Neuro Lower Limb

Question 1

How might a UMN lesion affect tone in the lower limb

What about tone in case of LMN lesion

Answer 1

Increased (spasticity or rigidity) +/- ankle clonus

Decreased (hypotonia) or normal

Question 2

How do UMN and LMN lesions affect plantar reflexes in the lower limb

Answer 2

UMN: Upgoing/extensor (Babinski positive)

LMN: Normal (downgoing/flexor) or mute (i.e. no movement)

Question 3

What are the key sections of the lower limb neuro exam

Answer 3

Gather the appropriate equipment (Tendon hammer; Neurotip; Cotton wool; Tuning fork (128Hz))
Intro (WIPERQQ)
General Inspection
Gait
Romberg’s test
Tone/ ankle clonus
Power (Hip, knee, ankle, toes)
Reflexes (knee-jerk, ankle-jerk, plantar)
Sensation (dermatomes, light-touch, pin-prick, vibration, proprioception)
Coordination (heel-to-shin test)
Further assessments and investigations

Question 4

What are the clinical signs you should look out for at the beginning of the lower limb neuro exam

Answer 4

Scars: may provide clues regarding previous spinal or lower limb surgery.

Wasting of muscles: suggestive of lower motor neuron lesions or disuse atrophy.

Tremor: there are several subtypes including resting tremor and intention tremor.

Fasciculations: small, local, involuntary muscle contraction and relaxation which may be visible under the skin. Associated with lower motor neuron pathology (e.g. amyotrophic lateral sclerosis).

Pseudoathetosis: abnormal writhing movements (typically affecting the fingers) caused by a failure of proprioception.

Chorea: brief, semi-directed, irregular movements that are not repetitive or rhythmic but appear to flow from one muscle to the next. Patients with Huntington’s disease typically present with chorea.

Myoclonus: brief, involuntary, irregular twitching of a muscle or group of muscles. All individuals experience benign myoclonus on occasion (e.g. whilst falling asleep) however persistent widespread myoclonus is associated with several specific forms of epilepsy (e.g. juvenile myoclonic epilepsy).

Tardive dyskinesia: involuntary, repetitive body movements which can include protrusion of the tongue, lip-smacking and grimacing. This condition can develop secondary to treatment with neuroleptic medications including antipsychotics and antiemetics.

Hypomimia: a reduced degree of facial expression associated with Parkinson’s disease.

Ptosis and frontal balding: typically associated with myotonic dystrophy.
Ophthalmoplegia

Question 5

What objects should you look for around the bed before a lower limb neuro exam

Answer 5

Walking aids: the ability to walk can be impacted by a wide range of neurological pathology.

Prescriptions: prescribing charts or personal prescriptions can provide useful information about the patient’s recent medications.

Question 6

What is important to remember when assessing gait

Answer 6

Patients with neurological disease are often at an increased risk of falls so make sure to remain close to the patient during the assessment so that you are able to intervene if required.

Question 7

How do you assess gait

Answer 7

Ask the patient to walk to the end of the examination room and then turn and walk back whilst you observe their gait paying attention to:

Stance: a broad-based ataxic gait is typically associated with midline cerebellar pathology (e.g. a lesion in multiple sclerosis or degeneration of the cerebellar vermis secondary to chronic alcohol excess).

Stability: a staggering, slow and unsteady gait is typical of cerebellar pathology. In unilateral cerebellar disease, patients will veer towards the side of the lesion.

Arm swing: often absent or reduced in Parkinson’s disease (typically unilateral initially).

Steps: small, shuffling steps are characteristic of Parkinson’s disease. High-stepping may indicate the presence of foot drop.

Turning: patients with cerebellar disease will find the turning manoeuvre particularly difficult

Question 8

How do you assess tandem gait

Why do we assess this

Answer 8

Ask the patient to walk to the end of the examination room and back with their heels to their toes (known as ‘tandem gait’). Heel-to-toe walking exacerbates underlying unsteadiness making it easier to identify more subtle ataxia.

Tandem gait is particularly sensitive at identifying dysfunction of the cerebellar vermis (e.g. alcohol-induced cerebellar degeneration). Difficulties with heel-to-toe walking may also suggest weakness of the flexors muscles of the leg or sensory ataxia.

