Syringomyelia as a presenting feature of shunt dysfunction: Implications for the pathogenesis of syringomyelia
A 33 years old female noted abnormal sensations in her left upper limb of two months duration. She was evaluated by neurologists and was believed to have psychiatric illness. She was then referred to a psychiatrist and was treated for somatoform disorder for two years when she complained of worsening of sensory disturbances in the form of sensory loss in a “cape-like” distribution along with painless ulcers in the left hand. At this time, the imaging of the cervical spine was done and she was found to have chiari I malformation and syringomyelia. She was later referred to neurosurgery for further management. On admission to neurosurgery department, she had normal optic fundi, sensory impairment from C4 to T8 on the left side with small, trophic ulcers in the left hand. Her left hand grip was weak. MRI examination revealed panventricular hydrocephalus with chiari I malformation along with syringomyelia extending from C1 to lower thoracic region. There was evidence of communication of fourth ventricle with the syrinx [Figure and ]. The patient underwent a right ventriculoperitoneal shunt. Following shunt insertion, there was no change in the patient's neurological status. CT scan showed decompression of the supratentorial ventricles with persistent dilatation of the fourth ventricle [] and hence, the patient underwent foramen magnum decompression and intradural exploration. An upper cervical laminectomy was also done for a possible syringopleural shunt, if necessary. During intradural exploration, an arachnoid veil was found to be covering the foramen of Magendie. The arachnoid veil was opened which revealed a gush of CSF. Following this the cervical cord size was found to decrease intraopertively and hence the planned syringopleural shunt was not done. Following foramen magnum decompression, the patient's neurological status improved with significant improvement in sensations and healing of trophic ulcers. Two months after surgery, she went back to work as a school teacher. Follow up MRI revealed collapse of the syrinx and decompression of ventricular system. However, interestingly, a thin streak of CSF representing the central canal was found extending from upper cervical to lower thoracic regions [Figures and ]. This was found to be consistent with the MRI appearance of the central canal as described by Holly and Batzdorf[] and Petit-Lacour et al.[] Five months later, she presented with a one week history of difficulty in walking and diminished sensations over the left upper limb and left side of the trunk. There was no history of headache, vomiting or transient obscurations of vision suggestive of shunt dysfunction. Examination at this time revealed normal optic fundi, diminished sensations from C2 to T8 on the left side, Grade 4/5 power in lower limbs, exaggerated knee and ankle jerks and bilateral upgoing plantars. Her shunt was found to be nonfunctional. MRI at this time revealed pan ventricular hydrocephalus with the fourth ventricle communicating with the holocord syrinx [Figure and ]. Patient underwent a revision of the ventriculoperitoneal shunt with gradual resolution of symptoms.