CLINICAL EVALUATION IN NEUROLOGICAL DISEASE

Primary aim of clinical evaluation in a suspected neuro­logical disease is to: (a) localize the site of lesion (topo­graphic diagnosis) and (b) identify the probable cause of lesion (etiological diagnosis), based on detailed history, general examination and neurological examination.

History: Possibility of a neurological disease should be considered in presence of one or more of following complaints: (a) altered sensorium or behavioral changes,

(b) seizure or movement disorders, (c) motor deficits,

(d) abnormal vision, hearing or speech, (e) sensory or autonomic disturbances, (f) developmental delay/ regression or mental retardation.

Each of these complaints should be assessed for— onset (sudden/insidious), progression (static, progressive or improving) and duration (short, long, since birth). Other important histories in neurological disease include: (a) family history of neurological or behavioral illness, (b) perinatal history of complications, (c) history of head/ spinal trauma, (d) thorough developmental history.

General examination should be specifically directed towards: (a) anthropometry, e.g. head circumference for microcephaly/hydrocephalus; (b) vital signs, e.g. BP, HR, RR, which are frequently abnormal in presence of raised intracranial pressure or autonomic disorders;

(c) cutaneous stigmata for neurocutaneous disorders;

(d) dysmorphic features in congenital anomalies; (e) extracranial septic/tubercular foci; and (f) spinal tenderness/ deformities.

Neurological examination of a child requires consi­derable patience and flexibility; and includes five major areas of assessment: (a) higher functions, (b) signs of meningeal irritation, (c) cranial nerves, (c) motor system,

(d) sensory system, (e) localizing signs including soft neurological signs.

A. Assessment of higher functions, unlike adults, is usually based on simple observations rather than specific tests, with useful inputs from parents and includes assessment of: (a) general behavior, e.g.

Sensorium should be recorded in terms of Modified Glasgow coma scale, if possible, which also helps to monitor changes over time (see Table 18.7).

However, it is often difficult to assess a young child in isolated fields of higher functions and all cases should at least be categorized as: (a) conscious, (b) comatose, or (c) delirious (Ch 18.3). Vegetative state is a term commonly used to refer the patients quot;in a wakeful state and not unconscious, but are not aware of the surroundingsquot;.

B. Signs of meningeal irritation are produced due to inflammation of spinal meninges, leading to irritation of nerve roots and protective spasm of spinal muscles on stretching of spinal cord. Important signs of meningeal irritation include:

• Nuchal rigidity, i.e. pain and stiffness of neck, during its flexion.

• Kernig sign, i.e. pain on extension of the leg, following hip flexion.

• Brudzinski sign, i.e. involuntary flexion of knee and hips, on passive flexion of the neck.

C. Examination of cranial nerves: While formal cranial nerve examination is possible only in older children, all except olfactory nerve may be assessed even in infants or comatose children with age-appropriate methods, as follows:

• Olfactory nerve evaluation is often difficult, unreliable and unnecessary. Anosmia in children is usually transient, due to local rhinitis.

• Optic nerve in infants and toddlers is best assessed by fundus examination, though older cooperative children may be assessed for—(a) visual acuity, (b) field of vision and (c) color vision.

In young/comatose children, menace reflex (reflex blinking to a sudden menacing ot threatening gesture towards patient's eye) or light reflex may be used as an indicator of optic nerve function, other causes, e.g. opaque media (cataract) are excluded.

Field of vision may be informally tested by observing the movements of eyes, following a colourful moving object.

• Extra-ocular nerves (occulomotor, trochlear and abducens) are tested by range of extraocular movements in different directions, which may require Doll's eye maneuver in young/comatose children.

Doll's eye maneuver involves observation of eye movements after sudden turning of head on one side, which leads to conjugate deviation of eyes on other side. Absence of this oculocephalic response indicates external ophthalmoplegia on opposite side of head movement. Maneuver needs to be repeated on other side as well as after flexion and extension of neck.

Occulomotor palsy is also characterised by—(a) ptosis and (b) loss of accommodation.

Lateral gaze palsy due to abducens involvement, is usually a false localizing sign in raised intracranial pressure due to longest intracranial course of nerve.

Presence of vertical, rotatory or horizontal nystag­mus indicates vestibular, cerebellar or brain stem disease, while skew deviation of eyes indicates cerebellar or pontine lesion.

