What are the pitfalls and perils of intracranial pressure?

Crudely speaking, the nervous system is made up of two parts. The peripheral nervous system, composed of nerves and muscles, is rather robust and roams free, exposed to the elements. On the other hand, the central nervous system, consisting of the brain and spinal cord, is delicate and fragile. It is therefore protectively cocooned in a rigid skull and a hardy vertebral skeleton. But even this tough fortress isn’t secure enough for these dainty neurones; they are, after all, the command and control system for the whole body. Therefore, to further insulate them from the physical and physiological perturbations that continuously threaten them, nature has further sequestered them within a very exquisitely regulated irrigation system, the cerebrospinal fluid (CSF).

Internet Archive book Images on Flickr. https://www.flickr.com/photos/internetarchivebookimages/14769907251/

The CSF is actually a fine filtrate of the blood that flows in the arteries. The sieve is the very forbidding blood-brain barrier (BBB) which turns away all the blood cells, and carefully sets a target on how much protein and glucose to let in. The pressure within the CSF is also very finely tuned, not too high…and not too low; that is how the neurones like it.


By Dr. Johannes Sobotta – Atlas and Text-book of Human Anatomy Volume III Vascular System, Lymphatic system, Nervous system and Sense Organs, Public Domain, https://commons.wikimedia.org/w/index.php?curid=29135482


Alas, as with all systems, the CSF is vulnerable to external miscreants; infections such as meningitis,  encephalitis, and brain abscesses which cause brain swelling or cerebral edema. The CSF is also largely defenceless to internal insurgents, fifth columnists, such as a brain tumours, haematomas (bleeds), and cerebral vein thrombosis (venous clots). The smooth flow of the CSF may also be obstructed, resulting in hydrocephalus or enlargement of the brain’s ventricular system. In all these circumstances, the intracranial pressure is often elevated, a situation aptly dubbed intracranial hypertension. Very often, intracranial hypertension may occur without any obvious cause, and this condition is referred to as idiopathic intracranial hypertension (IIH). Because IIH threatens vision, neurologists have abandoned its old and misleading name, benign intracranial hypertension (BIH).

By BruceBlaus. When using this image in external sources it can be cited as:Blausen.com staff (2014). “Medical gallery of Blausen Medical 2014“. WikiJournal of Medicine 1 (2). DOI:10.15347/wjm/2014.010. ISSN 2002-4436. – Own work, CC BY 3.0, Link

Intracranial hypertension is no walk in the park as it portends disaster, whatever its cause. As it is a  potentially fatal state, the early warning signs are drilled into all doctors in medical school…when their brains are still malleable. These red flag features are severe headache, impaired consciousness, progressive visual loss, dilated or blown pupils, papilledema (swelling of the optic nerve head), and neck stiffness. The standard operating procedure for intracranial hypertension is to deflate the pressure as quickly as possible, by hook or by crook. This may be medical, with infusions such as mannitol, or surgical, with procedures such as decompressive craniectomy (removal of part of the skull). The terminal stage of intracranial hypertension, the most ominous neurological emergency, is cerebral herniation: this is the catastrophic compression of the brainstem into the narrow and tight spinal canal: a physical state that is incompatible with life.

By Ambika S., Arjundas D., Noronha V. – https://openi.nlm.nih.gov/detailedresult.php?img=2859586_AIAN-13-37-g001&query=papilledema&it=xg&req=4&npos=2, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=47658492

As with all waves, intracranial pressure also has its lows, and it is a no-brainer that neurologists call this intracranial hypotension. This is not as hazardous as intracranial hypertension, but it is worthy of respect in view of its devastating morbidity. The usual cause, and again no prizes for guessing this, is a leak. The puncture in this case is often iatrogenic, in other words, the whodunnit is the doctor. This may be deliberate, such as when the doctor attempts to remove some CSF to test, via a procedure called a  lumbar puncture (LP). It may also be accidental, such as when your friendly anaesthetist performs an epidural to relieve pain. In both situations, the dura protecting the CSF is perforated, causing spinal fluid leakage. This manifests as postural or orthostatic headache; by definition, this is a headache that sets in within 15 minutes of standing up, and resolves within 15 minutes of lying down flat. The treatment in such cases is strict bed rest, drinking loads of fluids, including caffeinated drinks, and waiting for the dura to heal itself…usually within one week. If this does not happen, then an intravenous caffeine infusion may be required. An epidural blood patch may also be carried out, again by your friendly anaesthetist, who squirts a little of the victims blood around the site of the leak, to, well, ‘patch it up’. In extremis, surgery may be needed to seal the leak, but this is way beyond my pay grade.

