What features distinguish subarachnoid haemorrhage in people with polycystic kidneys?

Polycystic kidney disease among 4,436 intracranial aneurysm patients from a defined population

Nurmonen HJ, Huttunen T, Huttunen J, et al.

Neurology 2017; 89:1852-1859.



To define the association of autosomal dominant polycystic kidney disease (ADPKD) with the characteristics of aneurysmal subarachnoid hemorrhage (aSAH) and unruptured intracranial aneurysm (IA) disease.


We fused data from the Kuopio Intracranial Aneurysm database (n = 4,436 IA patients) and Finnish nationwide registries into a population-based series of 53 IA patients with ADPKD to compare the aneurysm- and patient-specific characteristics of IA disease in ADPKD and in the general IA population, and to identify risks for de novo IA formation.


In total, there were 33 patients with ADPKD with aSAH and 20 patients with ADPKD with unruptured IAs. The median size of ruptured IAs in ADPKD was significantly smaller than in the general population (6.00 vs 8.00 mm) and the proportion of small ruptured IAs was significantly higher (31% vs 18%). Median age at aSAH was 42.8 years, 10 years younger than in the general IA population. Multiple IAs were present in 45% of patients with ADPKD compared to 28% in the general IA population. Cumulative risk of de novo IA formation was 1.3% per patient-year (vs 0.2% in the general IA population). Hazard for de novo aneurysm formation was significantly elevated in patients with ADPKD (Cox regression hazard ratio 7.7, 95% confidence interval 2.8-20; p < 0.0005).


Subarachnoid hemorrhage occurs at younger age and from smaller intracranial aneuryms in patients with ADPKD and risk for de novo IAs is higher than in the general Eastern Finnish population. ADPKD should be considered as an indicator for long-term angiographic follow-up in patients with diagnosed IAs.

Cerebral aneurysms: risk factors for formation

Abstract link

By Tiago Etiene QueirozOwn work, CC BY-SA 3.0, Link

What are the 10 CT pitfalls of subarachnoid haemorrhage?

Pseudo-subarachnoid hemorrhage: a potential imaging pitfall

Lin CY, Lai PH, Fu JH, Wang PC, Pan HB.

Can Assoc Radiol J 2014; 65:225-231.



Increased density of the basal cisterns and subarachnoid spaces on computed tomographies (CT) is a characteristic finding of acute subarachnoid hemorrhage (SAH). Excluding head injury, SAH leads to the performance of angiographic studies to rule out vascular lesions. Thus, recognition of the radiologic feature of pseudo-SAH on CT is important to avoid unnecessary testing and treatment delay.


Several mimics of SAH have been reported:

  1. Diffuse cerebral oedema due to various causes
  2. Purulent meningitis
  3. Cerebral infarction
  4. Subdural hematoma (SDH)
  5. Leakage of intravenous contrast into the subarachnoid space
  6. Status epilepticus
  7. Intracranial hypotension
  8. Intrathecally administered contrast medium and
  9. Polycythemia

This pictorial essay presents the varied manifestation of radiologic mimics of SAH.

This paper is cited in the neurochecklist:

Subarachnoid haemorrhage (SAH): investigations

Article link

By James Heilman, MDOwn work, CC BY-SA 3.0, Link
Headaches Stroke

What are the distinctive features of headache in subarachnoid haemorrhage?

Distinguishing characteristics of headache in nontraumatic subarachnoid hemorrhage

Mac Grory B, Vu L, Cutting S, Marcolini E, Gottschalk C, Greer D.

Headache 2018; 58:364-370.



Subarachnoid hemorrhage (SAH) is a life-threatening emergency that is frequently missed due to its varied and often subtle presentation. The most common presentation of SAH is with a severe headache. The classical adjective used in SAH is “thunderclap”; however, this has not been well defined in the literature, rendering it a challenge to triage patients in clinical practice presenting with severe headache.