Question 9

What are the key gaits to look out for

Answer 9

ataxic
Parkinsonian
High-stepping
waddling
hemiparetic
spastic paraparesis

Question 10

What is an ataxic gait

Answer 10

Ataxic gait: broad-based, unsteady and associated with either cerebellar pathology or sensory ataxia (e.g. vestibular or proprioceptive dysfunction). In the context of proprioceptive sensory ataxia, patients typically watch their feet intently to compensate for the proprioceptive loss. If a cerebellar lesion is present the patient may veer to the side of the lesion.

Question 11

What is a Parkinsonian gait

Answer 11

small, shuffling steps, stooped posture and reduced arm swing (initially unilateral). The patient will require several small steps to turn around. The gait appears rushed (festinating) and may get stuck (freeze). Hand tremor may also be noticeable.

Question 12

What is a high-stepping gait

Answer 12

can be unilateral or bilateral and is typically caused by foot drop (weakness of ankle dorsiflexion). The patient also won’t be able to walk on their heel(s).

Question 13

What is a waddling gait

Answer 13

shoulders sway from side to side, legs lifted off ground with the aid of tilting the trunk. Waddling gait is commonly caused by proximal lower limb weakness (e.g. myopathy).

Question 14

What is a hemiparetic gait

Answer 14

one leg held stiffly and swings round in an arc with each stride (circumduction). This type of gait is commonly associated with individuals who have had a stroke.

Question 15

What is spastic paraparesis

Answer 15

similar to hemiparetic gait but bilateral, with both legs stiff and circumducting. The patient’s feet may be inverted and “scissor”.

This type of gait is typically associated with hereditary spastic paraplegia.

Question 16

What does Romberg’s test assess

Answer 16

Romberg’s test is used to assess for loss of proprioceptive or vestibular function (known as sensory ataxia). The test does not assess cerebellar function and instead is used to quickly screen for evidence of sensory ataxia (i.e. non-cerebellar causes of balance issues).

Question 17

What is Romberg’s test based on

Answer 17

Romberg’s test is based on the premise that a patient requires at least two of the following three senses to maintain balance whilst standing:

Proprioception: the awareness of one’s body position in space.
Vestibular function: the ability to know one’s head position in space.
Vision: the ability to see one’s position in space.

Romberg’s test involves removing the sense of vision by asking the patient to close their eyes. As a result, if the patient has a deficit in proprioception or vestibular function they will struggle to remain standing without visual input.

Question 18

How do you perform Romberg’s test

Answer 18

1. Position yourself within arms reach of the patient to allow you to intervene should they begin to fall.
2. Ask the patient to put their feet together and keep their arms by their sides (be aware that patients with truncal ataxia may struggle to do this, however, this type of unsteadiness is not the same as a positive Romberg’s sign).
3. Ask the patient to close their eyes.

Question 19

How do you interpret Romberg’s test

Answer 19

Falling without correction is abnormal and referred to as a positive Romberg’s sign. This indicates unsteadiness is due to sensory ataxia (i.e. a deficit of proprioceptive or vestibular function, rather than cerebellar function). Causes of proprioceptive dysfunction include joint hypermobility (e.g. Ehlers-Danlos syndrome), B12 deficiency, Parkinson’s disease and ageing (known as presbypropria). Causes of vestibular dysfunction include vestibular neuronitis and Ménière’s disease.

Swaying with correction is not a positive result and often occurs in cerebellar disease due to truncal ataxia.

Question 20

How do you assess lower limb tone

Answer 20

Leg roll and leg lift
Briefly assess tone in the muscle groups of the hip, knee and ankle on each leg, comparing each side as you go. Ask the patient to keep their legs fully relaxed throughout the assessment.

1. With the patient lying on the examination couch, roll each leg to assess tone in the muscles responsible for the rotation of the hip.
2. Lift each knee briskly off the bed (warning the patient first) and observe the movement of the leg. In patients with normal tone, the knee should rise whilst the heel remains in contact with the bed (the heel will typically lift off the bed if there is increased tone).

Question 21

What is clonus

Answer 21

Clonus is a series of involuntary rhythmic muscular contractions and relaxations that is associated with upper motor neuron lesions of the descending motor pathways (e.g. stroke, multiple sclerosis, cerebral palsy).