By Paul Anthony Stewart – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=75808444

Intracranial hypotension may however develop without any apparent cause, and this is called spontaneous intracranial hypotension (SIH). The causes of SIH include unpredictable dural tears, ruptured meningeal diveticuli (outpouchings of the dura), and direct CSF-venous fistulae (don’t ask!) There are a variety of risk factors for SIH such as connective tissue diseases and bariatric surgery. It is very helpful that SIH leaves characteristic tell-tale clues on brain MRI scans, and these include subdural hygroma (plain fluid collections under the dura); subdural haematoma (blood under the dura); meningeal enhancement with contrast dye; engorgement of the pons and pituitary; and the interesting dinosaur tail sign on fat suppression T2 MRI (FST2WI). The gold standard test to localise the site of leakage in SIH is radionuclide cisternography. In the absence of this rather sophisticated test, a CT myelogram may be considered. Treatment is similar to that of other forms of intracranial hypotension, but other measures that may be required to seal the leak, including the use of fibrin sealeant.

By Hellerhoff – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=18946727

If you have reached the end of this blog post, then you deserve a prize. Four prizes actually: recent interesting reports in the field of SIH to explore:

  1. The use of transorbital ultrasound in making a diagnosis.
  2. Treatment of complicated SIH with intrathecal saline infusion.
  3. SIH complicated by superficial siderosis.
  4. Severe SIH complicated by sagging brain causing causing postural loss of consciousness.
By © Nevit Dilmen, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=45660723



7 ominous signs that suggest you need to see a neurologist

Neurologists spend most of their time diagnosing benign conditions which are curable or treatable, or at least people learn to live with. Every now and then we see people with startling symptoms such as coma, convulsions, neck stiffness, or paralysis. These are obviously concerning to patients and their families who have a foreboding of diseases such as meningitis, epilepsy, and stroke. Serious as these disorders are, they at least announce themselves and show their hands. Many other neurological symptoms unfortunately give no hint of the serious diseases that follow in their trail. That is when things get a bit tricky.

Ominous. Ankakay on Flikr. https://www.flickr.com/photos/ankakay/4101391453
Ominous. Ankakay on Flikr. https://www.flickr.com/photos/ankakay/4101391453

What are these seemingly benign symptoms which jolt neurologists out of their blissful complacency? What are these red flag symptoms that pretend they are grey? Here are my 7 deceptively ominous neurological signs everyone should know about.

7. A numb chin

By Henry Vandyke Carter - Henry Gray (1918) Anatomy of the Human Body (See "Book" section below)Bartleby.com: Gray's Anatomy, Plate 784, Public Domain, https://commons.wikimedia.org/w/index.php?curid=531758
By Henry Vandyke CarterHenry Gray (1918) Anatomy of the Human Body (See “Book” section below)Bartleby.com: Gray’s Anatomy, Plate 784, Public Domain, https://commons.wikimedia.org/w/index.php?curid=531758

This must be the most deceptive sinister symptom in neurology. Not many people will rush to their doctors to complain about a numb chin, but it is a symptom that makes neurologists very nervous. This is because the chin gets its sensory supply from the mandibular branch of the fifth cranial nerve, also called the trigeminal nerve because it has three branches. And neurologists know that, for some bizarre reason, cancers from other parts of the body occasionally send deposits to this nerve. The numb chin syndrome is therefore not to be treated lightly.

6. Muscle twitching

OK, don’t panic yet. We have all experienced this; a flickering of an overused and tired muscle; a twitching of the odd finger; the quivering of the calf muscles in older people. Neurologists call these fasciculations, and they are only a concern if they are persistent, progressive, and widespread. And also usually only if the affected muscles are weak. In such cases neurologists worry that fasciculations are the harbingers of sinister diseases, particularly motor neurone disease (MND), better known in America as amyotrophic lateral sclerosis (ALS) or Lou Gehrig disease. Many people with muscle twitching will however have nothing seriously wrong with them, and many will be shooed out of the consulting room with the label of benign fasciculations syndrome (we love our syndromes, especially when they are benign). There are many other causes of fasciculations, but MND is clearly the most sinister of them all.

