141

7Diseases of the Spinal Cord

Anatomical Fundamentals . .		. 141		Infectious and Inflammatory Diseases
The Main Spinal Cord Syndromes and Their				of the Spinal Cord . . .	150
Anatomical Localization . .		. 142		Syringomyelia and Syringobulbia .		. . 151
Spinal Cord Trauma . . .	145			Diseases Mainly Affecting the Long Tracts
Spinal Cord Compression . . .		146		of the Spinal Cord . . .	153
Circulatory Disorders of the Spinal Cord . . .			148	Diseases of the Anterior Horns . . .		154

Anatomical Fundamentals

The spinal cord is the component of the central nervous		in the white matter, fiber pathways leading from the
system that connects the brain to the peripheral nerves.		brain to the periphery and vice versa;
It contains:		in the gray matter, an intrinsic neuronal system con-
		sisting of:

1

2

3

I-1

4

5

6

7

8

1

2

3

4

5

6 I-2 7 8 9 10 11 12 1

2

I-3 3

4

5

1

2 I-4 3

4

5

I-5

	1	1
C2	2	2
C3	3	3
	4
C4			4
	5
C5	6		5
C6	7		6
	8
C7			7
	1
T1		2	1
	2	3		2
			4
	3			3
			5
	4
			6	4
	5
			7	5
	6
			8
	7			6
			9
	8			7
			10
	9
			11	8
	10
			12	9
	11		L1	10
			2
T12			3	11
			4
			5
L1			S1	12
2			5	1
			1
3			2
			3

4

4

L5

	5
S1	1

2 2

33

4

4

5

5

II-1

II-2

II-3

II-4

II-5

I-1 cervical roots C1–C8

I-2 thoracic roots T1–T12

III-1

I-3 lumbar roots L1–L5

I-4 sacral roots S1–S5

I-5 coccygeal root

II-1 spinous processes C1–C7

II-2 spinous processes T1–T12

II-3 spinous processes L1–L5

II-4 spinous processes S1–S5

II-5 coccyx

III-2

III-1 spinal cord segments C1–C8

III-2 spinal cord segments T1–T12

III-3 spinal cord segments L1–L5

III-4 spinal cord segments S1–S5

III-5 spinal cord segment Co1

III-3

III-4

III-5

Fig. 7.1 Topographical relations of the vertebral column and nerve roots to the spinal cord. The growth of the spinal cord during embryonic development lags behind that of the spinal column; therefore, more caudally lying nerve roots traverse greater distances in the spinal subarachnoid space to reach their exit foramina. In the conventional numbering system, the cervical spinal nerves exit the spinal canal above the correspondingly numbered vertebra, while all spinal nerves from T1 downward exit below the correspondingly numbered vertebra.

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Diseases of the Spinal Cord

142 7 Diseases of the Spinal Cord

			Fig. 7.2 Important fiber tracts of the
	fasciculus
			spinal cord (cross-sectional view). De-
	gracilis
		posterior columns	scending tracts are shown in red, as-
	fasciculus
			cending tracts in gray.
	cuneatus

posterior spinocerebellar tract lateral corticospinal tract

reticulospinal tract

lateral spinothalamic tract anterior spinocerebellar tract anterior spinothalamic tract

		vestibulospinal tract
	anterior spinal a.	anterior corticospinal
		tract

interneurons, i. e., relay neurons for the conducting pathways and reflex loops;

motor neurons in the anterior horns, whose efferent axons travel in the peripheral nerves;

somatosensory neurons in the dorsal horns (although many sensory neurons are located outside the spinal cord, in the spinal ganglia);

nociceptive sensory neurons in the dorsal horns that receive and transmit impulses mainly from pain and temperature fibers; and

autonomic neurons in the lateral horns.

The topographic relations of the spinal cord, vertebral column, and nerve roots are shown in Fig. 7.1, and the major ascending and descending pathways of the spinal cord are shown in Fig. 7.2. The blood supply of the spinal cord is described below (p. 148).

