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Abstract
Objectives
The aim of this study was to provide insight into idiopathic spinal cord herniation (ISCH) in terms of clinical presentation, pathophysiology, diagnosis, classification, and treatment.
Summary of Literature Review
ISCH is a rare disorder characterized by anterior displacement of the spinal cord through a ventral dural defect. It has increasingly been recognized and described over the past 10 years.
Results
ISCH occurs in middle-aged adults with a female preponderance. The most common clinical presentation is Brown-Sequard syndrome, which can progress to spastic paraparesis. Its pathophysiology is unknown. However, some authors proposed that inflammation may play an important role in the emergence of a dural defect. Magnetic resonance imaging typically shows an anterior kink of the thoracic spinal cord with an obliteration of the ventral subarachnoid space and the widened dorsal subarachnoid space. Surgery is generally recommended for patients with motor deficits or progressive neurological symptoms. The posterior approach has been used because it allows wide exposure of the spinal cord. The surgical treatment of ISCH consists of spinal cord reduction from the ventral dural defect, which can be managed with enlargement, direct repair, or duraplasty (dural repair with a patch). In recent years, duraplasty has been used more frequently than enlargement of the dural defect.
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Fig. 1.
The arachnoid membrane in a ventral dural defect is herniated and cerebrospinal fluid moves freely in and out of the defect. (A) An extradural arachnoid cyst is present. (B) The opening of the dural defect is blocked by the spinal cord. An adhesion between the spinal cord and arachnoid is found at the edge of the dural defect. (C) The spinal cord is herniated through the dural defect. There is a possibility of cord tethering, strangulation, incarceration, and ischemia.
Fig. 2.
Idiopathic spinal cord herniation in a 43-year-old man. He had a tingling sensation in his left leg for 3 years. (A, B) T2-weighted MRI and (C, D) a CT myelogram show anterior displacement of the spinal cord with an obliteration of the ventral subarachnoid space and an enlarged dorsal subarachnoid space at T2-3. There were CSF flow artifacts in the dorsal subarachnoid space in MRI (A, B) and no blockage of free-flowing contrast agent on the CT myelogram (C, D). MRI, magnetic resonance imaging; CT, computed tomography.
Fig. 3.
Intradural arachnoid cyst in a 37-year-old woman. She experienced weakness in the lower extremities. (A, B) T2-weighted MRI shows anterior displacement of the spinal cord with a widened subarachnoid space at T2-3. There was no cerebrospinal fluid flow artifact in the dorsal subarachnoid space, and the spinal cord was compressed by an intradural arachnoid cyst. MRI, magnetic resonance imaging.
Fig. 4.
(A) A ventral dural defect in the inner dura of the duplicated anterior dura. (B) The spinal cord is herniated through the dural defect and is ultimately constricted. (C) The spinal cord is released by enlargement of the defect.
Fig. 5.
Surgical procedure of duraplasty. (A) After dural opening, the dentate ligaments can be found. (B) The dentate ligaments are cut, which enables free mobilization of the spinal cord. The edge of the ventral dural defect is then confirmed. (C) The spinal cord is gently reduced inside the dura, and a patch is inserted and slid into the ventral side of the spinal cord. (D) Both ends of the patch are trimmed and sutured on the dural edge.
Table 1.
Different findings in imaging studies between idiopathic spinal cord herniation (ISCH) and intradural arachnoid cyst (IDAC)
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