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30.2 Physical Examination

Patients with CM1 present with symptoms caused by hydrocephalus, syringomyelia (Chap. 31), or compression of the brainstem. Nevertheless, patients may be asymptomatic, and scoliosis may be the only symptom; magnetic resonance imaging to check the spinal cord and the cranio-cervical junction must be requested for all children with infantile idiopathic scoliosis. CM1 tends to be diagnosed in the second or third decade of life. The most common symptom is a suboccipital headache and neck pain, followed by mostly unilateral sensorimotor decits. Characteristic signs in the physical examination are downbeat nystagmus, hyperactive reexes with atrophy or weakness, gait disturbance, and cerebellar signs like ataxia (Video 30.4).

Patients with CM2 present with symptoms caused by brainstem compression, hydrocephalus, myelomeningocele, and lower cranial nerve dysfunction. Onset is usually in childhood and uncommon in adulthood. Neonates tend to develop severe brainstem dysfunction with rapid neurological deterioration (Video 17.6), whereas symptoms in older children are rarely as severe. Signicant ndings in the physical examination are swallowing difculties with aspiration, respiratory distress, apnea, stridor, and signs like downbeat nystagmus and opisthotonus. Weakness progressing to quadriparesis may occur (Video 30.4).

30.3 Imaging

The neuroradiological investigation is crucial to diagnose patients with Chiari malformation and to rule out any associated anatomical pathologies.

• Magnetic resonance imaging (MRI) of the brain and cervical spine is the diag-

nostic test of choice.

• Cerebrospinal uid ow study (Cine MRI) using a variety of MRI techniques to

visualize the CSF ow through the foramen magnum, which is typically impaired.

• Computed tomography (CT) and CT-myelography: Myelography is used when

MRI is not possible or unavailable. Due to bony artifacts, unenhanced cCT is

decient in the evaluation of posterior fossa pathologies.

• Ultrasonography is widely used as a routine examination during the prenatal

examination to follow up the intrauterine development and to detect congenital

anomalies such as neural tube defects or ventriculomegaly.

• Skull lms may demonstrate disproportion from hydrocephalus in infants.

30.4 Differential Diagnosis

Table 30.1 outlines differential diagnosis (Table30.1; adapted after [2]).

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Table 30.1 Differential diagnosisbetween CM1 and 2

Findings Caudally dislocated

structures

Caudal dislocation of the medulla

Syringomyelia May be present May be present Spina bida

(myelomeningocele) Hydrocephalus May be present Present in most Age of presentation Adolescent/adult Infancy Symptoms Suboccipital headache, cervical

MRI T2 sagittal

Chiari malformation type 1

Cerebellar tonsils Cerebellar hemispheres, vermis,

Unusual Yes

May be present Present in most

pain

Chiari malformation type 2

tonsils, pons, medulla, fourth ventricle

Hydrocephalus and brainstem/ lower cranial nerve dysfunction: swallowing difculties, respiratory distress, apnea, stridor, downbeat nystagmus

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30.5 Treatment Options

In symptomatic patients with CM1, early surgical posterior fossa decompression (PFD) is recommended since patients respond best when operated early (<2years after onset [3]). Asymptomatic patients or patients with stable long-lasting symptoms may be observed and operated on when they become symptomatic or when showing signs of deterioration. However, when syringomyelia is present in asymptomatic patients, most neurosurgeons recommend surgical intervention.

In symptomatic patients with CM2, PFD is recommended. In the presence of hydrocephalus, implantation of a shunt system is recommended before PFD as soon as the patient can tolerate surgery. In severe cases with feeding difculties, respiratory insufciency, and apnea, patients need ICU management. If patients develop stridor due to laryngeal palsy, temporary tracheostomy must be considered.

Suboccipital craniotomy with C1 (sometimes C2/C3) laminectomy with or without duraplasty and tonsillar resection to decompress the cervicomedullary junction, reestablish the CSF ow, and reduce the size of the syrinx is the surgical treatment

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of choice. The general surgical technique of PFD is shown in the pictures below, from top left to bottom right(Fig. 30.1): prone position in Mayeld clamp and exion of the neck(a); midline skin incision from C4 spinous process to inion(b); incision of fascia and preparation of the muscle(c); preparation of occipital bone(d); bone removal above the foramen magnum 3×4cm and laminectomy of C1 (e, f).

Then open the posterior atlantooccipital membrane and cut dural contraction bands, followed by splitting and resection of the outer layer of the dura(Fig. 30.2).

In severe cases, a duraplasty with dural patch graft +/− shrinkage of tonsils can be performed (PFDD). The procedure of duraplasty is shown below from left to right(Fig. 30.3): wide Y-opening of the dura (beware of inferior sagittal sinus; keep arachnoidal layer intact); suture of the patch graft (autograft like fascia or galea patch/xenograft/synthetic substitute).

