Case record...Congenital syringomyelia

1. CASE OF THE WEEK
PROFESSOR YASSER METWALLY
CLINICAL PICTURE
CLINICAL PICTURE
A 30 years old female patient presented clinical with gradual progressive atrophy of the small muscles of the both
hands, Bilateral C5,C6 segmental hypoalgesia.
RADIOLOGICAL FINDINGS
RADIOLOGICAL FINDINGS
Figure 1. A case of congenital syringomyelia, MRI T1 images showing a longitudinal multisegmental continuous
syringomyelic cavity involving the whole of the cervical spinal cord and extending to the upper dorsal segments with
complete absence of transverse band and septations (Type I syringomyelic cavity). Notice herniation of the cerebellar
tonsils below the level of the foramen magnum. The intracavitary MRI signal of the syringomyelic slit is identical with
that of the CSF signal in the subarachnoid spaces in MRI T1 and T2 images.

2. Figure 2. A case of congenital syringomyelia, MRI T1, T2 images showing a longitudinal multisegmental continuous
syringomyelic cavity involving the whole of the cervical spinal cord and extending to the upper dorsal segments with
complete absence of transverse band and septations.(Type I syringomyelic cavity). Notice herniation of the cerebellar
tonsils below the level of the foramen magnum. The intracavitary MRI signal of the syringomyelic slit is identical with
that of the CSF signal in the subarachnoid spaces in MRI T1 and T2 images.
Figure 3. A case of congenital syringomyelia, MRI T1,T2 images showing a longitudinal multisegmental continuous
syringomyelic cavity involving the whole of the cervical spinal cord and extending to the upper dorsal segments with
complete absence of transverse band and septations (Type I syringomyelic cavity). Notice herniation of the cerebellar
tonsils below the level of the foramen magnum causing marked stenosis at that level. The intracavitary MRI signal of
the syringomyelic slit is identical with that of the CSF signal in the subarachnoid spaces in MRI T1 and T2 images.

3. Figure 4. MRI T1,T2 images showing a central syringomyelic cavity representing dilatation of the central canal of the
spinal cord, notice the peripheral signal void area (A) that probably represent a CSF flow void sign inside the
syringomyelic cavity. The intracavitary MRI signal of the syringomyelic slit is identical with that of the CSF signal in
the subarachnoid spaces in MRI T1 and T2 images.
The case represents a congenital subtype syringomyelia because of the following: [19]
 The presence of Arnold Chiari malformation which represents the aetiopathogenic factor of congenital
syringomyelia
 The central location of the syringomyelic cavity which represents dilation of the central canal of the spinal cord.
 The syringomyelic cavity is a continuous slit without transverse bands or septations.
 The involvement of the cervico-dorsal region of the spinal cord which is commonly the site of involvement in
congenital syringomyelia.
 The intracavitary MRI signal of the syringomyelic slit is identical with that of the CSF signal in the
subarachnoid spaces in MRI T1 and T2 images.
Table 1 Differences between congenital and neoplastic syringomyelia [19]
Congenital syringomyelia Neoplastic syringomyelia
The presence of Arnold Chiari malformation which
represents the aetiopathogenic factor of congenital Absence of Arnold Chiari malformation
syringomyelia
Two types of cavities are noted.
1- A peripheral irregular cavities inside the tumors which
The syringomyelic cavity is centrally located and represents cystic breakdown of tumor tissue (the
represents dilation of the central canal of the spinal cord cavitations are part of the tumor).
(hydromyelia).
2- Cavitations rostral and caudal to the spinal tumors,
these cavitations are not part of the tumors and represents
intramedullary cavitations due to CSF flow obstruction.
It commonly involves the cervico-dorsal region Any part of the spinal cord can be involved.
The syringomyelic cavity is a continuous slit without
Transverse bands and septations are common.
transverse bands or septations.
The intracavitary MRI signal of the syringomyelic slit is The intracavitary MRI signal of the syringomyelic slit is
identical with that of the CSF signal in the subarachnoid different from that of the CSF signal in the subarachnoid
spaces in MRI T1 and T2 images. spaces in MRI T1 and T2 images.

