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Case Desc ip ion o a Child wi h Righ -Sided To icollis and Se e ely Limi ed
Ac i e Ro a ion in he Ce ical Spine owa d he Righ Side due o Hypoplasia o
he S e nocleidomas oid Muscle on he Le Side
Anna Öhman*
Specialis in Pedia ic, Heal h and Rehabili a ion/Physio he apy, Uni e si y o Go henbu g, Go henbu g,
Sweden
Ci a ion: Anna Öhman. Case Desc ip ion o a Child wi h Righ -Sided To icollis and Se e ely Limi ed Ac i e
Ro a ion in he Ce ical Spine owa d he Righ Side due o Hypoplasia o he S e nocleidomas oid Muscle on
he Le Side. In Clinc Med Case Rep Jou . 2025;4(11):1-7.
Recei ed Da e: 22 No embe 2025; Accep ed Da e: 24 No embe 2025; Published Da e: 25 No embe 2025
*Co esponding au ho : Anna Öhman, Specialis in Pedia ic, Heal h and Rehabili a ion/Physio he apy,
Uni e si y o Go henbu g, Go henbu g, Sweden
Copy igh : © Anna Öhman, Open Access 2025. This a icle, published in In Clinc Med Case Rep Jou
(ICMCRJ) (A ibu ion 4.0 In e na ional), as desc ibed by h p://c ea i ecommons.o g/licenses/by/4.0/
ABSTRACT
A e e al a he age o 1.5 yea s, he child showed an ex eme di e ence in o a ion o he head be ween ac i e
and passi e mo ion owa d he igh side. He did no ac i ely o a e his head mo e han sligh ly o e a neu al
posi ion owa d he igh side bu he had ull ac i e ange o mo ion (AROM) owa d he le side. Passi e ange
o mo ion (PROM) was excellen in bo h o a ion and la e al lexion bila e ally.
He il ed his head owa d he igh side, and had s onge la e al lexo muscles on he igh side. As he e was no
limi ed PROM, his indica ed a igh -sided pos u al o icollis. Howe e , he ex eme p oblem o ac i ely
o a ing owa d he igh side was disconce ing.
A he age o six yea s, hypoplasia o he s e nocleidomas oid (SCM) muscle on he le side was e ealed. The
small amoun o muscle mass on he le side explained he ex emely limi ed ac i e o a ion owa d he igh
side. The SCM muscle on he le side o a es he head owa d he igh side.
Conclusion: When o icollis wi h good PROM is combined wi h unusually la ge p oblems wi h AROM in
o a ion, hypoplasia/aplasia o he SCM muscle mus be in es iga ed.
Keywo d: Hypoplasia; S e nocleidomas oid muscle; In an ; Child; Ce ical ac i e o a ion
ABBREVIATIONS
AROM: Ac i e ange o mo ion
CMT: Congeni al muscula o icollis
SCM: S e nocleidomas oid
MFS: Muscle unc ion scale
PROM: Passi e ange o mo ion
PT: Physical he apy
MRI: Magne ic esonance imaging
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INTRODUCTION
To icollis is a sign no a diagnosis, meaning asymme ical pos u ing o he head and ce ical spine.[1,2] The
SCM muscle is a wo-headed neck muscle whe e he uppe pa is a ached o he mas oid and he wo lowe
pa s a e a ached o he s e num and he cla icle. Asymme ic unc ion o he SCM muscle can gi e an
asymme ical head pos u e. The mos common cause o o icollis among in an s is congeni al muscula
o icollis (CMT).[3] In CMT he SCM muscle is con ac ed o ense and has s onge muscle unc ion on he
a ec ed side.[4,5,6] Ro a ion and la e al lexion can be measu ed wi h a big p o ac o [7,8,9,10,11] and muscle
unc ion examined using he muscle unc ion scale (MFS).[12,13] Howe e , o icollis can ha e o he causes han
a con ac ed o ense muscle.[14]
Muscula hypoplasia o aplasia is a a e phenomenon and is e y unusual in he SCM muscle.[15-18] In some
cases a pa o he SCM muscle is missing and in some cases he whole SCM muscle is missing.[15] An MRI is
used o con i m muscle aplasia.[19] Aplasia o he SCM muscle has been disco e ed in newbo ns[20,21] and in
adul hood o o he s (Singh 2014) o disco e ed a dissec ion a e dea h.[22,23] When hypoplasia o aplasia o he
SCM muscle occu s, he e is an imbalance in he neck ha causes he head o il o he side wi h a no mal SCM
muscle, wi h he head u ning o he opposi e side. This head posi ion can be in e p e ed as CMT i
hypoplasia/aplasia is no disco e ed. In CMT he head is il ed owa d he abno mal muscle and o a ed o he
opposi e side.