PFD without duraplasty produces comparable clinical and radiological outcomes and is associated with a lower risk of complications compared to PFDD (pain,

de f

Fig. 30.1 Posterior fossa decompression (PFD) by suboccipital craniotomy:(a) Prone position, (b) Midline marking of the incision from C4 spinous process to inion, (c) Skin and fascia incision and preparation of the muscle, (d) Preparation of occipital bone, (e) Bone removal above the foramen magnum 3 x 4 cm, (f) Laminectomy of C1

Fig. 30.2 Dissecting and cutting the posterior atlantooccipital membrane

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abc

Fig. 30.3 Duraplasty with dural patch graft(PFDD):(a) Y-shaped opening of the dura, (b) Intact arachnoidal layer after opening the dura, (c) Dural closure using patch graft

Fig. 30.4 Posterior Fossa Decompression (PFD) with suboccipital craniotomy and laminectomy of C1 and intact dura. Illustration by Kimberly Ohm

morbidity, and CSF stulas) [4]. Therefore, PFD with closed dura should be preferred to PFDD (Fig.30.4).

In case of ventral brainstem compression, some authors recommend an additional transoral clivus-odontoid resection [3].

30.6 Expected Outcomes

In general, the postoperative outcomes are considered to be good in symptomatic older children and adults. Successful interventions with almost complete remission of symptoms have been reported; spontaneous regression of thoracic infantile

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scoliosis can be observed in some patients if decompression is performed early enough, before the pubertal growth spurt.

In CM1, the pain usually improves signicantly after surgery with the most favorable results in patients with cerebellar symptoms, whereas weakness is less responsive [5]. Symptoms lasting longer than two years are correlated with worse outcomes [3]. In CM2, 2/3 of patients showed a (near-) complete resolution of symptoms, whereas 20% had no benet [6]. The most important prognostic factors are preoperative decits and rapidity of worsening with respiratory arrest and laryngeal palsy being associated with a worse outcome.

30.7 Potential Complications

General surgical complications include CSF leak, subdural hygroma, wound infection, meningitis/ventriculitis, vascular injuries, and hydrocephalus.

Specic surgical complications related to the posterior fossa decompression include cerebellar herniation through the craniotomy with recurrence of symptoms and brainstem injury/stroke.

Some patients can develop kyphosis at the craniocervical junction, which can be prevented by simultaneous posterior craniocervical junction instrumented fusion.

30.8 What Should Patient andFamily Know?

Patients with CM1 without symptoms need follow-up; when developing symptoms, surgery is recommended within two years after onset with good postoperative results [3]. Symptomatic patients with CM2 need surgery with postoperative results depending on the severity of decits and the rapidity of deterioration.

Further Readings

1. Iskandar BJ, Hedlund GL, Grabb PA, Oakes WJ.The resolution of syringohydromyelia with-

out hindbrain herniation after posterior fossa decompression. J Neurosurg. 1998;89(2):212–6.

2. Carmel PW. Management of the Chiari malformations in childhood. Clin Neurosurg.

1983;30:385–406.

3. Dyste GN, Menezes AH, VanGilder JC.Symptomatic Chiari malformations. An analysis of

presentation, management, and long-term outcome. J Neurosurg. 1989;71(2):159–68.

4. Jiang E, et al. Comparison of clinical and radiographic outcomes for posterior fossa decom-

pression with and without duraplasty for treatment of pediatric chiari i malformation: a pro-

spective study. World Neurosurg. 2018;110:e465–72.

5. Cabraja M, Thomale U-W, Vajkoczy P.Spinal disorders and associated CNS anomalies—teth-

ered cord and Arnold-Chiari malformation. Orthopade. 2008;37(4):347–55.

6. Pollack IF, Pang D, Albright AL, Krieger D.Outcome following hindbrain decompression of

symptomatic Chiari malformations in children previously treated with myelomeningocele clo-

sure and shunts. J Neurosurg. 1992;77(6):881–8.

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BurakKaraaslan andAlpÖzgünBörcek

31.1 Definition

Spinal dysraphism (SD) is an umbrella term that includes congenital midline neural tube defects. Midline closing of bone, neural, or other mesenchymal tissue is defective. Spinal dysraphism can be classied as open type (spina bida aperta; SBA) and closed type (spina bida occulta; SBO) dysraphism. Open-type dysraphism includes hemimyelocele, meningocele, myelomeningocele, and hemimyelomeningocele. Closed dysraphism includes lipomyelomeningocele, dermal sinus, diastematomyelia, slit notochord, tight lum terminale, myelocystocele, neurenteric cyst, and developmental tumors such as spinal lipomas (Table31.1).

31.2 Physical Examination

Clinical symptoms of SBO are often due to tethering of the spinal cord. Tethering of the spinal cord may cause back pain, perineal sensation loss, myelopathy of lower extremities, incontinence, and neurogenic bladder (Video 31.4).

Spinal bida occulta can be associated with a cutaneous stigma (hypertrichosis, dimple, capillary hemangiomas, or sinus tract; Fig.31.1).