The Main Spinal Cord Syndromes and Their Anatomical Localization

Diseases of the spinal cord, like those of the brain, can be of traumatic, vascular, neoplastic, paraneoplastic, infectious,inflammatory, metabolic, endocrine, toxic, or hereditary degenerative origin. The clinical manifestations of spinal cord lesions depend on their level and extent and are largely independent of etiology. Thus, the first step in the diagnostic evaluation of spinal cord diseases, as of brain diseases, is topographical localization, i. e., the deduction of the level of the lesion from the patient’s constellation of neurological deficits. The next step is the determination of the etiology, usually based on further criteria (accompanying nonneurological manifestations, temporal course, results of ancillary tests).

Spinal cord transection syndrome is the pattern of neurological deficits resulting from damage of the entire cross-section of the spinal cord at some level. Most acutely arising cases of the complete spinal cord transection syndrome are of either traumatic or ischemic origin; rare cases are due to inflammation or infection (transverse myelitis) or nontraumatic compression (e. g., by a hematoma or tumor). The clinical features of the spinal cord transection syndrome are:

dysfunction of all of the ascending sensory pathways up to the level of the lesion, and of the posterior horns and posterior roots at the level of the lesion: there is a sensory level below which all modalities of sensation are impaired or, in a complete transection, absent;

bilateral pyramidal tract dysfunction: spastic paraparesis or paraplegia, or, with cervical lesions, spastic quadriparesis or quadriplegia (immediately after a trauma, in the phase of “spinal shock” and diaschisis, there is usually flaccid weakness, which subsequently becomes spastic);

bladder dysfunction;

dysfunction of the motor neurons of the anterior horn at the level of the lesion: possibly, flaccid paresis in the myotome(s) supplied by the cord at the level of the lesion, corresponding loss of reflexes, and, later muscle atrophy.

Spinal cord hemisection syndrome (Brown−Séquard syndrome, e. g., caused by a compressing tumor). An anatomical or functional disconnection of one half of the spinal cord exactly to the midline is a rare event. The associated symptoms and signs are described in Table 7.1. Incomplete unilateral lesions are, understandably, more common and present with a subset of these manifestations.

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The Main Spinal Cord Syndromes and Their Anatomical Localization 143

Table 7.1 Brown−Séquard syndrome

Involved structure	Ipsilateral deficits	Contralateral deficits
Pyramidal tract	paresis
Lateral spinothalamic tract		diminution or loss of pain and temperature
		sensation (dissociated sensory deficit)
Anterior spinothalamic tract		mildly diminished sense of touch
Vasomotor fibers of the lateral columns	initially, warmth and redness of the skin;
	sometimes absence of sweating

“Overload” of the contralateral spinothalamic tract with tactile stimuli?

Posterior columns

Anterior horns and anterior roots

transient cutaneous hyperesthesia

loss of proprioception and vibration sense

segmental muscular atrophy and flaccid weakness

Entering posterior roots	segmental anesthesia and analgesia

Central cord syndrome is the classic presentation of syringomyelia (see below), but can also be due to an intramedullary hemorrhage or tumor. Its clinical features are:

pyramidal tract dysfunction: spasticity of the limbs below the level of the lesion; cervical lesions tend to affect the upper limbs more than the lower limbs;

interruption of the pain and temperature fibers of the anterior spinal commissure: bilateral impairment of pain and temperature sensation in the dermatome(s) at the level(s) of the lesion, with preservation of touch (segmentally restricted dissociated sensory deficit); in analogous fashion, concomitant involvement of the posterior horn(s), if present, causes segmental impairment of touch sensation, either unior bilaterally, depending on whether one posterior horn is affected, or both;

dysfunction of the lateral horn/intermediolateral tract: autonomic and trophic disturbances (disturbances of sweating, nail growth, and bone metabolism; hyperkeratosis and edema; all disturbances more pronounced in the upper limbs);

possible concomitant involvement of the spinothalamic tracts: bilateral deficit of pain and temperature sensation below the level of the lesion, with impaired touch sensation;

possible concomitant involvement of the motor neurons of the anterior horns at the level of the lesion: segmentally distributed flaccid weakness, loss of reflexes, and muscle atrophy;

sparing of the posterior horns and spinocerebellar tracts: touch, vibration sense, and proprioception usually remain intact;

bladder dysfunction.

