Lipomyelomeningocele

Management of
Lipomyelomeningocele

INTRODUCTION
• Congenital lumbosacral lipomas are the
most common form of occult spinal
dysraphism.
• They are part of a loco-regional
malformation involving almost always the
skin, the spine and the nervous tissue.
• The most characteristic neural anomaly is
a low-lying cord.

DEFINITION OF TYPES OF
SPINAL LIPOMA (5)
• Lipomyelomeningocele
• Lipoma of the conus medullaris (most common)
• A form of occult spinal dysraphism (OSD) in
which a subcutaneous fibrofatty mass traverses
the lumbodorsal fascia, causes a spinal laminar
defect, displaces the dura, and infiltrates and
tethers the spinal cord
• Fatty Filum
• Lipoma of the terminal filum
• The accumulation of fat within the terminal filum
and this lesion represents a less severe form of
OSD.
• The filum is usually thickened in and around the
regions of fat deposition.

SPINAL LIPOMA
• Intradural Spinal Lipoma
• Lipoma of the spinal cord. (Rare, 4%, Thoracic)
• Fatty accumulations that are completely intradural,
have no subcutaneous component, and manifest
symptoms when they become large enough to have
mass effect.
• These lipomas tend to be dorsally situated in the
spinal cord and may demonstrate an exophytic
component.
• Epidural Lipomatosis
• Excessive amounts of epidural fat are synthesized.
• The most frequent clinical setting for this is in a
patient receiving exogenous steroid agents, but it is
occasionally seen in cases of severe obesity.
• The excessive fat exerts mass effect on the
underlying neural structures and can cause a
compressive myelopathy or cauda equina syndrome.

SPINAL LIPOMA
• Spinal Angiolipoma
• Benign fatty harmartomas consisting of
abnormally differentiated vessels and adipose
tissue.
• They are commonly found in the skin, muscle,
bone, and oral cavity, but there are rare reports
of their appearance in the spine or with
extension to the brain.
• It is recognized that fat accumulations occur for
a variety of reasons include as a result of a
dysraphic event:
• lipomas of the conus medullaris
(lipomyelomeningocele)
• and lipomas of the terminal filum (fatty
filum).

LIPOMA OF THE CONUS
• The intradural lipoma is anchored to the
conus.
• The interface between the two structures
is usually resistant and whitish, extending
in average from L4 to S3.
• The intradural lipoma may compress the
cord.
• Strictly intradural lipomas are rare.

LIPOMA OF THE CONUS
Subtype (3):
• Dorsal Variant
• Lipoma that arises through a fascial defect and
attaches directly to the dorsal aspect of the
caudally descended conus medullaris;
• All nerve roots emerge from the ventral or
lateral surface of the neural tissue and lie in the
subarachnoid space.
• The lateral nerve roots are sensory, and the
more medial nerve roots are motor roots.
• Critical to the surgical approach is the junction
formed by the lipoma and the spinal cord
complex, as well as the position of the dural
attachment in relation to that complex.

LIPOMA OF THE CONUS
Subtype:
• Caudal Variant
• Lipoma that exits the area of the terminal filum
so that the cord becomes progressively larger
caudally.
• In this form of lipomyelomeningocele, the nerve
roots do transgress the lipoma.
• Many of these nerve roots are thought to be
non-functional and can be sacrificed after
stimulation.
• Although this caudal variation is difficult to
reform into a tubular structure, the cut end of
the lipoma may retract sufficiently cephalad to
lessen the likelihood that retethering will occur
postoperatively

LIPOMA OF THE CONUS
Subtype:
• Transitional Form
• Has elements of both dorsal and caudal
variants.
• Viable nerve roots pass through significant
amounts of lipoma before exiting.
• Typically these are asymmetrical and
associated with a rotational component of the
spinal cord.
• The process of distinguishing among these
three types of lipoma is usually straightforward;
however, in the literature scant regard is often
given to the differences.

Dorsal lipomyelomeningocele:
The lipoma is fixed to the dorsal surface of the conus
medullaris. The nerve roots emerge from the spinal cord
immediately anterior to the zone where the lipoma, dura,
and conus meet. The associated fatty accumulation
penetrates a bone and fascial defect and is in direct
continuity with a large subcutaneous fat accumulation.
Often the filum is thickened and infiltrated by fat.