We undertook a prospective, observational study at a tertiary academic medical center examining the clinical characteristics of the presenting headache in SAH. We enrolled patients through the emergency department and from the neurosciences intensive care unit, and documented clinical features of the headache including the time to peak intensity, location, associated symptoms, and activities that caused worsening.


One hundred and fifty-eight subjects were enrolled, of whom 20 patients had SAH and 138 did not. Notable distinguishing features on history included occipital location (55% in the SAH group vs 22% in the non-SAH group, P < .001), “stabbing” quality (35% in the SAH group vs 5% in the non-SAH group, P < .001), presence of prior headache (50% in the SAH group vs 83% in the non-SAH group, P = .002), and associated meningismus (80% in the SAH group and 42% in the non-SAH group, P = .002). Sixty-five percent of patients with SAH reported that their headache peaked within 1 second of onset, compared with only 10% of those without SAH (P < .001).


This is the first study that has sought to examine in detail the clinical characteristics of the presenting headache in SAH. Our study suggests that the clinical features of headache with SAH are distinct from those associated with other headache syndromes, and that this may prove useful in the acute care setting in triaging patients with a chief complaint of headache.

This reference is cited in the neurochecklist:

Subarachnoid haemorrhage (SAH): clinical features

Abstract link

Thunder [Explored]. Walid Manfouhd on Flikr.
Neurological infections

The 7 most ruthless bacterial infections of the nervous system

This is a follow up to our previous post, the 7 most devastating viral neurological infections. The list of bacteria that invade the nervous system is endless, but some stand out because of the fear they evoke, and the peril they pose. Here then are the 7 most horrifying bacterial infections that threaten the nervous system.

1. Bacterial meningitis

Klebsiella pneumonia bacterium. NIAID on Flikr.

Many bacteria invade the covering of the brain, the meninges, without invading the brain substance. The commonest are Neisseria meningitidis, causing meningococcal meningitis, and Streptococcus pneumoniae, causing pneumococcal meningitis. Other relatively frequent meningeal intruders include Listeria monocytogenes and Haemophilus influenzae. Bacteria may get into the brain following infections elsewhere, such as sinusitis or otitis media (inner ear infection). There are many complications of bacterial meningitis such as cerebral venous thrombosis (CVT) and brain abscess.

2. Tuberculosis

Mycobacterium tuberculosis bacteria, the cause of TB. NIAID on Flikr.

Tuberculosis (TB) is probably as old as history. It is caused by mycobacterium tuberculosis, a slow groing but pernicious organism. TB spares no part of the nervous system, and manifests often as tuberculous meningitis (TBM) or Pott’s disease of the spine. Nervous system TB may also present as an encephalopathy, tuberculoma, brain abscess, vasculopathy, arachnoiditis, radiculomyelitis, and calvarial TB.

3. Neurosyphilis

ff treponema pallidum. isis335 on Flikr.

Treponema pallidum, the bacterium behind the dreaded syphilis, is another ancient bug. It has a variety of ways it terrorises the nervous system, and the longer it inhabits the neurones, the worse the outcome. Typical manifestations of neurosyphilis are tabes dorsalis, general paresis of the insane (GPI), taboparesis, stroke, meningovascular syphilis, optic neuritis (ON), and several movement disorders.

4. Lyme neuroborreliosis

Lyme Disease Bacteria, Borrelia Burgdoferri. NIAID on Flikr.

Lyme disease has acquired an infamy which is probably beyond its real notoriety. It is best known for its tick-borne transmission, and for its classical dermatological feature, erythema chronicum migrans. It affects the nervous system in diverse ways such as encephalomyelitislymphocytic meningitis, cranial neuropathies, spinal radiculitis, stroke, diaphragmatic paralysis, and peripheral neuropathy. Post-Lyme syndrome is a very contentious topic; you may read more on this in a post from our sister blog, The Neurology Lounge, titled ‘Why is chronic Lyme disease so frustrating to neurology.

