An Unusual Case of a Conus Hanging by a Thread.

We report a rare cause of paraparesis in a 2-year-old girl. Along with lower limb weakness, she presented with a neurogenic bladder and lower limb deformities. Her magnetic resonance imaging showed multiple dorsolumbar segmentation defects and a dysgenetic spinal cord segment between T10 and S1. A thin septum connected the lower end of the normal cord to a bulky conus at S1-2. These features were suggestive of type 1 segmental spinal dysgenesis. The findings were confirmed at surgery, and the child was referred for supportive care. Copyright:

A 2-year-old girl presented with bilateral clubfoot, progressive spastic paraparesis, and urinary incontinence. Magnetic resonance imaging (MRI) showed multiple segmentation defects in the dorsolumbar vertebrae. The lower end of the normal cord was seen at T10 with a thin septum connecting it to a bulky conus at S1-2 [Figure 1]. There was no evidence of kyphoscoliosis, instability, or any extraspinal anomalies. The radiological diagnosis was that of type 1 segmental spinal dysgenesis (SSD). In view of her gradual neurological deterioration, exploratory surgery was performed under neurophysiological monitoring to rule out any tethering element(s). Following laminectomy, a thin delicate strand of neural tissue was seen connecting the normal cord to a low-lying conus at S1 [Figure 2]. Nerve roots were seen emanating from the conus, most of which were confirmed to be functional by positive triggered electromyographic stimulation. The filum terminale appeared normal, and after confirming that there were no tethering elements, the dura and wound were closed. There was no postoperative change in her clinical condition, and she was referred for supportive care.

Figure 1

Sagittal MRI showing (A) normal spinal cord at T9-10 level (large white arrow), thin strand (black arrow) connecting to a bulky conus at S1-2 (small white arrow). Axial sections showing (B) normal cord at T9, (C) septum at T11, and (D) conus at L5-S1

Figure 2

Intraoperative image showing a thin strand of neural tissue (small white arrow) leading to a bulky conus at L5-S1 (large white arrow). Normal nerve roots (black arrow) seen arising from the conus

SSD is a rare, congenital syndrome, characterized by segmental agenesis or dysgenesis of the lumbar or thoracolumbar spine, segmental abnormality of the cord and nerve roots, congenital paraplegia or paraparesis, and lower limb deformities.[1] On MRI, SSD has a typical appearance with normal upper spinal cord, a hypoplastic spinal cord at the dysgenetic levels, and normal cord below. SSD has been classified into type 1 (primary cord hypoplasia) and type 2 (cord hypoplasia secondary to canal stenosis from dysmorphic vertebrae).[2]

The role and timing for surgical intervention in SSD are not well established.[34] Surgery is indicated in cases of possible tethering, canal stenosis, or progressive cord injury from kyphoscoliosis. The optimal timing for performing arthrodesis in the latter subset of patients remains unclear. Decompressive surgery is unlikely to benefit patients with congenital paraplegia.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.