Caudal lipomyelomeningocele:
Fat extends from within the central canal of the cord
through the caudal end where it intermixes with exiting
nerve roots. A transverse fibrous band is often present at
the level of the last intact lamina. Release of this band may
result in dural expansion

Transitional lipomyelomeningocele:
This lesion demonstrates components of both dorsal and
caudal variants of lipomyelomeningoceles.

Lipoma of the conus (lipomyelomeningocele)

Develops both subcutaneously and intradurally
The stalk joining these two components passes through a
defect of a spina bifida and of the dura

Dorsal Caudal
Transitional

Lipoma of the filum (fatty filum)

Involves the whole length of the filum or only part of it.
Dural sac is almost constantly normal
Roots around are always normal

Lipomas of the filum. Schematic representation of a typical
lipoma of the conus

MRI, T1
operative view sagittal view,
of a lipoma showing in
involving the another case a
whole lipoma of the fi
filum lum

LIPOMA OF THE CONUS
• Recognition, dissection and preservation
of the roots and of the interface may be
compromised by
• (1) the density of the adherences,
• (2) a posterolateral insertion of the
lipoma on the cord with then
intralipomatous roots
• (3) an extraspinal extension of the cord

Caudal insertion of the
lipoma on the cord.

lipoma inserted on the
posterolateral aspect of the cord

(T1 sequence), the terminal cord ends within
the lipoma and the interface is visible.

ASSOCIATED
MALFORMATIONS
• Most common: cutaneous and vertebral (90% of
cases)
• Cutaneous stigma on the midline of the back:
lumbosacral • Variable diagnostic values; e.g.
subcutaneous bump • very high in the case of bump, deviation of
very suggestive of a the intergluteal fold, or coexistence of two or
lipoma more lesions, whatever their type, low in the
case of atypical dimple, aplasia cutis,
dermal sinus, “queue de faune”
• very low in the case of hemangioma, port-
wine stain, hypertrichosis, fibroma
pendulum, pigmentary noevus, coccygeal
dimple
minor cutaneous anomaly (deviation of the
intergluteal fold)

Lumbar hemangioma (flat or raised, pink or red skin
lesion that consists of capillary vessels)

Hypertrichosis (localized patch or tuft of hair)

Atretic meningocele (skin lesion that looks
like a scar and is sometimes called a “cigarette burn”)

a Dermal sinus(small hole or opening in the
skin that appears as a dimple in the skin) with flat
hemangioma.
b Sacrococcygeal dimple.

ASSOCIATED
MALFORMATIONS
• The spina bifida involves often the whole sacrum,
extending frequently to L5-4.
• Sacral agenesis is rare, but almost constant in
patients with urogenital or anorectal anomalies.
• Scoliosis is generally related to vertebral bodies
malformations or shortening of a leg.
• Syringomyelia is noted in 25% of the patients
essentially at the lower cord.
• Brain anomalies are extremely rare (3%).
• Extra-axial malformations are described in almost .
of the cases, essentially urogenital and ano-rectal.

DECISION-MAKING:
DIAGNOSIS
• Prenatal diagnosis
• Ultrasonography
• from week 17 on the basis of a
lumbosacral spina bifida,
hyperechogenic skin, low-lying cord
and normal intracranial anatomy.
• lipoma revealing only at birth or at
the very end of the pregnancy

DECISION-MAKING:
DIAGNOSIS
• Perinatal diagnosis
• Cutaneous anomalies
• key of the diagnosis.
• Congenital deficits
• Rare
• Resulting from root malformations
• Exceptionally obvious, and bilateral
• Extremely difficult to assess in neonates
and infants
• Voiding difficulties
• frequently unapparent in the absence of
clear incontinence or repeated urinary
infections

DECISION-MAKING:
DIAGNOSIS
• Perinatal diagnosis
• Urodynamic studies at birth and every 6 months until
the age of two years, and at any age in case of
doubt, are recommended.
• MRI is the first necessary investigation in the
presence of a bump or of deficits to confirm the
diagnosis
• Sagittal and axial views in T1-T2 weighted
images are necessary.
• Fat saturation and gadolinium may be useful
• Ultrasonography must be proposed first under the
age of 2 months in asymptomatic babies with
cutaneous anomalies of low or very low diagnostic
value
• MRI can be avoided if ultrasonography is normal
• Brain MRI is unnecessary.

