Protocol for Management of Split Cord Malformations

CHAPTER 12

Vivek Tandon, Harish Chandrappa, and Ashok K. Mahapatra

Table of Contents

■ Introduction

■ Clinical Presentation

■ Classification

■ Investigations

■ Management

■ Role of Neuromonitoring

■ Postoperative Care

■ Complications, Prevention, and Their Management

CHAPTER
12

Protocol for Management of Split Cord Malformations

Vivek Tandon, Harish Chandrappa, and Ashok K. Mahapatra

Introduction

Split cord malformations (SCMs), being occult spinal dysraphisms, are rare congenital anomalies of the spinal cord. With advent of MRI and rising awareness of physicians, pediatricians and orthopedicians, an increasing number of asymptomatic or occult malformations are being diagnosed and referred to the neurosurgeons.

Clinical Presentation

Patients may present with various symptomatology of either deformity of back, limb deformity or progressive neurological deficits including tethered cord syndrome.²^,²^,²^,²^,²

Patients may also be asymptomatic, with only cutaneous stigmata.²^,²

Adults may present only with backache (Box 12.1).²

Box 12.1 Various symptoms/signs of SCM

•Backache

•Progressive neurological deficits

•Orthopedic syndrome

•Urinary disturbances

•Sensory disturbances

•Asymptomatic:

◇Cutaneous stigmata

◇Hypertrichosis/Faun’s tail

◇Capillary hemangioma

◇Subcutaneous lipoma

◇Skin tags

◇Dermal sinus

◇Sacral dimple

Classification

Pang classified the SCM into type I and II.² Type I was further classified into four types by Gupta and Mahapatra, based on the relation of the bony spur to the cord and risk of operative injury to the cord and, in turn, the risk of postoperative neurological deficits (Table 12.1).²

Fig. 12.1 (a) Type I split cord malformations (SCM)—T2W MRI axial section, showing two hemicords enclosed in two separate subarachnoid space, with an hypointense bony spur. (b) Type II SCM—Two hemicords enclosed in a single subarachnoid space.

Table 12.1 Classification of SCM
SCM type	Anatomic	Radiographic	Location
I	•Two hemicords in two dural sleeves separated by a midline bony spur. •Hypertrophic laminae are often fused to adjacent levels.	•MRI—Two hemicords with two separate dural sleeves (subarachnoid space) separated by a bony spur (Fig. 12.1a). •CT—Bony spur with intersegmental fusion and spina bifida.	Typically lumbar.
II	Two hemicords in a single dural sleeve. Hemicords are separated and tethered by a fibrous band attached to the dura.	Two hemicords with a single subarachnoid space on T2W MRI, with or without a fibrous septum (Fig. 12.1b).	May occur anywhere along the spinal axis.

Abbreviation: SCM, split cord malformation.

Type I could be further classified as follows (see also Fig. 3.5 in Chapter 3):

•Type Ia: Bony spur in the center with equally duplicated cord above and below the spur.

•Type Ib: Bony spur at the superior pole with no space above and a large duplicated cord lower down.

•Type Ic: Bony spur at the lower pole with a large duplicated cord above.

•Type Id: Bony spur straddling the bifurcation with no space above or below the spur.

Investigations

X-ray: May detect the occult spina bifida, abnormal curvature of the spine. Also, helps in identification of bony landmarks, and a preoperative Marker X-ray may be used to reduce operative time and radiation exposure in the operating room (OR).²^,²

MRI: It is the most common and usually the first investigation of choice for the diagnosis of SCMs. The typical feature is the presence of two hemicords, duplicated or in a single dural sheath as seen on T1W and T2W images, respectively. Presence of a bony spur may also be visualized.

Also, MRI can show other tethering elements like lipoma, fatty filum, dermal sinus, neuroenteric cyst, or dermoid. Because multiple tethering elements may be present, all patients with suspected spinal dysraphism and patients with scoliosis should get an axial MRI of whole spine to rule out any split or tethering elements elsewhere 2 (Fig. 12.2).