4. DIAGNOSIS:
DIAGNOSIS: CONGENITAL SYRINGOMYELIA WITH TYPE I ARNOLD CHIARI MALFORMATION
DISCUSSION
DISCUSSION
Syringomyelia is a chronic disorder involving the spinal cord or the medulla or both. Pathologically it is characterized
by the development of cavitations and gliosis within these structures. When cavitations and gliosis extend to the
medulla (bulb), the term syringobulbia is applicable.
The present term quot;syringomyeliaquot; was devised by ollivier in 1837 from the two Greek words quot;to become hollowquot; and
quot;marrowquot;. This term was intended to describe any cavitation in the spinal cord including even the central canal which
had not been recognized as a normally occurring structure until stifling described it in 1859. [19]
In order to understand the pathogenesis of congenital syringomyelia it is necessary to understand the dynamics of the
CSF flow in the central canal of the spinal cord and the surrounding subarachnoid spaces.
The bulk flow of the CSF follows a downward route behind the spinal cord and posterior to the dentate ligament from
the cervical region and down to the lumber region and then upward in front of the spinal cord to the basilar cisterns.
Pressure waves are generated by the distension and the collapse of the cerebrovascular and the spinovascular beds and
are felt to be responsible for the CSF pulsation. As in case of the blood, the propagation of the pulse waves is
independent of and much faster than the blood velocity. Also the propagation of the CSF pulse wave is much more
rapid than the actual CSF movement.
The CSF down flow, which occur behind the spinal cord, begins during systole and ceases during diastole and is of 10
times greater volumetric magnitude than the ventricular pulse.
The ventricular CSF pulse wave is generated by the pulsation of the choroid plexus in the lateral ventricles which then
escapes through the foramen of magendi into the subarachnoid spaces and is progressively damped as it passes down
behind the spinal cord through the foramen magnum; in this way the central canal of the spinal cord is bypassed and is
not subjected to the ventricular fluid pulse wave and is left behind as a potentially distensible vestigial structure.
Around 30% of the CSF is formed in the central canal of the spinal cord and flow upward by the milking action of the
CSF pressure waves that are transmitted to the walls of the spinal cord. These pressure waves are thought to be caused
by engorgement of the spinal venous plexus and are most marked during coughing, straining and other valsalvas effect
producing maneuver. [19]
THE CRANIOCERVICAL ANOMALIES [19]
The following craniocervical anomalies are found in congenital syringomyelia:
Arnold-Chiari malformation (100%) Cerebellar tonsillar ectopia
Basilar invagination (25%) Complete intracranial invagination of the atlas and axis
Syringobulbia (15%) Medullary cavitation
Hydrocephalus (10%) mmm
Klippel feil anomaly (5%) Complete fusion of bodies and arches of adjacent vertebrae
Assimilation of the atlas (5%) Atlanto-occipital fusion
 Arnold-Chiari malformation
Stenosis of the foramen magnum, due to cerebellar tonsillar ectopia, with the resultant of reduction of the volume of the
foramen of magendi, as it opens anatomically between the two cerebellar tonsils, will disrupt the normal CSF
circulations and pulse waves. This will interfere with the escape of the ventricular pulse waves and pressure waves
generated by the choroid plexus situated at the obex of the 4th ventricle (this escape normally occurs through the
foramen of magendi and the foramen magnum) and direct them into the central canal of the spinal cord, resulting in
syrinx formation.

