Atlas of the Human Brain and Spinal Cord, 2nd Edition

Section 3 - Neuroanatomical Lesions

 

 

Overview

The following anatomical lesions are correlative teaching exercises and for the most part are not seen as pure entities in the practice of clinical neurology. They represent only a modest sample of possible structure-deficit constructions. The ultimate goal of studying these cases is to aid the student in acquiring the prerequisite functional neuroanatomical background to diagnose accurately the level and extent of neuropathology within the human neuraxis.

It is suggested that the student examine the plate in question and locate the structures involved in the syndrome. He or she should then call to mind the motor or sensory modalities mediated by these structures. With this information at hand, the student should be able to list the expected neurological deficits.

The following procedure for study proves to be quite useful:

1. Outline the appropriate transverse section on tracing paper.

2. Trace in the structures affected.

3. Label the structures.

4. List the motor or sensory modalities of the structures.

5. List the neurological deficits expected to result from destruction of the structures.

It is hoped that the resourceful student will not limit study to those plates given as examples.

 

SYNDROME Spinal Cord Hemisection (Brown-Séquard Syndrome)

Plate 18 Spinal Cord at Midcervical Level

Structures Affected

1. Gracile fasciculus

2. Cuneate fasciculus

3. Dorsal spinocerebellar tract

4. Ventral spinocerebellar tract

5. Lateral corticospinal tract

6. Ventral corticospinal tract

7. Lateral spinothalamic tract

8. Ventral spinothalamic tract

9. Dorsal horn

10. Ventral horn

11. Lateral tectotegmentospinal tract (lateral funiculus)

Clinical Manifestations

1. & 2. Ipsilateral loss of finest tactile discrimination, of positional and vibratory sense, and of all proprioceptive sensibility below lesion

3. Ipsilateral incoordination of movement below lesion but difficult to demonstrate because of motor paralysis

4. Contralateral incoordination of movement below lesion (VSCT crossed)

5. Ipsilateral spastic paresis below lesion

6. Contralateral slight motor involvement below lesion

7. Contralateral loss of pain and temperature sensibility below lesion

8. Contralateral loss of crude touch below lesion

9. Ipsilateral loss of pain and temperature at level of lesion

10. Ipsilateral flaccid paralysis at level of lesion

11. Ipsilateral Horner's syndrome (ptosis, miosis, hemianhydrosis, apparent enophthalmos)

SYNDROME Syringomyelia

Plate 18 Spinal Cord at Midcervical Level

Structures Affected

1. Ventral horn

2. Ventral white commissure

Clinical Manifestations

1. Flaccid paralysis

2. Bilateral loss of pain and temperature sensibility

 

SYNDROME Subacute Combined Degeneration (Vitamin B12 Neuropathy)

Plate 18 Spinal Cord at Midcervical Level

Structures Affected

1. Dorsal funiculi

2. DSCTS

3. VSCTS

4. Lateral corticospinal tracts

Clinical Manifestations

1. Loss of proprioception and tactile sensation

2. Loss of motor coordination (ataxia)

3. Loss of motor coordination (ataxia)

4. Spastic paresis

SYNDROME Amyotrophic Lateral Sclerosis (ALS)

Plate 18 Spinal Cord at Midcervical Level

Structures Affected

1. Lateral corticospinal tracts

2. Ventral corticospinal tracts

3. Ventral horns

Clinical Manifestations

1. Spastic paresis

2. Spastic paresis

3. Flaccid paralysis

 

SYNDROME Dorsal Column Disease (Tabes Dorsalis)

Plate 18 Spinal Cord at Midcervical Level

Structures Affected

1. Dorsal funiculi

2. Dorsal roots

Clinical Manifestations

1. Loss of proprioception and tactile sensation (sensory ataxia)

2. Paresthesias, pain, and hyporeflexia

SYNDROME Poliomyelitis

Plate 18 Spinal Cord at Midcervical Level

Structures Affected

1. Ventral horns

Clinical Manifestations

1. Flaccid paralysis

SYNDROME Werdnig-Hoffmann Disease

Plate 18 Spinal Cord at Midcervical Level

Structures Affected

1. Ventral horns

Clinical Manifestations

1. Flaccid paralysis

 

SYNDROME Friedreich's Hereditary Ataxia (Spinocerebellar Ataxia)

Plate 18 Spinal Cord at Midcervical Level

Structures Affected

1. Gracile fasciculi

2. Cuneate fasciculi

3. Dorsal spinocerebellar tracts

4. Ventral spinocerebellar tracts

5. Lateral corticospinal tracts

6. Dorsal root fibers

7. Cerebellar cortex

8. Dentate nuclei

9. Cerebellar peduncles

Clinical Manifestations

1. & 2. Ipsilateral loss of finest tactile discrimination, of positional and vibratory sense, and of all proprioceptive sensibility below lesion

3. Ipsilateral incoordination (ataxia) of movement below lesion

4. Contralateral incoordination (ataxia) of movement below lesion (VSCT crossed)

5. Ipsilateral spastic* paresis below lesion

6. Ipsilateral hypo- or areflexia

7., 8. & 9. Cerebellar dyssynergia including: dysdiadochokinesia, dysmetria, dysarthria (slow, staccato, and explosive speech), wide-based reeling cerebellar gait (ataxia), horizontal nystagmus, and intention tremor.