SD is a congenital spinal malformation, so its occurrence accompanied by other congenital system anomalies is not rare. The most common accompanying

Supplementary Information The online version contains supplementary material available at (https://doi.org/10.1007/978- 3- 030- 80356- 8_31).

B. Karaaslan · A. Ö. Börcek (*) Division of Pediatric Neurosurgery, Gazi University Faculty of Medicine, Ankara, Turkey e-mail: burakkaraaslan@gazi.edu; alpborcek@gazi.edu.tr

https://doi.org/10.1007/978-3-030-80356-8_31

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Table 31.1 Classication of spinal dysraphism

Spina bida occulta

Spina bida aperta

•Myelomeningocele •Lipomyelomeningocele Simple

•Meningocele •Lipomyelocele •Spinal lipoma

•Hemimyelocele • Terminal myelocystocele •Tight lum terminale

•Hemimyelomeningocele •Meningocele •Dermal sinus

With subcutaneous mass Without subcutaneous mass

B. Karaaslan and A. Ö. Börcek

•Persistent terminal ventricle

Complex

Disorders of midline notochordal integration

•Diastematomyelia

•Neurenteric cysts Disorders of segmental

notochordal formation

•Caudal agenesis

•Segmental spinal dysgenesis

Fig. 31.1 Patients’ photographs demonstrate different types of cutaneous stigmata and orthopedic anomalies associated with spinal dysraphism. (GUFM Division of Pediatric Neurosurgery archive)

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Fig. 31.2 (a) T2-weighted sagittal MRI images of an SCM patient. (b) Axial CT scan shows a midline osseous spur

congenital anomalies with SD are urologic problems. Studies showed that nearly 25% of SD patients have urologic pathologies. Also, different types of cardiovascular, renal, and skeletal (particularly in lower extremities) malformations are reported.

31.3 Imaging

Computerized tomography is helpful in the assessment of bony malformations (Fig.31.2). Magnetic resonance imagining (MRI) is the gold standard radiological modality. Complete spinal and cranial MRI scanning is mandatory for these patients, because multiple congenital malformations are not rare in these patients.

31.4 Treatment Options

Surgical treatment is indicated as soon as possible for open-type spinal dysraphism. Local infection and central nervous system infection are the main potential risks for these patients. The main surgical aim is to close the spinal opening which exposes the neural tissue to infectious risks.

Clinical symptoms of occult spinal dysraphism are usually due to tethering of the spinal cord. Neurological decits usually progress slowly and coincide with body growth. Surgical untethering is indicated as soon as possible for patients with neurological ndings. Surgical treatment is aimed to release the tethering of the spinal cord.

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There is a debate in the literature about the management of asymptomatic SBO as spinal lipomas, including lipomyelomeningocele. Some studies advocate early prophylactic untethering surgery. However, Kulkarni et al. reported follow-up results of conservative management of asymptomatic spinal lipomas. This study showed no statistical difference in the follow-up result of neurological deterioration between early surgery and conservative management.

Since most of the closed-type patients have subtle neurological problems, surgery in those patients puts them at great risk for further deterioration, so every precaution should be exercised during the surgery of those patients. Intraoperative neuromonitorisation (IONM) is the most important of those measures. Whenever possible, surgeons should rely on IONM both for their (for medicolegal aspects) and patients’ safety.

B. Karaaslan and A. Ö. Börcek

31.5 Expected Outcomes

The most important prognostic parameter for symptomatic SBO is early diagnosis and treatment. Because severe neurological decits may not be reversible after surgery. On the other hand, the most important prognostic parameter for SBA is the location of the defect and related level of the neurological decit. Low-level lesion location and good spontaneous movement of lower extremities have a good functional outcome.

31.6 Potential Complications

Hydrocephalus is usually seen in SBA patients. CSF shunting is usually necessary. Other systemic disorders associated with SBA are vertebral deformities, genitourinary and gastrointestinal dysfunctions.

Spinal deformities, such as scoliosis, can be seen with spinal dysraphism. Scoliosis is the result of spinal cord tethering. So surgical correction of scoliosis without untethering the spinal cord will be a disaster.

Latex hypersensitivity is commonly seen in spina bida aperta, especially in myelomeningocele patients. Frequent and early exposure to latex products is suspicious. Latex-free surgical instruments should be used to avoid latex allergy for these patients.

31.7 What Should Patient andFamily Know?

Although surgical closure of SBA and surgical untethering of symptomatic SBO is usually necessary, spinal dysraphism is a congenital embryological disorder. No single intervention is expected to correct all of the problems in a particular patient. Anatomical, urological, cosmetic, and neurological problems require different management techniques and lifelong medical follow-up with a multidisciplinary team is

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mandatory. Prevention plays an important role; in particular, folic acid and folates supplementation before conception have been proven useful to prevent congenital midline neural tube defects.