Miyazaki Syndrome as a Complication of Shunt Drainage

A 41-year-old female was referred to the neurosurgery outpatient clinic with progressive bipyramidal syndrome. Medical history included premature birth and prior intraventricular hemorrhage with hydrocephalus. Ventricular-peritoneal (VP) shunting was performed in the management of hydrocephalus. However, complications related to over-drainage, along with hyperostosis of the skull and craniosynostosis, caused scaphocephaly.

Over the course of several months, she experienced progressive difficulties walking and developed right-sided weakness. Neurological examination revealed right-sided hemiparesis, hyperreflexia, and bilateral Babinski's sign. Imaging of the brain and cervical spine (Fig 1) showed scaphocephaly with slit-like ventricles and myelopathy extending from the C1 to C3 levels, along with the presence of spinal epidural venous engorgement. In the absence of a diagnosis, she was placed under long-term follow-up care by her neurologist. Follow-up magnetic resonance imaging (MRI) of the cervical spine revealed progressive myelopathy, before the diagnosis of Miyazaki syndrome was made. She underwent VP-shunt revision, with implantation of a Miethke proGAV 2.0 0-20/20 (programmable valve pressure setting 8). Outpatient clinic follow-up at 6 months showed stabilization of the bipyramidal symptoms. Follow-up MRI showed improvement of the epidural venous engorgement.

Miyazaki syndrome arises as a complication of cerebrospinal fluid (CSF) hypotension caused by excessive drainage through VP-shunting. Although CSF hypotension is often associated with well-known symptoms, like orthostatic headache and cranial nerve palsies, the development of epidural venous engorgement leading to spinal cord compression is a less common but critical manifestation.

The syndrome is characterized by cervical myelopathy or radiculopathy due to cervical epidural venous congestion, results from complex pathophysiological mechanisms.^{1, 2} These include changes in CSF pressure, consistent with the Monro-Kellie doctrine, and dysfunction in the Starling resistor, leading to the enlargement and dilation of the spinal epidural venous plexus.¹ Venous congestion can lead to spinal cord or nerve roots compression or circulation hampering,¹ causing neurological symptoms, whereas presenting a unique diagnostic challenge. One of the striking features of Miyazaki syndrome is that it can manifest without the typical symptom of orthostatic headache, which is commonly associated with CSF hypotension. Instead, patients with Miyazaki syndrome may develop myelopathy symptoms slowly over time, making it challenging to diagnose, potentially leading to misdiagnosis.³ This underlines the importance of considering Miyazaki syndrome in the differential diagnosis of patients with VP-shunts who present with myelopathy but do not experience headaches. Timely recognition is crucial and diagnostic imaging, particularly brain and spine MRI with a focus on venous blood flow, is required to confirm the diagnosis of Miyazaki syndrome. Swelling of the cervical venous plexus, even in the absence of other typical hypotension images, can be a key indicator of the syndrome.³

Treatment for Miyazaki syndrome primarily aims to address CSF over-drainage. Possible interventions include adjusting the opening pressure of the valve system, inserting a programmable valve, if needed, or closing/removing the shunt altogether. Once the diagnosis of Miyazaki syndrome is established, revision of the shunt and antisiphon system can significantly reduce morphological changes and improve the patient's symptoms and quality of life.^1-3

In summary, this case highlights the clinical importance of understanding Miyazaki syndrome, a rare but potentially debilitating complication of CSF over-drainage through VP-shunts, and emphasizes the significance of early diagnosis and appropriate treatment to improve patient outcomes.

R.H.G.J.vL., J.vA., and M.P.TL-P contributed to conception and design of the study; R.H.G.J.vL. contributed to drafting the text and preparing the figures; R.H.G.J.vL. and M.P.TL-P contributed to the acquisition and analysis of data.

Nothing to report.