• Trigeminal nerve is a mixed nerve with three divi- sions-ophthalmic, maxillary and mandibular. Sensory functions are tested by corneal reflex and facial sensa­tions, while motor functions are assessed by mastica­tion activity and jaw jerk.

• Facial nerve innervates muscles of facial expression (motor) and anterior 2/ 3^rd of tongue (taste). Important signs of facial palsy include—(i) asymmetric facial expressions, (ii) lesser nasolabial fold on affected side on cry, smile, teeth-clenching etc., (iii) asymmetric palpebral fissure with inability to close the eye on affected side, (iv) drooling of saliva and feeds from weaker side.

Absence of creases on forehead while child is frowning or looking upwards, indicates infranuclear facial palsy (d/d supranuclear palsy), as upper face receives cortical innervation from both sides.

• Vestibulo-cochlear nerve involvement should be suspected in cases with deafness, tinnitus or vertigo. Vestibular component is difficult to assess in young children, unless vertigo is complained.

Auditory component may be tested by standard Rinni's or Weber's test in older children, while young children may be assessed by response to familiar sounds or startle response. Audiometry is a part of routine assessment in high-risk children.

• Glossopharyngeal, vagus and accessory nerve lesions often co-exist due to proximity of their nuclei in brain­stem and common cranial outlet via jugular foramen. Supranuclear or pseudobulbar palsy of these nerves is less common than infranuclear bulbar palsy.

Important signs of bulbar or pseudobulbar palsy include—(a) absence of gag reflex, (b) asymmetry of soft palate with uvular deviation, (c) hoarseness of voice or nasal twang, (d) difficulty in swallowing, and

(e) nasal regurgitation of feeds. Winging of scapula and inability to shrug the shoulders indicates XI nerve paralysis.

• Hypoglossal nerve is a purely motor nerve of the tongue and assessed by observing shape, asymmetry (unilateral lesion), and fasciculations of tongue. Inability to protrude the tongue indicates bilateral XII nerve palsy.

D. Examination of motor system should be preceded by assessment of musculoskeletal system, especially for painful inflammatory disorders, to avoid misinterpretation of neurological findings. Important steps in motor evaluation include examination of—(a) gait, (b) posture, (c) muscle bulk, (d) tone, (e) power, (f) reflexes, and (g) coordination.

a. Gait: Abnormal but painless gait is an indicator of neuromuscular disease (Table 18.1), which should be differentiated by developmental or painful gait of orthopedic disorders (Ch 23.3).

b. Posture: Common postural abnormalities in CNS disorders are as follows:

± Decorticate posture (bilateral flexion of upper limbs and extension of lower limbs) in pyramidal tract lesion above/at the level of internal capsule.

TABLE 18.1: Common gait abnormalities

• Spastic or hemiplegic (Cicumduction of legs)#8726;

In pyramidal tract lesion

• Scissoring (Crossed leg walking)

In cerebral palsy

• High-stepping (Excess lifting of affected foot)

In peripheral neuropathies or contractures

• Stamping (High-stepping gt; forceful grounding)

In post.

• Ataxic (Staggering with side-swaying)

In cerebellar or extrapyramidal lesion

• Shuffling (Forward swaying, with rapid steps)

In extrapyramidal lesions (rare in children)

• Waddling gait (Side to side swaying of hips)

In hip-girdle weakness, e.g. DDH, DMD

• Antalgic gait (Painful)

In inflammatory or orthopedic leg problems

DDH: Developmental dislocation of hip; DMD: Duchhene muscular dystrophy.

- Decerebrate posture (extension of all limbs, with spasticity) in mixed pyramidal and extrapyramidal lesions, usually at brainstem level (see Fig. 18.11)

- Frog-like posture (extension of all four limbs with hypotonia) in generalized neuromuscular disorder (floppy child), though painful conditions, e.g. scurvy, should be excluded.

- Asymmetric posture indicates focal motor lesions, nerve injuries (foot/hand-drop) or contractures.

- Ill-sustained posture indicate sensory or cerebellar ataxia. A positive Romberg sign, i.e. inability to maintain steady posture on standing with open eyes, indicates cerebellar ataxia. In sensory ataxia, Romberg sign is positive with closed eyes but negative with open eyes.

c. Bulk of different muscles is assessed by observation and comparing from other side. In doubtful cases, recording of limb circumference on both sides is required to detect unilateral wasting (neuropathies) or pseudohypertrophy (myopathies). Muscle bulk is normal upper motor neuron lesions, except in later stages due to disuse atrophy.

d. Muscle tone must be assessed for passive tone by-(a) abnormal posture, (b) soft/flabby or stiff feel, or active tone by (c) shaking the unsupported limb for range and frailty of movements, and (d) degree of resistance on passive joint movement. It should always be compared from other side.