5. Figure 5. Chiari I malformation
Figure 6. The anatomic substrate of congenital
syringomyelia and/or hydromyelia is based upon
cerebellar tonsillar ectopia in fetal life. Blockade of the
foramen of magendi and stenosis of the foramen
magnum will funnel the CSF arterial pulse waves into
the spinal canal, distending it and eventually creating
hydrosyringomyelia .
Stenosis of the foramen magnum and the foramen of magendi can also inhibit the CSF upflow from the central canal of
the spinal cord towards its intracranial sites of resorption and causes increased spinal CSF pressure. The CSF, driven
by the high intraspinal pressure, will thin filter into the spinal cord resulting in longstanding cord oedema that
eventually causes cavitations within the spinal cord parenchyma.
Figure 7. A, CT myelography, B, MRI T1 image showing Arnold Chiari malformation (A,B), basilar invagination (A)
and syringobulbic slit (B)

6. Figure 8. MRI T1 images (A,B) showing Arnorld-Chiari malformation.
Interestingly the foramen of magendi (which is situated at the caudal end of the 4th ventricle and can easily be
appreciated on the T1 MRI sagittal images) is appreciated as being markedly diminished in volume and occasionally
totally obliterated and unidentifiable in all patients with tonsillar ectopia. In some patient the foramen of magendi is
transformed into a long slit that opened below the level of the foramen magnum.
Figure 9. MRI T1 image showing a case with Arnold-Chiari malformation, notice the
tonsillar ectopia,adhesions between the herniated tonsils and the medulla,resulting in
marked stenosis of the foramen magnum and the foramen of magendi
Adhesion between the herniated cerebellar tonsils and the posterior aspect of the cervico-medullary junction could be
appreciated in all cases, so besides stenosis of the foramen magnum and the foramen of magendi that is induced
mechanically by the crowding of the foramen magnum by the herniated cerebellar tonsils, these adhesions will further
compromise the volume of the foramen of magendi.

7. Figure 10. Normal MRI T1 image (left) and two cases with Arnold Chiari malformation (middle and right images),
notice the tonsillar ectopia,adhesions between the herniated tonsils and the medulla, resulting in marked stenosis of the
foramen magnum and the foramen of magendi, also notice the syringobulbic slit (right image)
Figure 11. Arnold Chiari malformation associated with hydrocephalus
and syringomyelia, notice evidence of surgical intervention
 Syringobulbia
Syringobulbic slits are demonstrated in 15% of cases with syringomyelia and they are composed of two types, the first
type extends asymmetrically into the lateral tegmentum of the medulla, in the presumed area of the descending root of
the trigeminal nerve. The other type extends along the median raphe. Direct communication between the bulbic slits
and the 4th ventricle is occasionally demonstrated in some cases. [19]

8. Figure 12. MRI T1 images showing a lateral syringobulbic slit with definite communication with the 4TH ventricle and
the cervical syringomyelic cavity.
Figure 13. CT myelography showing a median syringobulbic slit,
notice the basilar invagination.
Direct communication between the bulbic slits and the cervical syringomyelic cavities is commonly demonstrated in
almost all cases, this is because syringobulbia is formed by fluid in the cervical syringomyelic cavities breaking upward
through the pyramidal decussation region to form a cavity in the bulb. Pulsatile fluid shifts in the cervical syringes are
responsible for the upward extension of these syringes. all the bulbic slits are demonstrated on both the T1 and T2
weighted MRI images, both in the axial as well as the sagittal planes.
Figure 14. A postmortem specimen showing Arnold- Chiari malformation and hydrocephalus
Hydrocephalus is demonstrated in about 10% of cases with congenital syringomyelia and is occasionally associated
with an abnormally elongated cerebellum and a markedly distorted 4th ventricle with significant reduction of its

