Spinal arachnoid cysts are a relatively uncommon lesion that may be either intra- or extradural, and intradural spinal arachnoid cysts are even less common. These cysts are usually asymptomatic but may produce symptoms by compressing the spinal cord or nerve roots suddenly or progressively. We present three cases in the pediatric age group with spinal intradural arachnoid cysts without a preceding history of trauma. Three patients with symptomatic intradural arachnoid cysts were investigated with conventional T1- and T2-weighted magnetic resonance imaging (MRI). The MRI scans demonstrated the intradural arachnoid cysts with slightly lower CSF signal intensity on the gradient echo images and slightly higher signal intensity on T1-weighted images. The first cyst was located at the level T12-L1 and compressed the conus medullaris, with neurogenic bladder and cauda equina syndrome for 2 months. The second was located at the level C5-T1 ventrally, with spastic gait and neurogenic bladder for 4 years. The other was located at T2-3 ventrally, with sudden onset of quadriplegia after jumping rope. The combined treatment of total resection and wide fenestration in our three patients produced an excellent return of neurologic function in each one, except for residual urinary disturbance in case 2. Intradural spinal arachnoid cysts appear to result from an alteration of the arachnoid trabeculae; some such cysts are ascribed anecdotally to previous trauma or arachnoiditis, whereas the majority are idiopathic and congenital. The majority of intradural spinal arachnoid cysts occur in the thoracic region and most are dorsal to the neural elements. Only 10 cases have been reported in which the intradural arachnoid cysts were located anterior to the cervical spinal cord, of which 8 were in the pediatric age group, like our case 2. Myelography, postcontrast CT myelography and MRI have been demonstrated as useful for the diagnosis of intradural arachnoid cysts. MRI is the imaging modality of choice, and the extent, size and nature of the lesion in our cases were well demonstrated by MRI. Surgical treatment is necessary if progressive neurological dysfunction appears in the course of spinal cord compression. Complete surgical excision of the cysts is the best choice of treatment, and wide fenestration and shunting of the cyst to the peritoneum, pleural cavity or right atrium were the modalities of choice. MRI offers a noninvasive and effective means to make the diagnosis of arachnoid cysts easier. Intradural arachnoid cysts may cause progressive myelopathy; however, the postoperative prognosis is good if the operation is performed prior to neurologic deficits.
Copyright 2001 S. Karger AG, Basel