What are the pain sensitive intracranial structures?

Brain itself is pain insensitive. 

The following intracranial structures are pain-sensitive:

1. Meningeal arteries
2. Proximal portions of the cerebral arteries
3. Dura at the base of the brain
4. Venous sinuses
5. Cranial nerves 5, 7, 9, and 10, and cervical nerves 1, 2, and 3

What are the mechanisms causing headaches?

• Distortion or traction of Dura, Venous Sinuses or Blood vessels: 

• Drainage of CSF in erect posture causes headache, secondary to traction on the venous sinuses when the brain sinks toward the tentorium as it loses CSF flotation
• Intracranial mass distorts the dura or the arteries at the base of the brain 
• Distortion due to raised ICP 

• Distension of a vessel

• Distension of extracranial and occasionally intracranial arteries is thought to be the cause of pain in migraine (activate the trigeminal nerve terminals in the vessel wall)

• Inflammation

• Inflammation in the subarachnoid space can result in headache. Inflammation can be caused by infection, hemorrhage, or chemical irritation
• Inflammation of vessel wall by autoimmune process. eg Giant cell arteritis

• Referral of Pain

• Lesions above the tentorium - referred pain in trigeminal nerve distribution (the forehead or behind the eye) - because the dura in this region is supplied by the trigeminal nerve
• Lesions in the posterior fossa - 
• referred pain in the ear and the back of the head - because this part of the dura is supplied by cranial nerves 9 and 10 and the upper three cervical roots
• refer pain to orbit -  termination of orbital (ophthalmic division) pain nerve fibers in the lowest part of the spinal nucleus of the trigeminal nerve, which also receive termination of the upper cervical pain afferent nerve fibers 
• referred pain to ear - Irritation of cranial nerves 7, 9, and 10 - because the ear has cutaneous supply from each of these nerves as well as cranial nerve 5.

What are the types of Headaches?

For the purpose of history taking, headaches can be divided into two types:

• Primary- no identifiable cause on examination or investigation and diagnosis is based on  recognizing a pattern, e.g.
• Migraine
• Cluster headache
• Tension-type headache
• Secondary - definite identifiable cause on examination or investigation, e.g. 
• Brain tumors
• Meningitis
• Sub-arachnoid hemorrhage 
• 90% - primary headaches, less than 10% are secondary headaches (Rasmussen 1991)

What are the headache "Red Flags"?

• Worst Headache ever
• New onset Headache
• Onset after age of 50 yrs
• Change in pattern of headache
• Worsening headache
• Sudden onset during exertion, sneezing, coughing
• Headache with postural variation
• Headache in setting of malignancy or HIV
• Headache associated with Neurological symptoms or signs
• Associated with systemic symptoms - fever, weight loss and chronic cough

What history to take in a patient presenting with Headache?

Duration

Exact duration as reported by patient

NEW onset headache or something that has been there since before and has worsened now

Onset ( sudden/ gradual )

Acute onset, severe, first and worst headache, the common possibilities are sub-arachnoid hemorrhage, vascular dissection, pituitary apoplexy

Gradual onset – migraine(mins to days), SDH, GCA(days to months)

Severity

verbal rating scale from 0 to 10

Character

Pulsatile or throbbing or hammering (Raised ICP Headaches/ Migraine)

Dull featureless pain (Tension type headache)

Boring sharp- cluster HA

Time of occurrence

Raised ICP headaches - More in morning, May waken the patient at an early hour

Frequency

Increase in frequency - red flag

Distribution

Frontal or Holocranial - Raised ICP

Band like - tension headaache

Aggravating factors

Exertion, coughing, sneezing, stooping, and straining at stool

Changes in posture (increases in supine - ↑ICP , increases in upright – low CSF pressure headache)

Relieving factors

Improvement on lying flat - low pressure headache

Associated features

Blurring of Vision - Papilloedema

Diplopia, the commonest cause of which is abducens nerve paresis

Nausea & vomiting – migraine, ↑ICP

Neck stiffness – meningeal process

Changes in consciousness

Focal neurological symptoms

References

• Ravishankar K. The art of history-taking in a headache patient. Ann Indian Acad Neurol. 2012;15(Suppl 1):S7–S14. doi:10.4103/0972-2327.99989
• Rasmussen BK, Jensen R, Schroll M, Olesen J. Epidemiology of headache in a general population – a prevalence study. J Clin Epidemiol. 1991;44:1147–57
• https://www.dartmouth.edu/~dons/part_2/chapter_18.html

12/24/2019 10:06:00 PM

What are Arnold Chiari Malformations?

