What strange and rare diseases lurk within neurology?

Neurologist spend most of their time treating many ‘mainstream’ disorders such as epilepsy and migraine. I discussed this in my previous post, what are the most iconic neurological disorders? Neurologists are however required to know many other diseases, often very rare and occasionally esoteric. Some of these diseases are so rare many neurologists haven’t heard of them, or only know about them in passing.

Human brain illustrated with millions of small nerves. Ars Electronica on Flikr. https://www.flickr.com/photos/arselectronica/13994747444
Human brain illustrated with millions of small nerves. Ars Electronica on Flikr. https://www.flickr.com/photos/arselectronica/13994747444


These rare diseases often  creep up on us unawares. It is difficult, if not impossible, for any neurologist to confidently diagnose, investigate, treat, and monitor these rare diseases without digging deep and researching extensively. What are these rare disorders? To find out, I scoured neurochecklists and compiled this list. I have linked each to a reference for further study. Here then are my 75 rarest and strangest neurological diseases


 17q deletion syndrome 

4H Syndrome

Alpers syndrome

Adult polyglucosan body disease

Alexander disease


Benign hereditary chorea

Barth syndrome

Biotin responsive basal ganglia disease

Brown-Vialetto Von-Laere (BVVL) syndrome

Brody disease


Calsequestrin storage myopathy

Coffin Lowry syndrome 

Congenital cataracts facial dysmorphism neuropathy (CCFDN)

Curranino syndrome


CANVAS syndrome

Cerebrotendinous xanthomatosis (CTX)


Danon disease

Doose syndrome

Dentatorubral pallidolyusian atrophy (DRPLA)


Facial onset sensory and motor neuronopathy (FOSMN)

Fatal familial insomnia (FFI)

Fragile X tremor ataxia syndrome (FXTAS)

Generalized epilepsy with febrile seizures plus (GEFS+)

Gerstmann Straussler Scheinker (GSS) syndrome

Hemiconvulsion hemiplegia (HH) syndrome

Hereditary myopathy with early respiratory failure (HMERF)

Jeavon’s syndrome (eyelid myoclonia with absences)

Joubert syndrome

Kufor Rakeb


Landau Kleffner syndrome

Lafora body disease

Menke’s disease

Miller Dieker syndrome


Myofibrillar myopathy

Melkersson Rosenthal syndrome

Nasu Hakola disease

Nemaline myopathy

Neuronal ceroid lipofuscinosis (NCL)

Neuro Sweet syndrome

Brian v.2. Amy Leonard on Flikr. https://www.flickr.com/photos/amyleonard/876151372
Brian v.2. Amy Leonard on Flikr. https://www.flickr.com/photos/amyleonard/876151372



Ornithine transcarbamylase (OTC) deficiency

Ohtahara syndrome

Panayiotopoulos syndrome (PS) 

Pantethonate kinase associated neurodegeneration (PKAN)

Perry syndrome

Potassium aggravated myotonias

Progressive encephalomyelitis rigidity and myoclonus (PERM)

Pyridoxine-responsive epileptic encephalopathy

Pelizaeus Marzbacher disease 

PHARC syndrome

Pourfour du petit syndrome


Rapid onset dystonia parkinsonism (RDP)

Refsum’s disease

Rippling muscle disease (RMD)

Raeder’s paratrigeminal syndrome

Rett syndrome


Sandhoff disease

Satoyoshi syndrome

Schwartz Jampel syndrome

Sepiapterin deficiency

SEPN-1 related myopathy 

Sialic acid storage diseases

Sjogren Larsson syndrome



Tangier disease

Tarui disease

Tyrosine hydroxylase deficiency (THD)

Unverricht Lundborg disease

Vici syndrome

Wolf Hirschhorn syndrome

Woodhouse Sakati syndrome

Zellweger syndrome


Arteries of the brain. Adrigu on Flikr https://www.flickr.com/photos/97793800@N00/7071077223
Arteries of the brain. Adrigu on Flikr https://www.flickr.com/photos/97793800@N00/7071077223



PS1. If you are a loyal follower of the blog, you would have realised that I have discussed this topic previously as the most perplexing diseases that excite neurologists. I hope you have found the alphabetical order here more helpful.

PS2. Do you have a rare or strange disease not listed here? Please leave a comment.

PS3. Why not try Neurochecklists for  the simplified, hands-on approach to these and other unusual neurological diseases.

Neurochecklists image

What is the relationship of MND and cancer?

There are many sources of neurology information, as I listed in my previous post titled what are the most reliable neurology reference sources? These sources let us know what is in and what is out; what is breaking and what has gone stale. Keeping on top of the ever-shifting information the journals churn out is challenging, but interesting. This information is the life blood of The Neurology Lounge, and keeps neurochecklists current and reliable.

