in 1564, the epidemiology, natural history, pathophysiology, and most prudent form of treatment of syringomyelia have
re-mained controversial. As a clinical entity, idiopathic syrin-gomyelia is a relatively rare condition. To our knowledge, there are no reports describing idiopathic syringomye-lia with an acute course. Due to the variation in the natural history, anatomy, surgical treatment, and follow-up pe-riods reported to date, very few firm conclusions can be drawn regarding syringomyelia. Long-duration follow-up is required for a better understanding of all aspects of syringomyelia. We emphasize the need to be aware of this entity. This is particularly important because of the good prognosis and excellent chance of recovery if pa-tients are properly managed.
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