 

SYNDROME Ventral Spinal Artery Thrombosis at Cord Level

Plate 18 Spinal Cord at Midcervical Level

Structures Affected

1. Ventral horns

2. Lateral horns

3. Lateral corticospinal tracts

4. Spinothalamic tracts

5. Spinocerebellar tracts

Clinical Manifestations

1. Complete flaccid paralysis of all innervated muscles

2. Vasodilation and lack of sweating in corresponding dermatomes; Involvement of Th1 (ciliospinal center of Budge) results in Horner's syndrome:

a.   Miosis

b.   Ptosis

c.   Hemianhydrosis with hemivasodilation of face

d.   Apparent enophthalmos

3. Following the initial spinal shock phase (flaccid paralysis and areflexia); spastic paraplegia with hyperactive deep tendon reflexes and ankle clonus. Plantar reflexes extensor.

4. Loss of pain and temperature below lesion

5. Cerebellar incoordination would be expected but is masked by paralysis. Urinary retention with “overflow” incontinence results from interruption of descending autonomic pathways

SYNDROME Medial Medullary Syndrome

Plate 24 Medulla Oblongata at Midolivary Level

Structures Affected

1. Hypoglossal nerve roots

2. Corticospinal tracts

3. Medial lemniscus

Clinical Manifestations

1. Ipsilateral flaccid paralysis of tongue

2. Contralateral hemiparesis of trunk and extremities

3. Contralateral loss of proprioception, discriminative tactile sensation and vibration sense from trunk and extremities

 

SYNDROME Lateral Medullary Syndrome (PICA Syndrome or Wallenberg's Syndrome)

Plate 24 Medulla Oblongata at Midolivary Level

Structures Affected

1. Vestibular nuclei (medial and inferior)

2. Inferior cerebellar peduncle

3. Nucleus ambiguus and/or root fibers

4. Glossopharyngeal root fibers

5. Spinal lemniscus

6. Spinal trigeminal nucleus and/or tract

7. Lateral tectotegmentospinal tract (not shown)

8. Medial reticular formation (inspiratory center)

Clinical Manifestations

1. Nystagmus, nausea, vomiting, and vertigo

2. Ipsilateral cerebellar signs (ataxia, dysmetria, dysdiadochokinesia)

3. Ipsilateral flaccid laryngeal and pharyngeal paralysis (loss of gag reflex, dysarthria, dysphagia)

4. Loss of gag reflex (afferent limb)

5. Contralateral loss of pain and temperature from trunk and extremities

6. Ipsilateral loss of pain and temperature from face

7. Ipsilateral Horner's syndrome (ptosis, miosis, hemianhydrosis, apparent enophthalmos)

8. Singultus

SYNDROME Inferior Lateral Pontine Syndrome (AICA Syndrome)

Plate 29 Pons at the Level of the Trapezoid Body and the Facial Colliculus

Structures Affected

1. Intra-axial fibers of facial nerve and/or facial nucleus

2. Spinal trigeminal nucleus and/or tract

3. Intra-axial root fibers of vestibulocochlear nerve and/or vestibular nuclei

4. Spinal lemniscus

5. Lateral tectotegmentospinal tract

6. Inferior cerebellar peduncle and middle cerebellar peduncle

Clinical Manifestations

1. Ipsilateral flaccid facial paralysis; loss of taste from anterior two thirds of tongue

2. Ipsilateral loss of pain and temperature from face

3. Ipsilateral tinnitus and/or peripheral deafness, nystagmus, nausea, vomiting, and vertigo

4. Contralateral loss of pain and temperature from trunk and extremities

5. Horner's syndrome (ptosis, miosis, hemianhydrosis, and apparent enophthalmos)

6. Ipsilateral cerebellar signs (ataxia, dysmetria, dysdiadochokinesia)

 

SYNDROME Medial Pontine Syndrome (Basilar Artery, Median Penetrating Branches)

Plate 29 Pons at the Level of the Trapezoid Body and the Facial Colliculus

Structures Affected

1. Root fibers of abducent nerve

2. Corticospinal tracts

3. Corticobulbar tracts

4. Medial lemniscus

Clinical Manifestations

1. Ipsilateral flaccid lateral rectus paralysis

2. Contralateral hemiplegia of trunk and extremities

3. Facial weakness

4. Contralateral loss of proprioception and discriminative tactile sensation from trunk and extremities

SYNDROME Internuclear Ophthalmoplegia (MLF Syndrome)

Plate 29 Pons at the Level of the Trapezoid Body and the Facial Colliculus

Structures Affected

1. Medial longitudinal fasciculus (MLF)

Clinical Manifestations

1. Ipsilateral medial rectus paralysis on attempted horizontal gaze; monocular nystagmus of the abducting eye. Convergence is preserved.