Common tone abnormalities include: (a) clasp-knife spasticity (initial resistance to movement) in pyramidal tract lesions, (b) cog-wheel rigidity (jerky, intermittent resistance) or lead-pipe rigidity (uniform resistance) in extrapyramidal lesions, (c) hypotonia in cerebellar or neuromuscular disorders.

Vertical suspension of a young infant, holding from axilla, is a useful method to assess the tone. Scissoring of lower limbs or arching of back in this position indicates hypertonia (cerebral palsy), while hypotonic floppy child tends to slip from axillary grip.

e. Muscle power must be assessed and graded (Table 18.2) in different group of muscles at different joints, by passive observation of spontaneous movements and active testing of strength against gravity/ resistance. Examination of power also includes testing for Gower sign (Ch 18.16.4) and muscles of respiration (paradoxical respiration).

f. Reflexes: Examination of reflexes includes assessment of superficial, deep and neonatal reflexes (in newborns and suspected cerebral palsy) as well planter response. Asymmetry of reflexes has important localizing value.

- Important superficial reflexes include conjunctival or corneal reflex (V/VII cranial nerve), abdominal reflex (T_g12), cremasteric reflex (L₁), and anal reflex (S₃_4). Superficial reflexes are lost in lower motor neuron lesions.

- Important deep tendon reflexes with their root palsy include jaw jerk (pontine reflex), biceps (C₅), triceps (C₆,₇), supinator (C₆), knee (L₃_4), and ankle (L₅-S₁). Deep tendon reflexes must be graded according to the strength of response (Table 18.3). Presence of patellar and ankle clonus is an unequivocal sign of pyramidal tract lesions.

Abnormal deep tendon reflexes include: (a) hyperreflexia in upper motor neuron lesions, (b) hypo-/a-reflexia in lower motor neuron lesions and (c) pendular jerks in cerebellar disorders.

g. Plantar response is assessed by standard method (stroking on lateral border of sole), though other techniques may be useful in cases with equivocal response, e.g. Oppenheim's maneuver (pressure on tibial shin), Gordon's method (squeezing of tendo Achillis) or Chaddock's sign (scratching on lateral malleolus).

Extensor planter response (positive Babinski sign) has two components—(i) extension of great toe and (ii) fanning of other toes, and indicates upper motor neuron lesion. However it may be physiological in infancy due to incomplete myelination or during sleep. Fanning of the toes is usually absent in physiological extensor planter response.

h. Neonatal reflexes and their significance is discussed in Chapter 12.5. While asymmetric neonatal reflexes,

e. g. Moro's reflex indicate local pathology, persistence of neonatal reflexes beyond normal timing of their disappearance is seen in cerebral palsy.

i. Coordination is tested by finger-to-nose test in upper limbs and heel-to-shin test or tandem walking in lower limbs. Abnormal coordination signifies cerebellar or sensory dysfunction. Inability to perform these tests

MRC: Medical Research Council

*Knee jerk may be normally brisk. Pathologically brisk knee jerk is often accompanied by crossed adductor response, i.e. contraction of contralateral adductors

even with open eyes indicate cerebellar lesion. Other methods to assess co-ordination include gait, hand­writing, dysdiadochokinesia, etc.

E. Sensory examination is difficult in pre-school children (except for pain), while older and cooperative children, specially those with spinal disorders, should be tested for—(a) pain by pin-prick, (b) light touch by cotton-wool, (c) deep touch by finger-pressure, (d) temperature by hot/ cold water test-tubes, (e) position sense by great toe manipulation, and (f) vibration sense by tuning-fork, to localize the spinal level of disease.

Other cortical senses, e.g. two-point discrimination (using a protector with two legs 1 cm apart), sensory inattention (missing one of the sensations, when two points are stimulated together) and astereognosis (inability to identify an object by touch, without visualization) may be assessed in cooperative children.

F. Abnormal movements, e.g. chorea, athetosis and tremors are easily noticeable on simple observation (Ch

18.9). Specific clinical signs for chorea include milk­maid grip, lizard-tongue, etc. (Ch 17.6). Tremors are best tested on outstretched fingers in a co-operative child. Presence of these movements indicates extra-pyramidal pathology.