• These comprise a group of abnormalities involving the rhombencephalon (hindbrain) and the contents of the CV junction 
• With common feature of impaired CSF circulation through the foramen magnum  
• May be Congenital or Acquired
• Ranging from simple herniation of the cerebellar tonsils through the foramen magnum to complete agenesis of the cerebellum 
• Presently there is no consensus regarding the precise definition, classification, etiology and the surgical management 
• Five types 
• No anatomical or embryological correlation between them 

Historical Background of Arnold Chiari Malformations

• 1883, John Cleland (Professor of anatomy in Glasgow, Scotland) - described hindbrain hernia in a child with myelodysplasia.
• 1891 and 1896, Hans Chiari- (Professor of Pathology at German University, Prague, Czechoslovakia): analyzed data from >40 postmortem examinations of patients with hindbrain malformations
• Chiari malformations I, II and III were coined in the earlier work and Chiari malformation IV was added in 1896 publication. 
• 1894, Julius A. Arnold(Professor of Pathology at Heidelberg, Germany)- described a single myelodysplastic patient with associated hindbrain herniation.
• Schwalbe & Gerdig included Arnold name in the eponym & designated it ARNOLD –CHIARI malformation 

What are the types of Chiari Malformations?

Chiari type 0 malformation

• alteration in Cerebro Spinal Fluid (CSF) hydrodynamics at the level of the foramen magnum. 
• they have syringomyelia either without tonsil herniation or with only mild tonsil herniation

Chiari Type I malformation

• caudal herniation of the cerebellar tonsils more than 5 mm below the foramen magnum
• typically associated with hydrosyringomyelia.
• not usually accompanied by descent of the brain stem or IV ventricle, nor associated with the presence of hydrocephalus.
• Most common type
• Presents in young 

Chiari type II malformation

• caudal herniation of the cerebellar vermis, brain stem, and IV ventricle through the foramen magnum. 
• associated with myelomeningocele, hydrocephalus, and, less frequently, hydrosyringomyelia. 
• hypoplastic tentorium cerebelli, cranial lacunae, anomalies of the Sylvius aqueduct may exist.

Chiari type III malformation

• consists of occipital encephalocoele, with some of the intracranial defects associated with Chiari II malformation.

Chiari type IV malformation

• cerebellar aplasia or hypoplasia, associated with aplasia of the tentorium cerebelli.

Images showing various Chiari malformations

Image of a Type 1 Arnold-Chiari Malformation. The cerebellum has descended 7mm and there are herniated cerebellar tonsils into the foramen magnum.

Artist's representation of a Chiari II malformation showing the points of potential obstruction that yield different subtypes of hydrocephalus

Neonate with Chiari malformation type III.T2-weighted mid-sagittal MRI scan of the patient shows a small posterior fossa, an deep parieooccipitalis fissure (open arrow), ad a partial callosal agenesis (curved arrow), and a caudal herniation of part of the brain stem through the foramen magnum, with inferior tip appearing between C5 and C6 (closed arrow). (https://www.sciencedirect.com/science/article/pii/S1930043315302697)

T1 weighted sagittal MRI showing a so called “Chiari IV” or primary cerebellar agenesis. There is a tiny portion of residual quadrangular lobule just caudal to the tectum and a normal sized posterior fossa. No associated meningomyelocele is present.

References

• Greenberg Handbook of Neurosurgery
• Fernández AA, Guerrero AI, Martínez MI, et al. Malformations of the craniocervical junction (Chiari type I and syringomyelia: classification, diagnosis and treatment). BMC Musculoskelet Disord. 2009;10 Suppl 1(Suppl 1):S1. Published 2009 Dec 17. doi:10.1186/1471-2474-10-S1-S1 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2796052/
• Hidalgo JA, Varacallo M. Arnold Chiari Malformation. [Updated 2019 Nov 6]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2019 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK431076/
• https://commons.wikimedia.org/wiki/File:MRI_of_human_brain_with_type-1_Arnold-Chiari_malformation_and_herniated_cerebellum_es.jpg
• https://commons.wikimedia.org/wiki/File:Chiari2.jpg
• Chiari malformation type III: Case report and review of the literature. Christina Andica, Ristaniah D. Soetikno. Radiology Case Reports, 8, 3, 2013 https://doi.org/10.2484/rcr.v8i3.831
• The Chiari malformations. Donald M. Hadley. Neurology in Practice, 72, 2, 2002 http://dx.doi.org/10.1136/jnnp.72.suppl_2.ii38

Related Posts

CLASSIFICATION OF ARNOLD CHIARI MALFORMATIONS

https://www.worldsurgeryforum.net/2019/12/classification-of-arnold-chiari.html

ARNOLD CHIARI MALFORMATION RADIOLOGY AND BASIC CONCEPTS

https://www.worldsurgeryforum.net/2020/05/arnold-chiari-malformation-radiology.html