SYNDROME Dorsal Midbrain Syndrome (Parinaud's Syndrome)

Plate 36 Mesencephalon at the Level of the Superior Colliculus

Structures Affected

1. Superior colliculus

Clinical Manifestations

1. Paralysis of upward gaze, to a lesser extent, downward gaze. Practically always pupillary disturbances and, frequently, absence of convergence. Pupils characteristically do not react to light but do react to near focusing and differ from Argyll Robertson pupil only insofar as they are not miotic. Absence of convergence common when downward gaze is affected, but convergence is often retained when only upward gaze is involved.

 

SYNDROME Paramedian Midbrain Syndrome (Benedikt's Syndrome)

Plate 36 Mesencephalon at the Level of the Superior Colliculus

Structures Affected

1. Root fibers of oculomotor nerve

2. Red nucleus

Clinical Manifestations

1. Ipsilateral flaccid paralysis of medial rectus, inferior oblique, superior rectus, inferior rectus, levator palpebrae, and intrinsic musculature of the bulb (complete internal ophthalmoplegia)

2. Contralateral dyskinesia (hyperkinesia, ataxia), and intention tremor of arm only

SYNDROME Medial Midbrain Syndrome (Weber's Syndrome)

Plate 36 Mesencephalon at the Level of the Superior Colliculus

Structures Affected

1. Root fibers of oculomotor nerve

2. Corticospinal tract

3. Corticobulbar tract

4. Frontopontine tract

Clinical Manifestations

1. Ipsilateral flaccid paralysis of medial rectus, inferior oblique; superior rectus, inferior rectus, levator palpebrae, and intrinsic musculature of the bulb (complete internal ophthalmoplegia)

2. Contralateral hemiplegia

3. Contralateral weakness of lower face (VII), tongue (XII), and palate (X)

4. No outstanding clinical signs

 

SYNDROME Argyll Robertson Pupil

Plate 50 Frontal Section Through the Posterior Thalamus at the Level of the Posterior Commissure and the Medial and Lateral Geniculate Bodies

Structures Affected

1. Pretectal area

Clinical Manifestations

1. Typical Argyll Robertson pupil is miotic in both eyes (not necessarily to same degree in both eyes; pupils frequently irregular). Absence or sluggishness of miotic reaction to light, both direct and consensual. Preservation of miotic reaction to near stimulus. Inverse pupillary reaction is occasionally present (slight dilation of pupil when light is shone in the eye).

Note: The Argyll Robertson pupil must be differentiated from the benign Adie's pupil. The Adie's or myotonic pupil consists of absent or retarded constriction of the pupil with light or near stimulus. The Adie's pupil will dilate slowly when patient is put in a dark room and will then contract slowly in response to light. These patients are usually without accompanying neurological disease. This condition is usually unilateral, occurring generally in young women, with absent knee and ankle jerks.

SYNDROME Hemiballism

Plate 48 Frontal Section through the Midthalamus at the Level of the Subthalamic Nucleus and the Mamillary Bodies

Structures Affected

1. Subthalamic nucleus

Clinical Manifestations

1. Purposeless, involuntary, violent, and forceful flinging movement of proximal musculature of the upper and lower extremities

SYNDROME Huntington's Chorea

Plate 40 Frontal Section through the Neostriatum at the Level of the Rostrum of the Corpus Callosum

1. Caudate nucleus and putamen

2. Frontal cortex

1. Choreoathetoid hyperkinesia

2. Dementia

SYNDROME Parkinsonism (Hypokinetic-Rigid Syndrome)

Plate 36 Mesencephalon at the Level of the Superior Colliculus

Structures Affected

1. Substantia nigra, caudate nucleus, and putamen

Clinical Manifestations

1. Rigidity in both extensor and flexor muscles (“leadpipe” and “cogwheel” rigidity), masked facies and drooling, resting (static) “pill-rolling” tremor. Bradykinesia (slowness and marked paucity of movement with diminished adventitial movements like arm swinging). Typical stooped posture and shuffling gait. Festination.

