Newer perspective in spina bifida: Limited dorsal myeloschisis

Abstract

Limited Dorsal Myeloschisis (LDM) is a relatively newly described entity in the spectrum of spinal dysraphism. Although considered rare, more cases are getting recognised with advancements in imaging technologies. We present a series of seven cases of paediatric spinal LDMs that were successfully managed surgically.

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Wadia Journal of Women and Child Health • Volume 1 • Issue 2 • September-December 2022 | 72 Wadia Journal of Women and Child Health • Volume 1 • Issue 2 • September-December 2022 | 73
Wadia Journal of Women and Child Health • Volume 1 • Issue 2 • September-December 2022 | 72 Wadia Journal of Women and Child Health • Volume 1 • Issue 2 • September-December 2022 | 73
Case Series
Newer perspective in spina bida: Limited dorsal
myeloschisis
Pawan Chawla1, Chandrashekhar E� Deopujari1, Uday Andar1
1Department of Neurosurgery, Bai Jerbai Wadia Hospital for Children, Mumbai, Maharashtra, India�
INTRODUCTION
Spinal dysraphic malformations are caused by embryogenic defects of primary or secondary
neurulation leading to inability to form a proper central neuraxis� First described in 1993,
Limited Dorsal Myeloschisis (LDM) is a relatively new entity in the spectrum of spinal
dysraphism that was initially thought of as meningocele�[1] Initially considered a rare entity,
increasing number of cases are emerging nowadays due to readily available, advanced imaging
technologies suggesting that it is not such a rare entity� Pang et al� (2010) classied LDMs into
saccular and at types�[2] True LDMs causing tethering of cord have been identied in all regions
of the spinal neuraxis with maximum incidence at the lumbar level�
We present an illustrative series of 7 cases of paediatric spinal LDMs that were successfully
managed by surgical approach at our centre�
CASE SERIES
Case 1
A 15-month-old girl presented with history of swelling over the neck since birth� e skin was
very thin and fragile over the lesion, but was intact� Clinical examination revealed a solitary
saccular swelling over the cervico-dorsal region measuring 8x9 cm� e cranial outermost
portion of the swelling had a reddish, translucent, dome-like structure that was bulging out like
a cap and was covered with a membrane-like structure with parched skin all around but with no
defect� Base of the swelling was formed by thickened skin that was stretched with dilated veins
ABSTRACT
Limited Dorsal Myeloschisis (LDM) is a relatively newly described entity in the spectrum of spinal dysraphism�
Although considered rare, more cases are getting recognised with advancements in imaging technologies� We
present a series of seven cases of paediatric spinal LDMs that were successfully managed surgically�
Keywords: Spina bida, Limited dorsal myeloschisis, Saccular
How to cite this article: Chawla P, Deopujari CE, Andar U� Newer perspective in spina bida: Limited dorsal myeloschisis� Wadia J Women Child Health
2022;1(2):72-7�
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behalf of Wadia Journal of Women and Child Health
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Wadia Journal of Women and Child Health
*Corresponding author:
Pawan Chawla,
Department of Neurosurgery,
Bai Jerbai Wadia Hospital
for Children, Mumbai,
Maharashtra, India�
cus_pwn@yahoo�co�in
Received : 08July 2022
Accepted : 18August 2022
Published : 17November 2022
DOI
10�25259/WJWCH_4_2022

