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.