G. Urinary bladder dysfunction is an important diagnostic clue in spinal disorders. Bladder function is regulated by three neural mechanisms—(a) excitatory parasympathetic flow (S₂_₃), inhibitory sympathetic flow (L₁₂) and voluntary corticospinal flow. Common types of bladder involvement in CNS disease are:

• Reflex or automatic bladder, i.e. urinary retention with intermittent reflex emptying in upper motor neuron lesions above the lumbar region, due to cut-off of voluntary control but preserved reflex arc.

• Persistent urinary incontinence in lumbar or cauda equina lesions due to cut-off of inhibitory sympathetic flow.

• Autonomic bladder, i.e. persistent urinary retention with overflow incontinence in peripheral nerve injury due to loss of excitatory parasympathetic flow.

In addition, upper motor neuron spinal lesions are also associated with constipation, while peripheral nerve injury may lead to fecal incontinence.

Clinical Localization of Lesion

For the sake of broad anatomical localization, neurological findings may divided into:

A. Cerebral cortex (gray-matter) lesions are characterized by: (a) higher function abnormalities, (b) seizures, (c) speech/vision defects and (d) soft neurological signs, etc. Signs of specific cortical lobe involvement are given in Table 18.4.

B. Motor neuron (white-matter) dysfunction are broadly divided into upper (UMN) and lower (LMN)

*In lesions of dominant hemisphere

*Positive Babinski sign

motor neuron lesions (Table 18.5). Motor deficits may range from minor functional defects to well-defined clinical presentations, e.g. Hemiplegia, i.e. unilateral weakness, Paraplegia, i.e. weakness of both lower limbs, Quadriplegia, i.e. weakness of all four limbs, Diplegia, i.e. spastic weakness of all four limbs but more prominent in lower limbs, and Monoplegia, i.e. weakness of only one limb. Hemiplegia is almost always a UMN lesion (Ch 18.7), while paraplegia may be of either UMN or LMN etiology (Ch 18.16). Quadriplegia/diplegia is mainly seen cerebral palsy, except a few cases of high cervical spine lesions. Monoplegia usually indicates peripheral nerve injury or mild cerebral palsy.

C. Cerebellar dysfunction presents with:

• Ataxic gait/posture (Romberg sign)

• Generalized hypotonia

• Hyporeflexia or pendular jerks

• Ocular signs-nystagmus, skew deviation

• Dysarthria

• Impaired coordination, e.g. dysmetria (finger nose test) or Dysdiadochokinesia (alternate pronation/supination)

D.Extrapyramidal dysfunction presents with:

• Abnormal movements, e.g. chorea or athetosis

• Dystonia

• Decerebrate posture

• Speech impairment

• Vacant, expressionless face (rare in children)

• Shuffling gait (rare in children)

Etiological Categorization of Lesions

According to pathological type of lesion, neurological disorders may be: (a) infective or inflammatory, (b) vascular, (c) neoplastic, (d) degenerative, or (e) traumatic, in origin, apart from congenital anomalies.

• Infective or inflammatory lesions are commonest cause of neurological disease in younger children, presenting with fairly acute onset (of a few days) and progress rapidly unless treated. Presence of fever, extracranial septic foci or toxaemia strongly indicates infective pathology.

• Vascular lesions are typically acute catastrophic in onset, developing over few minutes and recovery starts within few days. Fever may be present or absent, depending on the etiology. BP must always be examined in these cases.

• Neoplastic or other space occupying lesions, e.g. tuberculoma, neurocysticercosis or hematomas are slowly progressive, with gradual onset over a few weeks. Raised intracranial pressure or seizures are predominant presentation in infratentorial and supratentorial space occupying lesions, respectively.

• Traumatic lesions present either immediately after head injury with acute signs of cerebral or motor dysfunction and/or raised intracranial pressure or after many weeks as space-occupying lesions due to formation of subdural hematoma.

• Degenerative lesions, rarest of neurological disorders, present with long history of indeterminate onset, often as waxing and waning course. Regression of milestones is usually the first complaint in young children, while older cases may present with behavioral changes, poor school performance, seizures or UMN signs. Family history is common.

• Congenital anomalies usually manifest at birth as obvious structural defects, e.g. microcephaly/ hydrocephalus, meningomyelocele, etc.; or detected in early infancy during evaluation for functional defects, e.g. developmental delay, spasticity/flaccidity, seizures, etc.

18.2