1. Chiari malformation and syrinx
Case presentation and short lecture
This is the condensed version, suited to a general Principles audience where the participants are not primarily neurosurgeons.
Presenter’s name Arial 24 pt
Meeting Arial 24 pt
Presenter’s title Arial 20 pt
City, Month, Year Arial 20 pt

2. History 35-year-old woman Shoulder and arm pain
Investigated for work-related repetitive stress injury
Some shoulder pathology on scan
Query cervical radiculopathy component
Routine MRI cervical spine
Present this history to illustrate how less expected pathology can be found.

3. MRI Imaging findings? This is the MRI scan of the described patient.
Participants to describe:
MRI T2 weighted sagittal image of cervical spine
Chiari type I malformation (tonsillar herniation below the foramen magnum)
Syringomyelia (syrinx) extending from C5 to T1 vertebral body level
Spondylotic changes with C5/6 and C6/7 disc bulges
Imaging findings?

4. What are the possible findings on physical examination?
Participants to mention:
Lower motor neuron weakness and signs in the upper limbs at the level of the syrinx
Upper motor neuron signs at or below the level of the syrinx (hyperreflexia, Hoffmann’s positive, upgoing plantars)

5. History and MRI 35-year-old woman Shoulder bursitis
Hands and gait normal
Hyperreflexic
Hoffmann’s positive
“Ice-cream” headaches every time she coughs since childhood
Present these as the actual symptoms and signs for the patient with the illustrated MRI scan.
Emphasize the cough headache. Exertional occipital headache is a hallmark of Chiari I malformation.

6. Chiari malformations: hindbrain herniation syndromes
Cleland described a case in 1883
Chiari published his series in 1891
Born in Vienna (1851–1916)
Professor of Pathology in Prague, then Strasbourg
“Concerning alterations in the cerebellum resulting from cerebral hydrocephalus”
Deutsche Medizinische Wochenscrift; 1891
Arnold described a case in 1894
The basic history on Chiari malformations is mainly based on the pathology works of Chiari.
The name Arnold-Chiari comes from cases described by Arnold or his students at some later date that fit the descriptions of Chiari.

7. Chiari malformations Type Features I
Cerebellar tonsils below foramen magnum II
Further hindbrain structures (vermis, 4th ventricle, medulla, pons) below foramen magnum
Often with myelomeningocele
III
Hindbrain herniation into a high cervical meningocele
Three main types, with type IV being cerebellar hypoplasia which falls outside the descriptive context of the rest of the types.
Increasing severity of herniation, with type I being the most common to present in later life.

8. Chiari malformations Type I Usually adult onset
May have and can present with hydrocephalus
May have and can present with syringomyelia
May have scoliosis
Occipital exertional headache
Associated symptoms, signs and conditions of Chiari type I.

9. Type I Chiari malformations—investigations
Plain x-ray
May see skull and cervical spine abnormalities
Possibly scoliosis
MRI
Caudal displacement of cerebellar tonsils below foramen magnum (more than 5 mm)
Assess for any mass lesions in brain
Assess whole cord for syrinx/abnormalities
Descriptors of findings on relevant imaging.

10. MRI
MRI on the left shows the Chiari malformation with a syrinx. The axial scan on the right demonstrates no intracranial abnormalities.
Learning point: It is important to exclude intracranial mass lesions as a contributor to a Chiari herniation condition.

11. Type I Chiari malformation with syringomyelia

12. Comparison of normal and type I Chiari malformation
Normal tonsillar level
Low tonsillar level
Comparison of MRI scans of a normal patient and one with Chiari malformation.

13. Type I Chiari malformation and cerebrospinal fluid pathways
Reminder of the cerebrospinal fluid (CSF) pathways.
Learning point: Chiari herniation causes occlusion to the craniovertebral flow of CSF and hence a build-up of intracranial pressure on exertion and symptoms.

14. Type I Chiari malformation
Opisthion-basion line
(Level of foramen magnum)

15. Type I Chiari malformation—management
Nonoperative
If not symptomatic and no other abnormalities
Mass lesions/hydrocephalus
Treat these first
Foramen magnum decompression
For the hindbrain herniation
Syringomyelia
Treating any hydrocephalus or the hindbrain herniation will usually resolve a syrinx
Otherwise, consider shunting the syrinx
Learning points:
Do not treat if asymptomatic.
Treat associated intracranial abnormalities first—they may be causing the Chiari herniation.
Otherwise treat the Chiari herniation with a foramen magnum decompression. This will often resolve the syrinx.
If the syrinx persists and is symptomatic, then directly shunt the syrinx.

16. Syringomyelia Communicating Noncommunicating
Primary dilation of central canal into cord
Usually associated with Chiari malformation
Noncommunicating
Cyst within cord substance
Not connected to central canal
Posttraumatic: tumor, etc
Syrinx (syringomyelia) is classified into communicating and noncommunicating. In Chiari malformation, it is the communicating type.

17. Syringomyelia—symptoms
Very variable
Sensory loss
Suspended “cape” dissociated sensory loss
Pain/temperature loss, touch/proprioception preserved
Painless burns
Occipital or spinal pain
Lower motor neurons, hand/arm weakness
Neurogenic arthropathies (Charcot joints)
Learning point:
Syringomyelia itself can present with very variable symptoms, but sensory disturbance and weakness can present subtly and progressively.

18. Describe the changes between these scans
Participants to describe:
MRI scan, T2 weighted sagittal image with the left being preoperative and the right being postoperative.
There has been foramen magnum decompression (the bone is removed and there is an element of posterior fossa sagging).
The cerebellar tonsils are no longer descended and impacted.
The syrinx has collapsed in size.
This illustrates how a foramen magnum decompression can also improve the syrinx itself.

19. MRI Preoperative After foramen magnum decompression
Comparison of MRI scans to show effects of foramen magnum decompression.
Preoperative
After foramen magnum decompression

20. Take-home messages
Chiari malformation is the descent of hindbrain structures.
Type I is most common in adults.
Exertional occipital headache is a classic symptom.
It is associated with syringomyelia and scoliosis.
Syringomyelia presents with variable features.
MRI is the best investigation.
Treatment sequence:
Cranial pathology
Foramen magnum decompression
Syrinx
Summary key learning points.

21. Excellence in Spine

22. Foramen magnum decompression
Decompress impacted foramen magnum
Suboccipital decompression
C1 laminectomy
Lower if more caudal descent
Dural opening
Often tight band corresponding to C1 periosteum
Dissection of adhesions
Tonsillar reduction
Duraplasty (patch graft)
These are the procedural steps in foramen magnum decompression.
Tonsillar reduction can be carried out with bipolar diathermy, taking care to look out for the brainstem blood vessels. This shrinks the tonsils upwards.
Learning point—decompressing the bone elements alone may not be sufficient and there is often a constricting dural band at the level of the herniation. Duraplasty is therefore required. The patch graft can be synthetic, but autologous fascia lata can be best tolerated and result in less sensitivity reactions.