A rare cause of CSF shunt “failure” in a patient with NPH

An 80-year-old male presented with a 12-month history of gait disturbance, urinary incontinence and memory impairment. On admission, he showed no motor or sensory disturbance. His tandem gait was uncertain with enlarged base, deep tendon reflexes were symmetric, plantar cutaneous reflex was in flexion. A head MRI-scan revealed diffuse leukoencephalopathy, with signs of a previous left parietal ictus cerebri and an enlargement of supratentorial ventricles (Evan’s ratio 0.6) associated with narrowed CSF spaces at convexity. Neuropsycological evaluation revealed frontal and subcortical deficits, with impaired attention, executive slowing and visuospatial dysfunction. Katzmann intraventricular infusion test showed an alteration of CSF dynamics [1]. Patient underwent ventriculo-peritoneal shunt. Postoperatory course was uneventful, with a mild gait and cognitive improvement. Three months after discharge, patient presented cervical pain, progressive gait worsening and right brachio-crural palsy. Neurological examination showed the presence of an asymmetry of deep tendon reflexes, with right hyperreflexia and the presence of a right brachio-crural palsy (strength 3/5). Brain MRI showed a slight reduction of Evan’s ratio (0.5). Spinal cord MRI displayed a right ventral extra-axial mass located in the spinal canal, compressing the spinal cord at C2 level. Motor evoked potentials suggested suffering of central motor pathways. Gross total tumor removal was performed (Histological diagnosis: meningioma-WHO grade I) (Fig. 1). At 2-year follow-up, a significant improvement of the right paresis was observed. In the literature, reports exist about spinal tumors causing high-pressure hydrocephalus [2]. A widely accepted hypothesis is that protein overproduction can lead to a high CSF viscosity thus causing an increased resistance to its absorption, resulting in hydrocephalus [3]. Some authors detected an increased level of fibrinogen in CSF due to various mechanisms. Deposit of fibrinogen and its conversion to fibrin at the level of the subarachnoid spaces induces arachnoiditis and fibrosis, causing obstruction of CSF outflow [3]. Malignant tumors can also produce metastatic arachnoiditis by dissemination through the subarachnoid space. Moreover, hydrocephalus can occur in cervical tumors with high rostral cysts producing thickening of the leptomeninges at the cervico-medullary junction [4]. Koshu et al. described a patient showing ventriculomegaly associated with signs of increased intracranial pressure; after shunting, patient presented acute spinal cord signs and neurological deterioration [5]. Patient was diagnosed to harbor a cervical tumor. In that case, the authors hypothesized an almost complete obstruction of CSF circulation at cervical level due to the tumor. Shunt placement caused a significant decrease in subarachnoid space pressure above the tumor level with resulting dissociation of CSF pressure between above and below the tumor level which caused an upward herniation of the spinal cord below tumor level. As a result, a further decrease in subarachnoid space above the tumor was considered responsible of neurological signs. In all the reported cases, patients presented with clinical and radiological signs of acute hydrocephalus. In our case, instead, clinical history, neurological examination and brain imaging before surgery were all in favor of the diagnosis of INPH; no signs of intracranial hypertension or spinal cord compression were evident. In particular, patient neither presented signs of P. De Bonis P. P. Mattogno (&) G. Capone A. Mangiola C. Anile Institute of Neurosurgery, Catholic University School of Medicine, l.go F. Vito, 1, 00168 Rome, Italy e-mail: pierpaolo.mattogno@gmail.com