SPINAL DYSRAPHISM : QUICK TOPIC REVIEW AND MCQ POINTS

https://www.worldsurgeryforum.net/2019/10/spinal-dysraphism-quick-topic-review.html

12/02/2019 10:34:00 PM

Spina Bifida Occulta

1. Of the three embryonic layers (ectoderm, mesoderm, and endoderm), the neural structures develop from the ectoderm. (MCQ)

2. The neural tube forms from the neural placode at approximately 21 days of gestation (MCQ)

3. It is important to realize that neural tube defects have already formed by the time pregnancy is diagnosed; thus, prevention of these defects by the administration of folic acid has to commence prior to 21 days of gestation. (MCQ)

4. The disorders of spine, vertebral column and nerve roots are included in spinal dysraphisms. They can be classified as spina bifida aperta (open defects, usually apparent) and spina bifida occulta (closed defects, commonly missed by an untrained observer)

Myelomeningocele

5. Myelomeningocele is the most common type of spina bifida aperta (MCQ)

6. Thoracic defects have the highest incidence of weakness and sacral defects often have only bladder involvement. (MCQ)

7. Hydrocephalus is present in 80% of patients. (MCQ)

8. Thoracic defects have the highest incidence and low sacral defects the lowest incidence of hydrocephalus. (MCQ)

9. Spina bifida is associated with Chiari II malformation. It occurs in 90% to 95% of cases. (MCQ)

10. Associated brain anomalies include corpus callosal anomalies, fused tectal plates, and thalamic fusion.

11. Surgical closure of the myelomeningocele is undertaken within 24 to 48 hours of birth to avoid CNS infection (MCQ)

12. Of children with myelomeningocele, 60% to 70% will ultimately require a shunt insertion (MCQ)

13. Only 15% to 30% of children will require a Chiari decompression (MCQ)

14. Children with Myelomenigocele have a 20% to 65% incidence of latex allergies. Thus universal latex allergy precautions are adopted for this group of children (MCQ)

15. There is no specific treatment for occult spina bifida if the abnormality is limited to the bone. Usually these deformities are found at the last lumbar vertebrae (L5) or at the first sacral vertebrae (S1)

16. - The term spina bifida occulta includes following:

a. Simple Spina Bifida Occulta: Mildest form of spina bifida. Usually asymptomatic.

b. Dermal Sinus: Dermal sinus tract from the cutaneous to spinal subarachnoid space. It can cause ascending infection

c. Diastematomyelia: Spinal cord is split into two hemicords, often by a bony or fibrous band that tethers the cord. Needs to be repaired surgically

d. Lipomyelomeningocele: There is fatty tissue in the spinal cord and in the spinal canal tethering the cord. Associated neurologic deficits, although uncommon at birth, usually develop later because of the tethering

Related Posts

CLASSIFICATION OF ARNOLD CHIARI MALFORMATIONS

https://www.worldsurgeryforum.net/2019/12/classification-of-arnold-chiari.html

ARNOLD CHIARI MALFORMATION RADIOLOGY AND BASIC CONCEPTS

https://www.worldsurgeryforum.net/2020/05/arnold-chiari-malformation-radiology.html

SPINAL DYSRAPHISM : QUICK TOPIC REVIEW AND MCQ POINTS

https://www.worldsurgeryforum.net/2019/10/spinal-dysraphism-quick-topic-review.html

10/08/2019 10:46:00 PM

Choices:

1. Streptococcus agalactiae 
2. Hemophilus influenza 
3. Staphylococcus epidermiditis 
4. Neisseria meningitidis

Explanations:

• The most common organisms for neonatal meningitis is streptococcus agalactiae 
• Hemophilus influenza was the most common organism before the introduction of vaccination 
• Neisseria meningitidis is most common in adults 
• Staphylococcus epidermidis is responsible for 75 percent of shunt related meningitis

8/04/2019 10:12:00 PM

Choices:

1. Subventricular zone 

2. Substantia nigra 

3. Subgranular zone 

4. 1 and 3

Explanation:

Neurogenesis in adults occurs in the subventricular zone lining the ventricles and at the subgranular zone at the dentate gyrus of the hippocampus. 

Neurons and glial cells are produced by multipotent stem cells

Contrary to the long-held belief that neurogenesis tapers off with the end of early postnatal development, the mammalian brain retains the capacity to generate new neurons throughout life. 

Adult neural stem/progenitor cells (NSPCs) are responsible for the generation of new neurons and reside in two main locations in the adult brain: 

• the subventricular zone (SVZ) lining the lateral ventricles, and 
• the hippocampal dentate gyrus (DG) 

( Gage, 2000)  (Doetsch et al., 1999; Bonaguidi et al., 2011)

https://dev.biologists.org/content/141/10/1983

8/02/2019 07:22:00 AM