Chawla, et al.: Newer perspective in spina bida
Wadia Journal of Women and Child Health • Volume 1 • Issue 2 • September-December 2022 | 72 Wadia Journal of Women and Child Health • Volume 1 • Issue 2 • September-December 2022 | 73
Wadia Journal of Women and Child Health • Volume 1 • Issue 2 • September-December 2022 | 72 Wadia Journal of Women and Child Health • Volume 1 • Issue 2 • September-December 2022 | 73
suggesting chronicity of the lesion� e swelling had a broad
fundus with a narrow neck palpable between the spinous
processes of C6 and T2� e swelling was non-tender, so
in consistency, and uniformly transilluminating with cough
impulse on crying� On examination, the patient did not have
any weakness of the upper or lower limbs [Figure1a]�
MRI showed a large cystic sac-like structure measuring around
9�5 x 8�3 x 9�6cm, protruding posteriorly through a defect at C7-
D1 level� e spinal cord was tethered at that level posteriorly
through a linear T2 hypointense structure, seen attaching the
dorsal surface of the cord with the surface of the sac, likely a
broneural stalk suggestive of a saccular LDM� Few ill-dened
T1 hyperintense areas were seen within the sac suggestive of
a fatty component� Brain screening was suggestive of small
crowded posterior fossa with cerebellar tonsillar herniation
with mild supratentorial hydrocephalus [Figure1b]�
She underwent surgical excision of the LDM� An elliptical
incision was marked over the conuence of healthy and non-
healthy skin� e meningocele sac was opened and the stalk
was dissected from the inner wall of meningocele sac� Aslit
incision was taken over the sac releasing the cerebrospinal
uid (CSF)� Release of the CSF led to decrease in the size of
the sac, aiding in easy dissection [Figure1c]�
e neck of the sac could be seen passing through the
laminar defect towards the dura� Normal dura was identied
cranial and caudal to the neck� Dura was opened and the
insertion of the broneural stalk inserting into the dorsal
sac was identied� e sac was opened from above and the
broneural stalk was resected from the dorsal thecal sac
[Figure1d]�
Post-operative period was uneventful� No worsening or new
neurological onset decit was noted�
Case 2
A 7-month-old girl presented with a swelling over the
lumbosacral region since birth� On examination, a solitary
lumbosacral LDM was noted with normal bilateral lower limb
movements� e skin over the swelling was very thin but intact
with brilliant transillumination� Fibroneural stalk could be seen
very clearly on MRI and also during the surgery� e patient
underwent surgical excision of the LDM with an uneventful
post-operative period [Figure2]�
Case 3
A 5-month-old boy presented with a swelling over the
lumbar region since birth� On examination, a solitary lumbar
LDM was noted over the back along with bilateral club foot�
e skin over the swelling was intact but scarred� Attachment
of the broneural stalk to skin could be clearly elicited during
Figure1: (a) A solitary saccular swelling over the cervico-dorsal region, (b) MRI was suggestive of a large cystic sac-like structure protruding
posteriorly through the defect at C7-D1 level, (c) an elliptical incision was marked over the conuence of healthy and non-healthy skin, and
(d) insertion of the broneural stalk inserting into the dorsal sac�
b
a
dc

Chawla, et al.: Newer perspective in spina bida
Wadia Journal of Women and Child Health • Volume 1 • Issue 2 • September-December 2022 | 74 Wadia Journal of Women and Child Health • Volume 1 • Issue 2 • September-December 2022 | 75
transillumination� CSF - lled sac was carefully dissected
from the surrounding tissues during surgery� e patient had
an uneventful post-operative period [Figure3]�
Case 4
A 7-month-old boy presented with a solitary lumbar LDM
with normal bilateral lower limb movements� e skin
over the swelling was thin but intact� Large CSF - lled
membranous dome was carefully dissected from the
surrounding tissues during surgery� Surgical excision of the
LDM was done using intraoperative neuromonitoring� Post-
operatively, the boy recovered without any complications�
[Figure4]�
Case 5
A 5-month-old boy presented with an unusual cauliower-
shaped lumbar LDM with normal bilateral lower limb
movements� e patient underwent surgical excision of the
LDM under intraoperative neuromonitoring with uneventful
post-operative recovery [Figure5]�
Case 6
A 13-year-old girl came to us with a solitary lumbar LDM
with weakness of both (le > right) lower limbs� e skin
over the swelling was thickened� MRI showed a solitary at
L2 level LDM associated with split cord malformation (SCM)
Type2 and dorsolumbar scoliosis� e long broneural stalk
usually seen in saccular type is absent in these children who
have a at LDM� e patient underwent surgical excision
of the LDM under intraoperative neuromonitoring with an
uneventful post-operative period [Figure6]�
Figure 2: A solitary lumbosacral LDM showing brilliant
transillumination with broneural stalk�
Figure3: A solitary lumbar LDM showing brilliant transillumination
with CSF-lled sac�
Figure4: A large solitary lumbosacral LDM showing a large CSF
lled membranous dome�
Case 7
A 7-month-old boy presented with a swelling over the nape
of neck since birth� On examination, a solitary cervical LDM
was noted with normal power in all four limbs� MRI showed
a solitary at C3-C4 level LDM� During surgery, the LDM
was excised in toto� e absence of any CSF - lled sac/tract
is notable [Figure7]�
DISCUSSION
LDM is a relatively newly recognized form of spina bida that
is characterized by a bro-neural stalk between the thecal sac
and the inner part of the skin�

