Discussion
Normal pressure hydrocephalus is a cause of potentially reversible dementia. In 2019, an old man was referred to our hospital with classic triad of NPH. Serial CSF removals led to dramatic improvement in symptoms. The emergence of COVID-19 pandemic has stopped the planned treatment program. Meanwhile, a “miracle” event of spontaneous CSF leakage occurred which led to gradual improvement in cognitive and gait profiles.
Cerebrospinal fluid leakage have been classified into traumatic and spontaneous by Ommaya et al at 1968 (2). The “spontaneous” is applied to indicate that the leakage is not an immediate or delayed result of trauma. Interestingly, their article had other amassing features including a comprehensive diagram contains subdivisions for nontraumatic CSF rhinorrhea (2). In this regard, nontraumatic CSF leakage can be categorized into high-pressure and normal-pressure leaks. Hydrocephalus, either obstructive or communicating, was classified as a type of high-pressure CSF leakage (2). In 1978 , Oblu classified the different causes of nontraumatic CSF leak into four groups: congenital, tumoral, infectious and vascular. Hydrocephalus may be classified under the group of congenital (i.e. congenital stenosis of aqueduct of Sylvius) or tumoral (i.e. indirect effect of tumor by providing intracranial hypertension) (3).
In the published literatures, several cases with sudden leakage of CSF have been reported. In most of these cases, there is an evidence of raised intracranial pressure. For instance, there are some reports of choroid plexus papilloma (6, 7), colloid cyst of third ventricle (8), and Idiopathic Intracranial Hypertension (IIH) (9). Yang et al. collected 21 patients with spontaneous CSF rhinorrhea whose mean preoperative CSF pressure was 17.6 cmH2O. Surprisingly, all of the patients had increased postoperative ICP with mean ICP of 25.5 cmH2O (range from 21 to 32 cmH2O) (9). Schlosser et al. had performed postoperative lumbar puncture in ten patients with spontaneous CSF leak that all of them had elevated ICP (mean: 26.5 cmH2O) (10). In the same way, the CSF pressure was slightly elevated in our patient. To our knowledge, it is the first case of NPH reported with spontaneous CSF leakage. Interestingly, this event was associated with marked improvement in clinical features. There are some reports of spontaneous CSF leakage secondary to aqueductal stenosis (4, 5). Satyarthee reported a 16-yers old girl with headache, vomiting and chronic CSF rhinorrhea. She had an obstructive hydrocephalus due to aqueductal stenosis and underwent a ventriculo-peritoneal shunt surgery, but the CSF rhinorrhea persisted despite functional shunt and need to surgical repair (5). In contrast, Muzumdar et al. reported a 30-year-old male with 9-monthd history of CSF rhinorrhea as a result of aqueductal stenosis who had favorable response to shunting (4). The authors claimed that the fragile anatomy of cribriform plate and daily variations of CSF pressure might be a contributing factor for spontaneous CSF rhinorrhea in a patient with aqueductal stenosis. Alongside, any causes of transient rising of intracranial pressure (ICP) may open forcibly an occult anatomical dural defect and led to CSF leak (4). Sudden sneezing, coughing or Valsalva maneuver may have a similar mechanism for CSF leak. As the same way, our patient reported several times of sneezing prior to emergence of CSF rhinorrhea. Beside of these physiologic factors, we assume that daily variations of intracranial pressure may also a contributing factor in transient increment of ICP that consequently lead to spontaneous CSF leak. This was evident in two out of four times of measuring CSF opening pressure in our patient.
The interesting point of this case was the marked improvement of gait and cognition after spontaneous CSF leakage. It has been reported that the symptoms of IIH may improve after spontaneous CSF leakage. In the study of Yang et al., 18 out of 21 patients had presented with symptoms of IIH that disappeared after occurrence of spontaneous CSF rhinorrhea (9). In this clinical feature, the possible mechanism is sudden decrement of CSF pressure. Weather this mechanism can also explain the improvement of gait and cognition in NPH, is not clear.
Non-traumatic spontaneous CSF leakage may occur in the context of high or normal intracranial pressure. We report a patient suffered from NPH who had spontaneous CSF rhinorrhea that led to marked improvement in gait and cognitive function.