5. Transient visual loss

Scott Maxwell on freestockphotos. http://www.freestockphotos.biz/stockphoto/9747
Scott Maxwell on freestockphotos. http://www.freestockphotos.biz/stockphoto/9747

Neurologists often ask people with headache if their vision blurs or disappears for brief periods of time. These visual obscurations are not as dramatic as the visual loss that accompanies minor strokes or transient ischaemic attacks (TIAs). Visual obscurations affect both eyes and last only a few seconds. They are the result of sudden but brief increases in an already elevated pressure in the head. This may occur with relatively benign conditions such as idiopathic intracranial hypertension (IIH), but it may also portend a serious disorder such as a brain tumour.

4. Sudden loss of bowel or bladder control


Loss of control down there would surely concern many people, but often not with the urgency it deserves. There are many non-neurological causes of bowel or bladder incontinence, but a sudden onset suggests that it is arising from the nervous system. The worrying diagnoses here are spinal cord compression and spinal cord inflammation (transverse myelitis). These disorders are often associated with other symptoms such as leg stiffness and weakness, but I really wouldn’t wait until these set in before I ask to see a neurologist.

3. Saddle anaesthesia


Whilst we are on the topic of things down there, a related sinister symptom is loss of sensation around the genitals and buttocks, something your doctor will prudently call saddle anaesthesia. This arises when the nerves coming off the lower end of the spinal cord, collectively called the cauda equina, are compressed. The unpalatable condition, cauda equina syndrome (CES), worries neurologists because the compression may be due to a tumour in the spinal canal.

PS: The bicycle saddle is an apt analogy, but if you prefer horse riding, below is an alternative image to soothe your hurt feelings.


By BLW - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=1956552
By BLW – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=1956552

2. A painful droopy eyelid

A droopy eyelid is a deceptively benign symptom which worries neurologists. This symptom, which neurologist prefer to call ptosis, is particularly concerning if it is accompanied by double vision. One worrying disorder which causes ptosis is myasthenia gravis (MG), and this presents with ptosis on both sides. More sinister is ptosis which is present only on one side, particularly if it is painful. This may be caused by brain aneurysms, especially those arising from a weakness of the posterior communicating artery (PCOM) artery. As the aneurysm grows, it presses on the third cranial or oculomotor nerve, one of three nerves that controls the eyeballs and keeps the eyelids open. An aneurysm is literally a time-bomb in the brain as they wield the threat of bursting and causing a catastrophic bleeding around the brain. This makes ptosis an ominous, but also a helpful, neurological symptom.

By Cumulus z niderlandzkiej Wikipedii, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=3167579
By Cumulus z niderlandzkiej Wikipedii, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=3167579

There are many other causes of ptosis including Horner’s syndrome, so don’t panic yet but get that eyelid checked out if it refuses to straighten out.


1. Thunderclap headache

By © Marie-Lan Nguyen / Wikimedia Commons, CC BY 2.5, https://commons.wikimedia.org/w/index.php?curid=24189896
By © Marie-Lan Nguyen / Wikimedia Commons, CC BY 2.5, https://commons.wikimedia.org/w/index.php?curid=24189896

thunderclap headache is a symptom that means exactly what it says on the label! Neurologists will ask if the onset felt as if one was hit by a cricket bat. Even though most people have never been so assaulted, almost everyone with thunderclap headache readily agree this is what it feels like. It is such a distressing symptom that it doesn’t strike the afflicted person (pun intended) that their doctors are more concerned about investigating them, then they are in curing their headache. They patient is rushed to the CT scanner, and then subjected to a lumbar puncture. The doctors then heave a huge sigh of relief when the spinal fluid shows no blood or blood products, reassured that the patient has not suffered a subarachnoid haemorrhage (SAH) from a ruptured a brain aneurysm. The patient, who now has just another headache, is left to get to grips with their now, suddenly, very uninteresting symptom. There are many other causes of a thunderclap headache, but a ruptured aneurysm is the most sinister. If you develop a thunderclap headache, don’t wait to see a neurologist…just get to the nearest hospital!

PS: Don’t feel aggrieved if you are across the Pacific; it is also a thunderclap headache if it felt like being hit by a baseball bat!

Baseball bat in sun. Peter Chen on Flikr https://www.flickr.com/photos/34858596@N02/3239696542
Baseball bat in sun. Peter Chen on Flikr https://www.flickr.com/photos/34858596@N02/3239696542


Want to check out more ominous signs? Check out Smart handles and red flags in neurological diagnosis by the neurologist Chris Hawkes in Hospital Medicine.


