PMC8769440_01
Radiological images of the patient diagnosed with iNPH at the age of 70 years. (A and B) Head T1-weighted MRI revealed tight convexity sulci and an enlarged sylvian fissure (coronal section) (A) as well as enlarged ventricles represented by an Evans' index of 0.34 (axial section) (B), indicating DESH, typically observed in iNPH. (C) Preoperative lumbar spine T2-weighted MRI showing absence of any abnormalities. (D) An abdominal radiograph showing proper implantation of the LPS system. iNPH: idiopathic normal pressure hydrocephalus, MRI: magnetic resonance imaging, DESH: disproportionately enlarged subarachnoid-space hydrocephalus, LPS: lumboperitoneal shunt.
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F1
Magnetic resonance imaging (MRI) of the brain showed the typical appearance of disproportionately enlarged subarachnoid-space hydrocephalus (DESH), with an Evans' index of 0.34, compatible with probable iNPH (Fig. 1A and 1B). The lumbar spine did not show any abnormalities at that time (Fig. 1C). The patient underwent surgical intervention, in which LPS was implanted using a Codman-Hakim programmable valve with a siphon guard system (Itegra LifeSciences, Princeton, NJ, USA) (Fig. 1D).
Radiological images of the lumbar spine of the patient showing manifestation of cauda equina syndrome at the age of 78 years. (A) Sagittal images of CT showing the lumbar catheter properly located in the spinal canal from the L3/4 to the L2 level, without snaking. (B and C) MRI revealing an extradural mass compressing the spinal dural sac toward the anterior side, at the L3/4 level, with a hypo- and iso-intensity on the T1-weighted image (B) and hyper-intensity on T2 fat suppression images (C), consistent with an EDAC. (D) Schematic drawings showing the relationship between the lumbar catheter and the EDAC. CT: computed tomography, MRI: magnetic resonance imaging, EDAC: extradural arachnoid cyst.
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F2
Computed tomography (CT) revealed that the lumbar catheter of the LPS ran through the spinal canal, without snaking from the L3/4 to the L2 level (Fig. 2A). Conversely, MRI indicated the presence of an extradural fluid-containing mass compressing the spinal dural sac toward the anterior side at the L3/4 level (Fig. 2B and 2C). This mass appeared to be on the lumbar catheter (Fig. 2D) and was consistent with an EDAC indirectly compressing the cauda equina.
(A and B) MRI of the lumbar spine taken one month after conversion of the LPS to VPS (T1-weighted [A] and T2 fat suppression [B] images revealing restoration of the spinal dural sac and the cauda equina, as well as shrinkage of the cyst at the L3/4 level. MRI: magnetic resonance imaging, LPS: lumboperitoneal shunt, VPS: ventriculoperitoneal shunt.
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F3
Postoperative MRI after a month demonstrated shrinkage of the cyst, and restoration of the cauda equina that was compressed from the outside of the dural sac (Fig. 3A and 3B).