9. volume. This probably indicates the existence of a graver degree of stenosis at the 4th ventricular level. This marked
degree of stenosis apparently results in hydrocephalus in addition to hydrosyringomyelia. Occasionally hydrocephalus
is associated with abnormally large cisterna magna .
Figure 15. A, This figure illustrates the position of the downwardly displaced portions of cerebellum. The lower
medulla has a congenital quot;kink.quot; The position of the foramen magnum, as it appeared in life, is marked on the image.
B, This figure illustrates the brain stem and cerebellum cut sagitally in a case of Arnold-Chiari malformation. The
arrow points to the cerebellar tonsils or quot;pegsquot; of cerebellum which have been displaced caudally over the roof of the
medulla.
 Basilar invagination
Complete intracranial invagination of the atlas and axis (basilar impression or invagination) is demonstrated in about
25% of cases with congenital syringomyelia. Basilar impression acts by reducing the volume capacity of the posterior
fossa and crowds the cerebellum thus producing cerebellar tonsillar herniation, thereby sitting up the substrate for the
funneling of the CSF pressure waves into the central canal of the spinal cord thus creating hydrosyringomyelia. In all
cases with basilar impression the odontoid process was fixed with no evidence of subluxation.
Figure 16. Basilar invagination plain x ray (left) plain CT scan (middle) and MRI T1 image(right), notice that the
hyperintense odontoid (due to increased fat content) can be seen in touch with the pons
 Assimilation of atlas (atlanto-occipital fusion)
Assimilation of the atlas (complete fusion between the atlas and the occipital condyles) occur in about 5% of cases of
congenital syringomyelia. In atlanto-occipital fusion, the odontoid process is abnormally high, subluxated and
compressing the cervico-medullary junction posteriorly. The most significant finding in assimilation of the atlas with
neurological symptoms is an odontoid process with abnormal size, in abnormal position and with abnormal mobility .

10. Figure 17. High subluxated odontoid compressing the cervico-medullary zone in a case of assimilation of atlas
Figure 18. High subluxated odontoid compressing the cervico-medullary zone in a case of assimilation of atlas (left
plain x ray and right two images CT myelography)
When the atlas is fused with the occiput, flexion of the head results in partial forward subluxation of the fused atlas on
the axis. Posterior displacement of the odontoid process then occurs, resulting in compression of the cervico-medullary
junction. As the posterior luxation of the odontoid process is intermittent (only during head flexion), so intermittent
compression of the cervico-medullary junction might result, initially, in intermittent neurological manifestations.
Figure 19. High subluxated odontoid compressing the cervico-
medullary zone in a case of assimilation of atlas (left, plain x
ray,and right MRI T1 image)
THE SYRINGOMYELIC CAVITIES
Regarding the cervico-dorsal syringomyelic cavities, two types are demonstrated. The first one was composed of a
single, continuous slit-like or tubular cavity that extended through the whole cervico-dorsal region. The walls of these
cavitations are thin and smooth. Signal loss on the T2 weighted images (CSF flow void sign) is occasionally
demonstrated inside these cavitations. Patients harboring this type of cavitations are younger.

11.
Figure 20. MRI T1 image showing TYPE I syringomyelic cavit
Figure 21. MRI T1 images showing TYPE I syringomyelic cavity composed of a single, continuous slit-like or tubular
cavity that extended through the whole cervico-dorsal region. The walls of these cavitations are thin and smooth.

12. Figure 22. MRI T2 image (A) and CT myelography (B) showing TYPE I syringomyelic cavity composed of a single,
continuous slit-like or tubular cavity that extended through the whole cervico-dorsal region. The walls of these
cavitations are thin and smooth. Signal loss on the T2 weighted image (CSF flow void sign) is evident on the T2 image
On the other hand, the second type is characterized by thick walls and extensive intra-cavitary septations, transverse
bands and CSF multiloculations. The CSF flow void sign is not demonstrated inside these cavitations on the T 2
weighted images. Patients harboring this type of cavitations are older. [19]
Figure 23. MRI T1 images showing type II syringomyelic cavity characterized by thick walls and extensive intra-
cavitary septations, transverse bands and CSF multiloculations.