Maggots, viruses and lasers: some innovations for brain tumours

Brain tumours are among the most distressing of cancers, partly because of they arise from the most important body organ. Current treatment revolves around debulking surgery and palliative chemotherapy and radiotherapy. There are developments every day to improve the outcome of this awful cancer. Below are 5 things that may, or may not, lead to better brain tumour care


"Hermetiaillucens" by MD-Terraristik – Laut [1] ist Dennis Kress Mitinhaber des Unternehmens - www.MD-Terraristik.de. Licensed under Public Domain via Commons.
Hermetiaillucens” by MD-Terraristik – Laut [1] ist Dennis Kress Mitinhaber des Unternehmens – http://www.MD-Terraristik.de. Licensed under Public Domain via Commons.

I came across this interesting development in news headlines titled Maggot-Like Robot Eats Brain Tumors and Robot Maggots Feed On Brain Tumors. Unlike many sensational headlines, there appears to be some truth behind these ones. The National Institute of Biomedical Imaging and Bioengineering for example  suggests that, in future, robots may be used to target hard-to-reach brain tumours. The leading neurosurgeon in this endeavour is J Marc Simard of the University of Maryland. Maggot Bots indeed!


By Fixi at the German language Wikipedia, CC BY-SA 3.0, Link
By Fixi at the German language Wikipedia, CC BY-SA 3.0, Link

The dreaded poliovirus, after all the years of trying to eradicate it, seems to have some benefit after all. The virus may come in handy in the fight against the worst type of brain tumour, glioblastoma multiforme. Matthias Gromeier is leading the research in this field. It however has a long way to go, and this analysis in Forbes puts the progress in perspective.


"DNA methylation" by Christoph Bock (Max Planck Institute for Informatics) - Own work. Licensed under CC BY-SA 3.0 via Commons.
DNA methylation” by Christoph Bock (Max Planck Institute for Informatics)Own work. Licensed under CC BY-SA 3.0 via Commons.

The holy grail in tumour therapy is to target the treatment at the genetic level. This innovative approach to map the genetic picture of tumours is rather too technical for this blog, but you may explore the topic if you feel bold enough, by reading this article from the New England Journal of Medicine titled Glioma Groups Based on 1p/19q, IDH, and TERT Promoter Mutations in Tumors. Or perhaps the gentler read from Biotech in Asia titled Tailor-made treatment for brain tumor through genetic profiling.


1.2W Class 4 Very High Power Blue Laser, Dark Background. Andrew "FastLizard4" Adams on Flikr. https://www.flickr.com/photos/fastlizard4/5660747232
1.2W Class 4 Very High Power Blue Laser, Dark Background. Andrew “FastLizard4” Adams on Flikr. https://www.flickr.com/photos/fastlizard4/5660747232

As you may imagine, it is a challenge for the neurosurgeon to tell cancer cells apart from normal tumour cells during surgery. This therefore often leads to incomplete removal of the cancerous cells. The development of a laser probe that could help distinguish normal from abnormal cells is therefore welcome. The laser distinguishes normal from abnormal cells by the way they reflect light back to it. You may learn more about this in the BBC titled Laser detects brain tumour cells during surgery.


https://www.youtube.com/embed/MGNjtfizYTI” target=”_blank”>

The BBC link above is actually better than ‘good enough’ because it also makes reference to another innovation, the iknife or intelligent knife. This is ‘an electro-surgical scalpel that produces smoke as it cuts through tissue‘. The tissue is then quickly analysed to tell what type of tumour the surgeon is facing. The video clip above says it all.


Red Hot Coals Texture 2. Heath Alseike on Flikr. https://www.flickr.com/photos/99624358@N00/21314199361
Red Hot Coals Texture 2. Heath Alseike on Flikr. https://www.flickr.com/photos/99624358@N00/21314199361

Finally, this technique uses high temperatures to treat brain tumours. It is described as an ‘MRI-guided high-intensity laser probe that “cooks” cancer cells deep within the brain’. That says it all!

B0010383 Highly invasive human paediatric brain tumour derived cells. Wellcome Images on Flikr. https://www.flickr.com/photos/wellcomeimages/25821182694
B0010383 Highly invasive human paediatric brain tumour derived cells. Wellcome Images on Flikr. https://www.flickr.com/photos/wellcomeimages/25821182694

There is hope yet in the fight against one of natures worst cancers.