 

SYNDROME Hepatolenticular Degeneration (Wilson's Disease)

Structures Affected

1. Putamen

2. Caudate nucleus

3. Globus pallidus

4. Subthalamic nucleus

5. Red nucleus

6. Substantia nigra

7. Dentate nucleus

8. Superior cerebellar peduncle

9. Focal degeneration of frontal cortex

10. Liver (cirrhotic)

11. Kayser-Fleischer ring at sclerocorneal junction

Note: In this particular disease, there is such an intermix of extrapyramidal, cerebellar, cortical, and metabolic involvement that no attempt is made to correlate specific structures to specific or nonspecific neurological deficits.

Clinical Manifestations

Initial symptoms:

· Tremor of a limb or head

· Bradykinesia (slowness of movement)

· Dysarthria, dysphagia, hoarseness

· Occasional choretic movement of limbs

· Impairment of intellect, excessive emotionality

The “classic” syndrome:

· Generalized rigidity

· Bradykinesia

· Dysarthria, dysphagia, hoarseness, and drooling

· Masked facies with mouth constantly agape

· Static tremor which increases when arms are outstretched (“flapping” tremor at wrists; “wingbeating” tremor at shoulders); cerebellar intention tremor

· Festinating gait with forward stoop

· Absence of arm swinging

· Progressive dementia, emotional lability, seizures, progressive muscular weakness. In variant forms of this disease, the following may appear:

· Choreoathetosis, prominent dystonic postures, cerebellar ataxia with minimal rigidity

· Deep tendon reflexes, often hyperactive

· Plantar reflexes, often extensor

SYNDROME “Classic” Stroke of Internal Capsule

Plate 56 Horizontal Section through the Rostrum and the Splenium of the Corpus Callosum

Structures Affected

Internal capsule

1. Corticobulbar fibers (genu)

2. Corticospinal tract (posterior limb)

3. Sensory radiations to somesthetic cortex (posterior limb)

4. Visual radiations to striate cortex (sublenticular part of posterior limb)

5. Auditory radiations to auditory cortex (sublenticular part of posterior limb)

6. Visual radiations to striate cortex (postlenticular part of posterior limb)

Clinical Manifestations

These manifestations are seen after the resolution of the initial flaccid shock phase of capsular stroke.

Symptoms are contralateral

1. Lower facial weakness (VII), weakness of tongue (XII), palatal weakness (X)

2. Spastic hemiparesis, hyperactive deep tendon reflexes, clonus (wrist, patellar, ankle), plantar reflex extensor (Babinski), flexor reflex of fingers (Hoffmann's sign), suppression or abolition of superficial reflexes (abdominal and cremasteric), symmetrical synkinesias (mirror movements), characteristic hemiplegic posture (upper limb in flexor-contracture, lower limb in extensor-contracture), and hemiplegic gait (circumduction of affected leg)

3. In varying degree following numbness and paresthesias: hemihypesthesias (loss of pain and temperature, loss of epicritic tactile sensibility, loss of vibration sense, loss of position sense [kinesthesia])

4. Hemianopia

5. Hemihypacusis

6. Hemianopia

Note: A multitude of additional fiber trajectories (extrapyramidal) is affected in this lesion which certainly influences the total motor deficit (abnormal reflexes, modified posture, and the poorly understood neurological phenomena of spasticity and muscle dystonia).

 

SYNDROME Visual Field Deficits

Plate 60 Horizontal Section through the Superior Colliculus, the Medial and the Lateral Geniculate Bodies, the Hypothalamus, and the Amygdaloid Nucleus

Structures Affected

1. Optic fasciculus (nerve) (complete transection)

2. Optic chiasm

a.   Midsagittal section

b.   Bilateral constriction

3. Optic tract (complete transection)

4. Lateral geniculate body

5. Geniculocalcarine tract (complete transection)

6. Meyer's loop transection

7. Visual cortex of

a.   Cuneus

b.   Lingual gyrus

Clinical Manifestations

1. Complete ipsilateral blindness; absent direct light response

2.

a.   Bitemporal hemianopia

b.   Binasal hemianopia

3. Contralateral homonymous hemianopia

4. Contralateral homonymous hemianopia

5. Contralateral homonymous hemianopia

6. Contralateral upper homonymous quadrantanopia

7.

a.   Contralateral lower homonymous quadrantanopia

b.   Contralateral upper homonymous quadrantanopia

Visual Field Deficits

Note: 1) Contralateral in this case means that if the lesion, for example, is on the left side, the homonymous field deficit will be on the right side in both visual fields. 2) Destruction of visual (striate) cortex results in cortical blindness. 3) Destruction of the cuneus bilaterally (gunshot wound) results in a field deficit called lower altitudinal hemianopia. 4) Destruction of the lingual gyrus bilaterally (gunshot wound) results in a field deficit called upper altitudinal hemianopia. 5) Inferior nasal fibers (primarily central fibers) follow a peculiar course in the anterior chiasm and loop up into the contralateral optic fasciculus. If the optic fasciculus is transected close to the chiasm, these fibers may be involved. Such involvement results in a junctional scotoma.