Bilateral lesion of the anterolateral region of the spinal cord (e. g., ischemia in the territory of the anterior spinal a.) produces the following symptoms and signs:

pyramidal tract dysfunction: depending on the level of the lesion, quadriparesis (quadriplegia) or paraparesis (paraplegia), with enhanced intrinsic muscle reflexes and pyramidal tract signs;

involvement of the spinothalamic tracts and the pain and temperature fibers crossing in the anterior spinal commissure: dissociated sensory deficit in the entire region of the body below the level of the lesion; less commonly, the spinothalamic tracts are spared and there is a segmentally restricted dissociated sensory deficit;

intact posterior columns: no impairment of touch or proprioception;

bladder dysfunction.

Isolated or combined long tract processes (of various causes) present with:

for example, pure spastic paraparesis (isolated lesion of the pyramidal tracts, e. g., in spastic spinal paralysis);

impaired touch and position sense (posterior column lesion);

ataxia (lesion of the spinocerebellar tracts and/or posterior columns);

combinations of the above (e. g., pyramidal tract and posterior column dysfunction in funicular myelosis, dysfunction of both of these and the spinocerebellar tracts in Friedreich ataxia).

Anterior horn lesions (e. g., spinal muscle atrophy, acute poliomyelitis) cause the following manifestations:

flaccid weakness of various muscles, muscle atrophy (and fasciculations in chronic processes),

diminution or loss or reflexes,

no sensory impairment.

Combined anterior horn and long tract lesions , e. g., in amyotrophic lateral sclerosis (simultaneous involvement of the anterior horn ganglion cells and of the pyramidal and corticobulbar tracts due to upper motor neuron degeneration; brisk reflexes).

Conus medullaris syndrome (Fig. 7.3). The conus medullaris is the lower end of the spinal cord and lies in the spinal canal at the L1 level. An isolated conus lesion typically produces:

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144 7 Diseases of the Spinal Cord

a		C1			Lesion at the C7 level
					musculocutaneous n.
		C7
		C8
		T1	C7		radial n.
			T1
					( )
					(—)
	T12				(—)
S1			T12
			L1
					( )
				L5
			S1
					( )
				Coc	(	)
b		C1			Lesion at the T10 level
		C7
		C8	C7
		T1
			T1
	10				( )	( )
	T12	10			(—)	(—)
	L1
S1			T12
			L1

( )

L5

S1

( )

( )

Coc

Fig. 7.3a, b Neurological deficits resulting from spinal cord transection at the C7 level (a) and at the T10 level (b).

Fig. 7.3c,d

loss of all modalities of sensation

() normal reflex

(—) absent reflex

( ) exaggerated reflex

spastic bladder paralysis

flaccid bladder paralysis

bladder dysfunction,

dysfunctional defecation with sphincter weakness,

impairment of sexual function,

possibly a dissociated sensory deficit or complete loss of sensation in the cutaneous distribution of the sacral and coccygeal spinal cord segments (saddle anesthesia);

usually, preserved motor function and absence of pyramidal tract signs.

Cauda equina syndrome (Fig. 7.3) results from compression of the nerve roots coursing through the spinal

canal below the conus medullaris, i. e., below the L1/2 level. Unlike conus medullaris syndrome, it involves a variably severe impairment of sensory and motor function in the lower limbs. Its clinical manifestations are:

flaccid weakness and areflexia of the lower limbs, without pyramidal tract signs;

impairment of all sensory modalities in multiple lumbar and/or sacral dermatomes, usually most pronounced in the “saddle” area;

impaired urination, defecation, and sexual function, with sphincter weakness.

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