Chawla, et al.: Newer perspective in spina bida
Wadia Journal of Women and Child Health • Volume 1 • Issue 2 • September-December 2022 | 74 Wadia Journal of Women and Child Health • Volume 1 • Issue 2 • September-December 2022 | 75
An LDM basically consists of a focal, closed, midline defect
and a bro-neural stalk�[2,3] It was initially described in 1993
by Pang et al, who later ascribed a better denition and a
classication system in 2010�[2]
LDMs are considered less severe, as compared to
myelomeningoceles, due to the relatively later occurrence of
embryologic defect in the process of primary neurulation�[4]
e absence of neural placode and the presence of closed skin
dierentiates it from a myelomeningocele� Most of the steps of
primary neurulation including elevation, infolding, and recognition
of the dorsal neural folds have happened in cases of LDM except
for the nal phase of fusion of the opposing neural folds�[5] is
incomplete fusion of neural folds leads to the formation of a bro-
neural stalk between the skin lesion and the spinal cord�
In the past, LDMs have been confused with myelomeningoceles,
meningocele and myelocystoceles� N� Muthukumar et al. (2007)
presented a series of 14 terminal and 9 non-terminal myelocystoceles
that were managed surgically�[6] A proper radiological evaluation
helps in dierentiating these overlapping entities� LDMs can vary
from being free of any neurological decit to causing complete
quadriplegia depending on their location and tethering of the
underlying cord� Preoperative absence of neurological decits can be
considered as a good prognostic marker in these cases�
Usually, LDMs are easily diagnosable at birth, however
they do not require immediate surgery like in cases of
myelomeningoceles� Surgery is typically advised aer the child
gains weight (more than 8 kg) or is at least 4 months old to be
able to tolerate anaesthesia and the surgical procedure with
ease� Immediate surgery is advised in cases of ruptured lesions
or in cases of identiable and worsening neurological decit�
LDMs can be saccular or at and can be associated with a plethora
of cutaneous and neural manifestations like craters, pits, lipomas,
hydrocephaus, syringomyelia, dermal sinus, split cords etc�[2]
Saccular LDMs usually have a membranous dome surrounded
by parched skin followed by thickened skin with dilated veins�
e prolonged pressure from the CSF might be responsible for
the formation of this membranous dome and parched skin� If le
unattended, this can lead to ulceration and necrosis�
Almost 50% of cervical LDMs were associated with
hydrocephalus in a study by Pang et al� MRI of the whole
neuroaxis is ideal in these cases to rule out any other anomalies�[7]
Figure6: Asolitary at L2 level LDM associated with SCM Type2
and dorsolumbar scoliosis (notice the absence of long broneural
stalk that is usually seen in saccular type)�
Figure5: An unusual cauliower-shaped lumbar LDM�

Chawla, et al.: Newer perspective in spina bida
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MRI helps to track down the extradural and intrathecal path of
bro-neural stalk thus guiding in the planning of surgery� e
tethering of the cord by the bro-neural stalk can be one of the
reasons for tonsillar herniation�
e aim of surgical intervention in these cases is to release
the tethering component and achieve good cosmetic results�
Saccular LDMs are more disguring as compared to at
lesions and hence are brought in for medical consult early�
Detethering is the principal aim of surgery to avoid any
future neurological decits� Intraoperative neuromonitoring
plays an important role in these surgeries because of almost
near normal limb movements in most cases� In absence of
detethering, there are higher chances of recurrence�
In our series, we used intraoperative neuromonitoring
and the bro-neural stalk could be successfully detethered
without any postoperative neurological decit in any of the
patients� One of the patients developed pseudomeningocele
at operative site and it was managed conservatively with
compressive dressing� ere are high chances of wound
dehiscence or infection in these cases because of thinned
out skin and dermis� In our series, 2 patients had supercial
wound infection, that was managed conservatively with
appropriate antibiotics and wound care� e literature
on LDMs is still very limited and there are a lot of critical
issues yet to be understood about this entity� is condition
has been confused with other dysraphic malformations in
the past and hence statistical data are scarce and an actual
estimate of its recurrence rate is limited�
CONCLUSION
LDM is a relatively new entity as compared to other dysraphic
malformations� Accurate identication and early surgical
intervention results in good outcome� However, a strict eye should
be placed on the follow-up of these cases to identify recurrences�
Declaration of patient consent
e authors certify that they have obtained all appropriate
patient consent�
Financial support and sponsorship
Nil�
Conicts of interest
ere are no conicts of interest�
REFERENCES
1� Pang D� Cervical myelomeningoceles� Neurosurge
1993;33:363-373�
2� Pang D, Zovickian J, Oviedo A, Moes GS� Limited dorsal
myeloschisis: A distinctive clinicopathological entity�
Neurosurg 2010;67:1555-79�
3� Lee JY, Chong S, Choi YH, Phi JH, Cheon JE, Kim SK, et al�
Modication of surgical procedure for “probable” limited
dorsal myeloschisis� JNeurosurg Pediatr 2017;19:616-9�
4� Pang D� Surgical management of spinal dysraphism� In:
Fessler R, Sekhar L editors� Atlas of Neurosurgical Techniques�
NewYork: ieme; 2006� p�729-58�
5� Schoenwolf GC� Observations on closure of the neuropores in
the chick embryo� Am J Anat 1979;155:445-66�
6� Muthukumar N� Terminal and nonterminal myelocystoceles�
JNeurosurg 2007;107:87-97�
7� Pang D, Zovickian J, Wong S, Hou YJ, Moes GS� Limited dorsal
myeloschisis: A not-so-rare form of primary neurulation
defect� Childs Nerv Syst 2013;29:1459-84�
Figure 7: Asolitary C3-4 level at LDM excised in toto� (Notice the absence of any CSF lled
sac/tract)