The mos known muscle when i comes o aplasia is he pec o al muscle.[24] Aplasia o he pec o al muscle is
cha ac e is ic o Poland synd ome.[25] Aplasia o he apezius muscle has been seen in h ee amily membe s
suppo ing he no ion o a gene ic link.[19] Absence o he whole SCM muscle o pa o i has been seen in an
in an , his a he and g and a he , also poin ing owa d a gene ic link.[26] Lung he nia ion due o aplasia o SCM
has been epo ed in wo in an s.[20,27] An MRI is used o examine he absence o muscles.[18]
CASE
A child e e ed o physical he apy (PT) due o o icollis a he age o 1.5 yea s. He had a mild il ing o his
head wi h la e al lexion owa d he igh side and a small o a ion owa d he le side. The e was excellen
PROM in bo h o a ion and la e al lexion bila e ally. The igh side was s onge han he le side, on he MFS
scale he go sco es o 3 and 1 (Table 1). He was diagnosed as ha ing igh -sided pos u al o icollis. Howe e , i
was ex emely di icul o him o o a e ac i ely owa d he igh side, when o a ing his head owa d he igh
side he u ned his whole o so.
Table 1: Measu es and es ima es o PROM, AROM and MFS o case a age 1.5 yea s
Func ion
Righ
Le
Passi e o a ion
>90°
>90°
Ac i e o a ion es ima ed
5-
10°
65°
Passi e la e al lexion, ea o shoulde
yes
yes
MFS sco es
3
1
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Due o a misunde s anding i was belie ed ha an MRI had been ca ied ou on his ce ical spine. La e i was
clea ha he MRI had been ca ied ou on he head o exclude c aniosynos osis, al hough he seemed o ha e
only mino de elopmen al plagiocephaly. This was no e iden when he go olde , his head shape was in he
no mal span.
A lo o exe cises o ac i e o a ion owa d he igh side we e es ed; his was a challenge o all as i was e y
con using why i was so ha d o him o pe o m ac i e o a ion owa d he igh side when he e was no
p oblem a all wi h PROM. A he age o 2.5 yea s, he la e al lexo s on he le side had become s onge bu
he e was s ill a mino head il owa d he igh . S eng h aining o he le side was con inued. A ou yea s o
age, his head was in midline and he could o a e his head be e o he igh bu no as well o he le . He was
gi en a b eak om PT and was ollowed up again a i e yea s o age. A he ollow-up, he il ed his head
owa d he igh again and had ob ious p oblems o a ing his head owa d he igh side wi hou o a ing his
o so. I could i s be su mised ha he SCM muscle had no g own in leng h bu he s ill had excellen PROM in
his ce ical spine. The p oblem o o a ing his head o he igh side had been a mys e y om he i s s a o PT
and di e en app oaches o exe cises, adjus ed o his age, we e adop ed. In passi e mo ion he e was no p oblem
a all o o a e his head 90° bila e ally. He could lie in supine posi ion on he examina ion able wi h his head
o e he edge, wi h his head es ing in he examine ’s hands o unbu den he weigh o he head. He could o a e
his head o abou 90° by himsel bila e ally.
A six yea s o age in Ap il 2024, muscle hypoplasia was disco e ed as he e was no isible s e nal head
a achmen o he SCM muscle on he le side (Figu e 1).
Figu e 1: A he age o six yea s lying on an examina ion able, when o a ing he head owa d he le side he e
was a clea ly isible s e nal muscula a achmen on he igh side (A). When o a ing he head owa d he igh
side he e was no isible muscula a achmen on he le side (B).
A con ac was aken wi h a plas ic su geon wi h long expe ience o o icollis. On pa en al ag eemen , a e e al
o examina ion was made. An MRI con i med hypoplasia o he SCM muscle on he le side. Repo a e he
MRI: “I was ha d o ollow he p oximal a achmen o he SCM muscle a p ocessus mas oideus.” A achmen
a he cla icle and s e num di e ed om he igh side, he muscle was abou 4 mm on he le side compa ed
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wi h 10 mm on he igh side. An MRI was also done as i was impo an o ule ou he absence o o he neck
muscles han he SCM. The o he muscles in he neck we e ound o be symme ical. I he e had been
hypoplasia o mo e muscles, i would ha e been necessa y o ule ou o he p oblems.