13. Figure 24. MRI T1 images (A) and MRI T2 image (B) showing type II syringomyelic cavity characterized by thick walls
and extensive intra-cavitary septations, transverse bands and CSF multiloculations. The CSF flow void sign can not be
demonstrated inside these cavitations on the T 2 weighted image.
From the pathological point of view syringomyelia is a chronic spinal cord disorder characterized by progressive
cavitations and gliosis. Cavitations occur early and progress up and down by the pulsatile fluid shifts inside the
syringomyelic cavities. Pulsatile fluid shifts inside the cavitations are caused by CSF pulsation in the subarachnoid
spaces that is transmitted to the fluids inside the syringomyelic cavities through the walls of the spinal cord. These
pulsatile fluid shifts are increased by coughing and straining and result in recurrent sucking and sloshing of the CSF
inside the syringomyelic cavities.
Figure 25. Type II syringomyelic cavities, notice the thick walls, and traverses septations
Such sucking and sloshing movements of the CSF inside the cavitations result, on short term basis, in progressive
extension of the cavitations up and down within the substance of the spinal cord. The pulsatile fluid shifts in the syrinx
cavities are thought to be responsible for the loss of signal on the T2 weighted images that has been termed CSF flow
void sign (CFVS). However on long term basis pulsatile fluid shifts in the syringomyelic cavities induce reactive gliosis
that ultimately results in the formation glial bands, septations and CSF multiloculations inside the syringomyelic
cavities. It also results in progressive thickening of the walls of the cavities and probably also reduction of the volume of
the cavitations.

14. Figure 26. Type I syringomyelic cavities.
These glial bands and septations will interfere with the CSF flow inside the cavitations by damping the pulsatile CSF
movement. This ultimately results in stasis of the CSF inside the cavitations and loss of the CSF flow void sign that was
initially present at a younger age.
Symptoms of syringomyelia are initially caused by the progressive cephalo-caudal extension of cavitations caused by
the pulsatile fluids shifts inside these cavitations. The pulsatile fluid shifts vary in intensity from time to time and from
one position to another. Engorgement of the epidural venous plexus by prolonged recumbency and during coughing
and straining also increases the intensity of the pulsatile fluid shifts. The variability of the intensity of the pulsatile fluid
shifts is reflected clinically as marked fluctuation of the intensity of the clinical symptomatology of some of these
patients to the point that some of them were initially misdiagnosed as MS.
At an older age group symptomatology of syringomyelia is caused mainly by the reactive gliosis that can interfere with
the blood supply of the affected segments and with the physiological function of the myelin sheath and neurons at the
affected zones, thus resulting in progressive deterioration of the clinical neurological deficits.
In congenital syringomyelia, shunting of the syringomyelic cavitations is probably indicated only when the CSF flow
void sign could be appreciated inside these cavitations on the T2 weighted images, especially when MRI also
demonstrates absence of any significant glial septations and/or CSF multiloculations, i.e. shunting is indicated only for
type I syringomyelic cavitations.
Early surgical treatment can relieve the distending force (i.e. sucking and sloshing CSF movements) and perhaps - on
long term basis - can prevent the gliotic zone which later surround the syringomyelic cavities. Post-operatic absence of
the CSF flow void sign that was initially present pre-operatively is an indication of a successful shunting.
SUMMARY
Tubular cavitation of the spinal cord, producing progressive neurologic symptoms, has long attracted interest. The
accumulation of cerebrospinal fluid (CSF) can lead to simple distension of the central canal of the spinal cord lined by
ependymal cells (ie, hydromyelia) or it can dissect into the surrounding white matter to form a paracentral cavity, in
which case none of the cavity is lined by ependyma (ie, syringomyelia). In many if not most cases, both hydro- and

15. syringomyelia are present, leading to the term quot;syringohydromyelia.quot; As the syringomyelic cavity expands, the initial
hydromyelic cavity compresses, and the communication between the two may atrophy and be lost. The distinction
between hydro- and syringomyelia may be difficult even after detailed histologic examination.
Syringomyelia could be congenital, and in such a case Arnold Chiari malformation should be present, or it might be
secondary to intramedullary or extramedullary spinal neoplasms, spinal trauma, spinal inflammatory conditions or
spondylitic myelopathy.
 Addendum
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