DECISION-MAKING:
DIAGNOSIS
• Diagnosis in children and adults
• Neurological symptoms are predominant
• Sphincter disorders,
• micturation difficulties, are the most
common.
• Incontinence results mainly from
dysuria, pollakiuria, urgent micturation
and incomplete voiding.
• Bladder infection or pyelonephritis is not
rare, due to urinary retention.
• Constipation necessitating digital
evacuation is not rare, but frequently
concealed by a pseudo diarrhea.

DECISION-MAKING:
DIAGNOSIS
• Neurological symptoms are predominant
• The neuro-orthopedic syndrome
• typically unilateral or asymmetrical
(clubfoot, equino-varus deformation,
clawing of the toes, hypotrophy of the
leg) and affects 1/3 of the patients
• Sexual dysfunction
• almost constant in symptomatic adults.
• The caudal syndrome (1.8–5.1%)
• associates sacral agenesis, presacral
mass and perineal malformation(s).
• Only in adulthood when symptoms are
limited to moderate bowel dysfunction
and unspecific neurological signs

DECISION-MAKING:
DIAGNOSIS
• Urodynamic studies
• should be part of the decision-
making work-up, even in the very
young and in case of unsuspected
urinary troubles.
• They may reveal a combination of
hyperactive bladder and vesico-
sphincter dyssynergia.
• Spinal MRI
• is necessary in all cases.

DECISION-MAKING:
EVOLVING DEFICITS
• The diagnosis of evolving deficits is often
difficult to make early due to their usually
slow progressiveness or even to assess.
• Urodynamic studies and/or
electromyography of the lower limbs are
therefore extremely useful at any doubt.

DECISION-MAKING:
FUNCTIONING SCORING SYSTEM

• This system takes into account the motor, sensory, vesical and anal handicaps.
• Normality is given a score of 5 for motor and urinary functions and of 4 for sensory
and anal functions.
• Asymptomatic patients have a score of 18.
• A normal life is compatible with a score above 15.

DECISION-MAKING:
SURGICAL INDICATIONS
presence of congenital deficits

presence of acquired or evolving deficits

early as possible
postoperative evolving deficits

mandatory

Surgery Redo Surgery

DECISION-MAKING:
Absence of deficits

Asymptomatic lipomas of the filum Asymptomatic lipomas of the conus

The treatment is not without risk (3.4% of
acceptable X neurological complications

Pattern of deterioration with or without surgery
being at least similar
Prophylactic Surgery
The pathology is far from being as severe
Does surgery have a truly as previously described
preventive effect?
Patients are better after surgery at first symptom than
after routine and early surgery

The natural history of this malformation remaining unknown

DECISION-MAKING:
Absence of deficits


acceptable X Strict protocol of surveillance

Prophylactic Surgery Operated only at first symptom.

DECISION-MAKING:
Absence of deficits


acceptable X Strict protocol of surveillance

(1) Thorough and multidisciplinary clinical
examinations, at referral, every 6 months until the
Prophylactic Surgery age of 2 years, then every year,
(2) Urodynamic studies at referral and every six
month until the age of the continence (grossly two
year of age) and later on at any doubt,
(3) MRI at diagnosis, at one year to assure that the
lipoma has not increased, and later on every five
years until growth is finished.

SURGERY:
Principles
• Surgery aims to untether the cord, decompress it if
necessary, spare the functional nervous tissue and
prevent from retethering.
• It must be conducted under optic magnification and
micro-instruments.
• In the case of lipoma of the conus, ultrasonic
aspiration and contact laser are extremely useful.
• Intra-operative neuro-physiological recording is
theoretically useful to distinguish functional roots
from fibrotic bands but it did not give the security
expected because stimulations were not permanent
and recording from sensory roots not totally
reliable, in particular from sphincterian rootlets.