5. Neurobrucellosis

By This media comes from the Centers for Disease Control and Prevention‘s Public Health Image Library (PHIL), with identification number #1902.Note: Not all PHIL images are public domain; be sure to check copyright status and credit authors and content providers.English | Slovenščina | +/−, Public Domain, Link

Neurobrucellosis is a rarely discussed bacterial infection but it is a significant contributor to neurological morbidity and mortality around the world. It is caused by various brucella species usually grouped under the name Brucella militensis. It has a long reach in the nervous system, causing  a variety of insults such as encephalitis, meningoencephalitis, cranial neuropathies, intracerebral haemorrhage (ICH), subarachnoid haemorrhage (SAH), transverse myelitis, radiculitis, and peripheral neuropathy.

6. Leprosy

Public Domain, Link

This most distasteful of infectious diseases unfortunately has a strong affinity for the nervous system. Unlike its distant cousin, TB, leprosy favours the peripheral over the central nervous system. Its hallmark is thickening of the nerves or nerve hypertrophy. Caused by Mycobacterium leprae, leprosy has a legion of neurological manifestations such as mononeuritis, mononeuritis multiplex, cranial and peripheral neuropathy, myelitis, and leprous ganglionitis.

7. Botulism

Clostridium botulinum. Phil Moyer on Flikr.

Botulism is the end result of damage by the toxin of Clostridium botulinum. This toxin produces a deadly paralysis by blocking neural transmission across the neuromuscular junction (NMJ). Botulinum toxin respects no borders, able to gain access to the nervous system through the gut, the skin, or the lungs. It paralyses everything, causing acute limb, ocular, and bulbar weakness. Left unchecked, botulism results in autonomic dysfunction and respiratory failure.


PS: For Tetanus, check out The Neurology Lounge blog post on The 13 most dreadful neurological disorders


Explore more neurological infections in neurochecklists!

Bacteria. AJ Cann on Flikr.

Does aspirin increase the risk of bleeding from cerebral aneurysms?

Aspirin and risk of subarachnoid hemorrhage: systematic review and meta-analysis

Phan K, Moore JM, Griessenauer CJ, Ogilvy CS, Thomas AJ.

Stroke 2017; 48:1210-1217.



Recent studies have suggested that the use of low-dose aspirin may reduce the risk of aneurysmal subarachnoid hemorrhage (aSAH). We aimed to evaluate any association between aspirin use and risk of aSAH based on the literature, and whether this is influenced by duration or frequency of aspirin use.


A search of electronic databases was done from inception to September 2016. For each study, data on risk of aSAH in aspirin versus nonaspirin users were used to generate odds ratios and 95% confidence intervals, and combined using inverse variance–weighted averages of logarithmic odds ratios in a random-effects models.


From 7 included studies, no significant difference was noted between aspirin use of any duration or frequency and nonaspirin users (odds ratio, 1.00; 95% confidence interval, 0.81–1.24; P=0.99). We found a significant association between short-term use of aspirin (<3 months) and the risk of aSAH (odds ratio, 1.61; 95% confidence interval, 1.20–2.18; P=0.002). No significant difference was found in terms of risk of aSAH for 3 to 12 months, 1 to 3 years, and >3 years of durations of use. No significant association was found between infrequent aspirin use (≤2× per week) or frequent use (≥3× per week) with risk of aSAH.


Current evidence suggests that short-term (<3 months) use of aspirin is associated with increased risk of aneurysmal subarachnoid haemorrhage. Limitations include substantial heterogenity of the included studies. The role of long-term aspirin in reducing risk of aSAH remains unclear and ideally should be addressed by an appropriately designed randomized controlled trial.

This abstract is cited in the neurochecklist:

Cerebral aneurysms: risk factors for rupture

Abstract link

By Hellerhoff – Own work, CC BY-SA 3.0,

Is the growth of cerebral aneurysms predictable?

ELAPSS score for prediction of risk of growth of unruptured intracranial aneurysms

Backes D, Rinkel GJE, Greving JP, et al.

Neurology 2017; 88:1600-1606.



