Shunt to drain brain fluid

My wife had an shunt (pipe) installed into her dura mater which became blocked due to a blood vessel that burst in her brain. This happened four years ago. She had no trouble what so ever after the brain operation where 4 berries was closed. Suddenly she stared getting very severe headaches. We are very far from professional health care and are afraid that the shunt could became blocked and does not release enough fluid.  Is this possible. does a shunt block and as a layman how can I determine if it is blocked. According to the brain surgeon who did her operation the dura mater will be permanently blocked, Is that true or will it heal and allow fluid through
Please inform us urgently My wife's age 68 years further good health a bit overweight but not severe very low normal blood pressure 90/64 reasonably active.
Pieter & Allen

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Here are some typical symptoms according a website:
:
"It is important to appreciate that the presentation of shunt blockage can be extremely variable, both in terms of symptoms and speed of onset. The following are “typical” presenting symptoms:

Drowsiness
Headache
Vomiting
Irritability

Less common presentations include seizures, abdominal swelling (due to malabsorption of CSF by the peritoneum or encysting of CSF in the peritoneal cavity), cranial nerve palsies (particularly in the spina bifida child). The time course of shunt blockage may be more protracted and manifest in the form of chronic headache, cognitive decline and developmental standstill."