SURGERY:
Surgery for lipoma of the filum
• It is a one-hour procedure.
• A small cutaneous incision is sufficient,
vertical or horizontal to put a distance
between it and the gluteal furrow.
• The dural sac is reached through an inter-
spinous approach between L5 and S1.
• A one-centimeter incision allows
recognition, isolation, division and
resection of 1cm of filum.
• It is frequent that the filum retracts
strikingly after its division.

SURGERY:
Surgery for lipoma of the conus
• The cutaneous incision is vertical on the midline, or
horizontal when the lipoma is sacral, to limit risks of
postoperative infection.
• The resection of the subcutaneous lipoma is, in our
opinion, better minimal than total or subtotal to
prevent the creation of a dead space in which the
CSF could collect postoperatively.
• A laminectomy of the lowest or the two lowest
normal laminae is, in general, necessary to expose
the normal dura and the upper part of the lipoma.
• The dural incision is made rostro-caudal,
circumscribing the stalk of the lipoma.

SURGERY:
• The division of the subdural adhesions is crucial
both to expose the lateral aspects of the lipoma
and the underlying roots and to free the cord.
• The severity of the adherences, a missing dura
replaced by musculo-aponeurotic bundles, or
shortness of roots may be such that freeing of the
cord is impeded, at least partially.
• The degree of removal of the intraspinal lipoma that
“total” removal in an attempt to reach the fibrotic
interface is doable, but carries the intrinsic risk of
injuring the posterior columns, provoking severe
and durable pain, trophic ulcers or bladder
paralysis.

SURGERY:
• For that reason, we no longer advocate as
complete a resection as we did in the past,
especially as we have not found any correlation
between postoperative results and degree of
removal.
• Removal of the lipoma must be cautious and
necessarily limited in the case of a posterolateral
insertion of the lipoma because of the presence of
intra-lipomatous roots.
• The closure of the placode is not always possible,
depending upon its shape and the volume of
residual lipoma.
• In our experience, the closure edge to edge of the
placode does not prevent from postoperative re-
adhesion but facilitates an eventual second
surgery.

SURGERY:
• The drainage of a terminal syrinx by means of a
myelotomy or a drain is not recommended, as we
found no correlation between patient’s pre- and
postoperative status, and the presence or the size
of a syringomyelia.
• Many syrinx regress postoperatively.
• The enlargement of the dural sac has been
recommended to prevent postoperative retethering.
• Many prosthetic materials have been proposed,
including Gore-Tex more recently, but none has
proved to be better than the other.
• None prevents from postoperative adherences or
reduces the risk of late postoperative deterioration.

SURGERY:
• For these reasons, we ceased to systematically
enlarge the dural sac.
• In our patients, re-adherences were constant
whatever the technique used. Interestingly, of these
patients, only a few developed further symptoms
related to a tethered cord syndrome, illustrating the
fact that fixed cord and tethered cord are different
concepts.
• The closure of the dura, with or without
enlargement, is never waterproof because of
constant dural anomalies.
• It may also be difficult or impossible when the dura
is largely missing, obliging to fix the edges of the
dura or of the duroplasty to the paraspinal muscles.
• Postoperatively, knowing the frequency of
temporary mictional difficulties, we recommend
leaving in place a urinary catheter for 2–3 days.

The lipomatous mass is dissected
Preoperative view all around

Interface between the Postoperative view
lipoma and spinal cord

OUTCOME:
Long-term postoperative outcome of
symptomatic patients
• It is frequently said that preoperative
deficits rarely regress postoperatively.
• This is one of the main arguments in favor
of preventive surgery.
• This is clearly not our experience where
only clubfoot, scoliosis and congenital
deficits never regressed.
• Pain usually totally disappears.
• For the rest, the long-term results depend
upon the type of lipoma.

OUTCOME:
Long-term postoperative outcome of
symptomatic patients
• In lipomas of the filum:
• Results are excellent.
• 41% of the patients were cured, 12% improved, and
47% stabilized.
• In lipomas of the conus:
• Results tended to erode with time.
• The percentage of patients worse than before
surgery increased from 9% at one year to 29% at
more than 5 years.
• The outcome actually depended upon the immediate
postoperative results. (Most of those who clearly
improved at one year remained improved.)
• Many of those who apparently stabilized or suffered
from transient postoperative complications
deteriorated with time.
• 70% of the patients took advantage of the surgery
being either improved or stabilized.