To develop a risk score that estimates 3-year and 5-year absolute risks for aneurysm growth.


From 10 cohorts of patients with unruptured intracranial aneurysms and follow-up imaging, we pooled individual data on sex, population, age, hypertension, history of subarachnoid hemorrhage, and aneurysm location, size, aspect ratio, and shape but not on smoking during follow-up and family history of intracranial aneurysms in 1,507 patients with 1,909 unruptured intracranial aneurysms and used aneurysm growth as outcome. With aneurysm-based multivariable Cox regression analysis, we determined predictors for aneurysm growth, which were presented as a risk score to calculate 3-year and 5-year risks for aneurysm growth by risk factor status.


Aneurysm growth occurred in 257 patients (17%) and 267 aneurysms (14%) during 5,782 patient-years of follow-up. Predictors for aneurysm growth were earlier subarachnoid hemorrhage, location of the aneurysm, age >60 years, population, size of the aneurysm, and shape of the aneurysm (ELAPSS). The 3-year growth risk ranged from <5% to >42% and the 5-year growth risk from <9% to >60%, depending on the risk factor status.


The ELAPSS score consists of 6 easily retrievable predictors and can help physicians in decision making on the need for and timing of follow-up imaging in patients with unruptured intracranial aneurysms.


This abstract is cited in the Neurochecklist:

Cerebral aneurysms: risk factors for rupture

Abstract link

Aneurysm with a surgical clip across the the neck or base. UMHealth System on Flikr.
Neurochecklists updates

40 very handy and practical neurochecklists

Neurochecklists now contains >2000 checklists on all aspects of neurology.
Many checklists come to the rescue only to fill a knowledge gap.
By Samurai Gandhi - Own work, CC BY-SA 4.0, Link
By Samurai GandhiOwn work, CC BY-SA 4.0, Link
Most neurochecklists however address important practical questions or outline pragmatic steps in managing neurological disorders.
House of Knowledge. Ian Parkes on Flikr.
House of Knowledge. Ian Parkes on Flikr.
To illustrate, below is a selection of 40 handy neurochecklists


Anticoagulants: bridging therapy for surgery
Antiepileptic drugs (AEDs): choice with medical conditions
Apomorphine test
Cluster headache (CH): chronic prophylaxis
Cerebral vein thrombosis (CVT): investigations


Dementia: safety and driving risks
Diaphragmatic paralysis: neurological causes
Drug induced Parkinsonism: risk factors and causes
Epilepsy: patient information
Essential tremor (ET): drug treatment


Falls: management
Genetic counselling
HyperCKaemia: neurological causes
Lumbar puncture (LP): indications and precautions
Lyme Neuroborreliosis: management


Migraine prophylaxis: drugs
Mitochondrial diseases: investigations
Motor neurone disease (MND): supportive care
Multiple sclerosis (MS): general investigations
Pregnancy and myasthenia gravis (MG): management


Myelopathy with normal MRI
Myotonic dystrophy type 1: assessments and monitoring
Neurological complications of liver transplantation
Neurosarcoidosis: treatment
Neurosyphilis: clinical features


Peripheral neuropathy (PN): red flags for ominous causes
Pineal cysts: monitoring
Psychogenic seizures: management
Subarachnoid haemorrhage (SAH): complications
Sudden unexpected death in epilepsy (SUDEP): management


Syncope: red flags for admission
Thrombolysis: bleeding risk prediction tools
Trigeminal neuralgia (TN): management
Tic disorders: differential diagnosis and management
Passive tilt table test: indications and contraindications


Transient loss of consciousness (TLOC): assessment
Vitamin B12 deficiency: tests of B12 metabolites 
Warfarin: switching to new oral anticoagulants
Wernicke’s encephalopathy: risks and clinical features
Young onset dementia


Explore these and many other practical checklists on Neurochecklists

By Ansonlobo - Own work, CC BY-SA 4.0, Link
By AnsonloboOwn work, CC BY-SA 4.0, Link