Reference tracker icon. Berto on Flikr. https://www.flickr.com/photos/bertop/2485992973
Reference tracker icon. Berto on Flikr. https://www.flickr.com/photos/bertop/2485992973

In the task of keeping level with neurological developments, I first go to the journal Neurology, one of the clear leaders of the pack. Check it out on twitter under its handle, @GreenJournal. Browsing through a recent issue, I  was struck by a paper titled Population-based risks for cancer in patients with ALS. The authors of this paper report that people with motor neurone disease (MND) appear to be protected from developing many cancers, including the notorious lung cancer. In contrast, they are at a higher risk of testicular and salivary gland cancer.


Curious to know more, I looked for previous reports on this topic but I came out not any wiser. Older research have given conflicting results on the links between MND and cancer. Take this paper published in the International Journal of Cancer titled The risk of amyotrophic lateral sclerosis after cancer in U.S. elderly adults: a population-based prospective study. This found no links at all, as did another paper published in Journal of Neurology titled Prior medical conditions and the risk of amyotrophic lateral sclerosis. On the other hand, other researchers found that people with MND were at a higher risk of cancer. An example is this paper titled The association between cancer and amyotrophic lateral sclerosis, published in Cancer Causes and Control. This reported a link between MND and melanoma, and with tongue cancer. The bulk of the research before now however suggests that there is no link. Take this paper published in Amyotrophic Lateral Sclerosis & Frontotemporal Degeneration, and titled Amyotrophic lateral sclerosis and cancer: a register-based study in Sweden; the authors, led by Ammar al Chalabi, sounded an authoritative ring of finality when they said “our results provide no evidence for comorbidity of cancer and ALS“. Before now, that is!


So, is the latest study bucking the trend? Does MND really protect against some cancers and predispose to others? What does this all mean for people with MND? Or is all this just a quirk of the statistics? Questions, questions. I suspect this paper has just re-opened a can of worms, and more studies will surely follow. And they will refute and confirm the findings in equal measure.


For now, MND remains an enigma. You may explore it a bit more in my previous blog posts on the subject…and leave your thoughts behind in the comments box.


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.


What are other neurology blogs talking about?

I try to keep an eye on other neurology bloggers tapping away at their blogs. I previously listed the top neurology blogs in my posts, what is the state of neurology on the blogoshpere? and later updated the list of neurology blogs. What are these bloggers up to? Here are 5 interesting posts to give a taste.

1. From: Neuroskeptik


There was a recent, very concerning report about the reliability of functional MRI (fMRI) software. This raised doubts about the veracity of all fMRI research carried out over decades. Thankfully Neuroskeptic addressed this issue headlong in a post titled False positive functional MRI hits the mainstreamThe blog pointed out that fMRi software concerns are not new, and importantly, they are not serious enough to invalidate 15 years of research. Phew! The post also discussed the retraction and anti-retraction story that somehow missed the headlines. And who is Neuroskeptic? You need to check out another blog on pseudnymous bloggers to find out.

2. From: Brainfacts.org


What could be more tantalising than a blog post titled The neuroscience of violence? This post, by Douglas Fields, discusses the discovery of the neuronal rage circuit, and how neuroscientists can now manipulate this. The post says “…with the flip of a switch neuroscientists can launch an animal into a violent attack or arrest a violent battle underway by activating or quelling the firing of specific neurons in the brain’s rage circuits”. Add the hypothalamic attack region to the mix and you have a blog post worth reading. 

3. From: The Stroke Blog


I admit that the question, What does “blurry vision” really mean after stroke?, has never occurred to me. This clinical post is a good reminder of all the visual symptoms that may accompany a stroke. It is quite basic but informative.

4. From: Curious Stardust


I was intrigued by this blog post by Seana Coulson titled What a Speech Disorder Reveals About Brain Function. It looks at language and its relationship to the brain and takes readers on a historical excursion of the ‘discovery’ of aphasia by Paul Broca. It details how the field has progressed since then, and sprinkled a couple of demonstrative video clips to explain the symptom. The blog refreshingly admits to how little we know about the brain: while cognitive neuroscientists have learned quite a bit in the last 150 years about which parts of the brain are involved in different aspects of speaking and understanding language, we still don’t have a really good explanation of exactly what the cells in the left frontal lobe code for…”. Will we ever?

5. From: Beyond the Ion Channel


Neurogenetics isn’t easy but this blog makes it, at least, readable. Take this post by titled RORB in generalized epilepsy with absences–going retinoic. This explores a hormone receptor called Retinoid-Related Orphan Receptor-Beta (RORB) which plays an important role in epilepsy and neuro-developmental disorders. Not the easiest read for a layperson, but a good read anyway. 

Suzanne Valadon Blogging, after Lautrec. Mike Licht on Flikr. https://www.flickr.com/photos/notionscapital/4784971557
Suzanne Valadon Blogging, after Lautrec. Mike Licht on Flikr. https://www.flickr.com/photos/notionscapital/4784971557

Are you blogging neurology? Please drop a comment… and a link to your blog.