DISCUSSION
Hypoplasia o he SCM muscle on he le side explains his p oblems wi h o a ion owa d he igh side. The
s e nal pa o he SCM muscle on he le side o a es he head o he opposi e side. Less muscle mass on he le
side a ec s he abili y o o a e he head owa d he igh side. As muscle hypoplasia is a e, and e y a e in he
SCM muscle,[15-18] i s occu ence is unexpec ed. Cases wi h hypoplasia/aplasia may look di e en . F om he
cu en case i can be lea ned o keep hypoplasia/aplasia o he SCM muscle in mind when he e is an ex eme
disc epancy be ween AROM in o a ion and no limi ed PROM in he neck a all.
The disco e y o hypoplasia o he muscle helps o se easonable expec a ions and goals ha a e achie able. A
ealis ic plan o wha needs o do be done o keep he head in midline and ge he bes possible unc ion. Regula
pe iods o aining a e p obably unc ionally bene icial, keeping he le side as s ong as possible because o he
lowe muscle mass in he le SCM muscle. S a egies o si ua ions whe e less o a ion could a ec a si ua ion
could be implemen ed. Fo example, on a bicycle holding he handleba s, when looking o he igh i may be a
isk o u n he o so as his may u n he bicycle in olun a ily. Indi iduals may ha e o lea n o compensa e o
his. A a young age hey can s op he bicycle and look, a an olde age hey can use mi o s on he bicycle o see
people and ca s e c. on he limi ed side.
Some a icles desc ibe he disco e y o aplasia o he SCM muscle a e dea h du ing ana omy dissec ions.[22,23]
Fo o he s i has been disco e ed du ing he i s days o mon hs o li e.[15,21] I is unknown i he cases
disco e ed a e dea h had any p oblems; a discussion p obably no en e ed in o wi h he amilies as i would
ha e p esen ed an e hical dilemma. Howe e , pho os could ha e e ealed i hey had a il ing owa d he
opposi e side o he absen muscle o a o a ion owa d he missing muscle. I is unknown i some can keep he
head in midline e en wi h aplasia o he SCM muscle. Neglec ed CMT exis s[28] and i can be specula ed ha
he e a e p obably some mild cases o neglec ed hypoplasia/aplasia o he SCM muscle wi hou ob ious
p oblems. Singh a al ound a 56-yea -old wi h he absence o he SCM muscle. This man acco ding o himsel
expe ienced no p oblems, and he was no willing o pa icipa e in u he examina ion.[29]
I is impo an o exclude o he p oblems when aplasia o SCM is disco e ed. Ha oon and Be e ley ound
he nia ion due o aplasia o SCM in an in an one hou a e bi h,[20] and Bayne e al ound i in a young in an
ha needed su ge y a he age o 4 mon hs.[27]
Kuma e al desc ibed a ou -yea -old boy whe e he pa en s p e e ed PT as he mode o ea men .[15] The
cu en case is oo young o make his own decisions, and o he momen he pa en s p e e o con inue wi h PT.
Wi h aining and s a egies o compensa e he limi ed ac i e o a ion, his may be he bes solu ion.
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Only one case ha unde wen su ge y elease on he con ala e al SCM muscle o co ec o icollis is ound in
he li e a u e, all o he known cases seem o ha e been esol ed well enough wi h PT.[30] The pos ope a i e
ea men ecei ed by he child ha unde wen su ge y is no desc ibed.
The cu en case ained s eng h in ce ical la e al lexion on he le side wi h hypoplasia o he SCM muscle.
When he was doing a lo o aining his head was in midline. I no doing enough his head il eoccu ed and
aining had o be in ensi ied again. I is p e e able i su ge y can be a oided bu aining will s ill be needed
a e su ge y. The SCM muscle is abou 4 cm in in an hood and abou 14 cm a he age o 13 yea s.[31] I we
accep mo e han a ma ginal head il , he e may be a isk ha he heal hy muscle will unde go seconda y
sho ening o e ime gi ing p oblems in he u u e. Vaj amani e al ollowed a child om six mon hs o age o
se en yea s and did no ecommend su ge y as he adjus ed o a mild o icollis wi h no unc ional p oblems.[32]
CONCLUSION
I is impo an o check ha bo h s e nal and cla icula a achmen o he SCM muscle a e isible. Al hough he
absence o a muscle o pa s o a muscle is no expec ed, a e cases do exis . When o icollis wi h ex eme
disc epancy be ween AROM and PROM in o a ion in he ce ical spine exis s, hypoplasia/aplasia o he SCM
muscle mus be in es iga ed.
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