OUTCOME:
Long-term outcome of preventive
surgery in asymptomatic patients
• The outcome differs according to the type of lipoma:
• In lipomas of the filum:
• Results are as excellent as in symptomatic
patients
• In lipomas of the conus:
• Results erode with time, due to retethering, and
underlying myelodysplasia
• Patients with minor myelodysplasia and severe
retethering have good chances to be improved
or even cured surgically
• Those with severe myelodysplasia, will probably
not improve or even continue to worsen.

OUTCOME:
Long-term outcome of conservative
treatment in asymptomatic
lipomas of the conus
• The spontaneous long-term history of
asymptomatic lipomas of the conus parallels
the long-term outcome after “preventive”
surgery.
• 30% asymptomatic patients treated
conservatively developed symptoms in a 10
year follow-up.

OUTCOME:
Re-operations
• Re-operations are always difficult and
detethering often limited.
• There is a consensus in favor of a first redo
surgery in the case of spontaneous
deterioration following a first surgery.
• Further re-operations are more difficult to
indicate.
• If a first reoperation is usually beneficial, the
same cannot be said about further surgeries.

HOW TO AVOID COMPLICATIONS:
SURGICAL COMPLICATIONS
• In lipoma of the filum:
• Surgery is benign in nature and the patient
discharged at day 3–5.
• The incidence of complication is quasi nil.
• In lipoma of the conus surgery (more risky):
• Local complications (25%)
• The subcutaneous meningocele is the most
frequent, often complicated by skin disunion,
CSF leak and infection.
• Its treatment implies compressive bandages and
repeated punctures to apply the skin to the
underlying tissues.
• Reoperations to close the fistula were necessary
in 3% of patients.

HOW TO AVOID COMPLICATIONS:
SURGICAL COMPLICATIONS
• In lipoma of the conus surgery (more risky):
• Transient neurological complications (7.5%)
• Urinary and motor deficits were the most
common,
• They generally cleared up in a few weeks as
EMGs and urodynamic studies normalized.
• Pain rarely needed aggressive treatment
• Permanent neurological complications (3.4%)
• Sphincter-related –Urinary retention more
common than incontinence
• Motor deficits were unilateral, distal and
moderate
• Trophic ulcers are exceptional, probably
consecutive to injury of the interface and the
posterior columns.

PREVENTION OF POSTOPERATIVE
COMPLICATIONS
• To leave the largest possible volume of
subcutaneous lipoma in order to prevent the
subcutaneous meningocele
• To reduce the volume of the residual lipoma
later on by lipo-aspiration
• To leave a few millimeters of lipoma over the
interface in order to not injure the posterior
columns
• To accept to not achieve a total untethering of
the cord as soon as roots are unrecognizable
among adherences.

CONCLUSIONS
• Lipomas must distinguish lipomas of the fi lum from
those of the conus. These two lesions have almost
nothing in common from both clinical and therapeutic
aspects.
• To the simplicity and benignity of the first type, one
must oppose the complexity and frequent severity of
the second one.
• The second conclusion is that treatment of
asymptomatic lipomas of the conus is no more
acceptable, implying risks and not improving the natural
prognosis of the pathology.
• “Preventive” surgery in this field remains a dream. The
error has been to advocate this concept before knowing
the natural history of lipomas and weighting operative
advantages.

CONCLUSIONS
• In addition to treatment recommendations, we should
emphasize the fact that fixed cord does not mean
tethered cord.
• Following surgery, 100% of the patients develop new
adherences tying up again the cord to the dura but,
among them, only a few will deteriorate.
• The same reasoning should be held when a lipoma is
diagnosed in absence of deficits.
• The presence of a cord attached to a lipoma and
surrounding structures does not mean that the cord is
necessarily tethered and at risk of dysfunction.
• We should also remind that tethering might not be the
only factor causing neurological worsening since some
patients aggravate ineluctably whatever has been done
surgically.
• This certainly suggests that surgery does not
ameliorate all of the relevant pathophysiological factors.

Lipomyelomeningocele

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