Question 22

How do you assess ankle clonus

Answer 22

1. Position the patient’s leg so that the knee and ankle are slightly flexed, supporting the leg with your hand under their knee, so they can relax.
2. Rapidly dorsiflex and partially evert the foot to stretch the gastrocnemius muscle.
3. Keep the foot in this position and observe for clonus. Clonus is felt as rhythmic beats of dorsiflexion and plantarflexion. If more than 5 beats of clonus are present, this would be classed as an abnormal finding.

Question 23

How do you assess power in hip flexion

Give the myotome and muscles assessed as well as instructions

Answer 23

Myotome assessed: L1/2

Muscles assessed: iliopsoas

Instructions: Ask the patient to raise their leg off the bed and apply downward resistance over the anterior thigh: “Lift your leg off the bed and don’t let me push your leg down.”

Question 24

How do you assess power in hip extension

Give the myotome and muscles assessed as well as instructions

Answer 24

Myotome assessed: L5/S1/S2 (inferior gluteal nerve)

Muscles assessed: gluteus maximus

Instructions: Place your hand under the patient’s thigh and ask them to resist you trying to lift their leg: “Don’t let me lift your leg off the bed.”

Question 25

How do you assess power in knee flexion

Give the myotome and muscles assessed as well as instructions

Answer 25

Myotome assessed: S1 (sciatic nerve)

Muscles assessed: hamstrings

Instructions: Ask the patient to flex their knee so that their foot is flat on the bed and then apply resistance by pulling the lower leg towards you: “Bend your knee so that your foot is flat on the bed and then don’t let me pull your leg towards me.”

Question 26

How do you assess power in knee extension

Give the myotome and muscles assessed as well as instructions

Answer 26

Myotome assessed: L3/4 (femoral nerve)

Muscles assessed: quadriceps

Instructions: With the patient’s knee still flexed, position your hand over the anterior portion of the lower leg and ask the patient to try and straighten their leg: “Try and straighten your leg whilst I try to stop you.”

Question 27

How do you assess power in ankle dorsiflexion

Give the myotome and muscles assessed as well as instructions

Answer 27

Myotome assessed: L4/5 (deep peroneal nerve)

Muscles assessed: tibialis anterior

Instructions: Ask the patient to position their legs flat on the bed, dorsiflex their foot and resist you trying to push their foot downwards: “Put your legs flat on the bed, cock your foot backwards and don’t let me push your foot down.”

Question 28

How do you assess power in ankle plantarflexion

Give the myotome and muscles assessed as well as instructions

Answer 28

Myotome assessed: S1/2 (tibial nerve)

Muscles assessed: gastrocnemius, soleus

Instructions: With the patient’s legs still flat on the bed, ask them to plantarflex their foot and resist you trying to pull their foot upwards: “Point your foot downwards like you’re pushing a car pedal and don’t let me pull it up.”

Question 29

How do you assess power in hallux extension

Give the myotome and muscles assessed as well as instructions

Answer 29

Myotome assessed: L5 (deep peroneal nerve)

Muscles assessed: extensor hallucis longus

Instructions: With the patient’s legs still flat on the bed, ask them to extend their big toe and resist you trying to push it down: “Point your big toe up towards your head and don’t let me push it down.”

Question 30

What patterns of weakness should you look out for in the neuro lower limb exam

Answer 30

Upper motor neuron lesions cause a ‘pyramidal’ pattern of weakness that disproportionately affects lower limb flexors and upper limb extensors (i.e. lower limb flexors are weaker than extensors in a lower limb neurological assessment).

Lower motor neuron lesions cause a focal pattern of weakness, with only the muscles directly innervated by the damaged neurones affected.

Question 31

How do you assess the knee jerk reflex

Answer 31

1. Remove the weight from the patient’s lower limb by either supporting it or asking the patient to hang their legs over the side of the bed. Ensure the patient’s lower limb is completely relaxed before assessing the knee-jerk reflex.
2. Tap the patellar tendon with the tendon hammer (making sure to hold the tendon hammer handle at its end to allow gravity to aid a good swing).
3. If a reflex appears absent make sure the patient is fully relaxed and then perform a reinforcement manoeuvre.

Question 32

What nerves are tested in knee jerk reflex

ankle jerk?

Answer 32

L3,4

S1,2

Question 33

Give a mnemonic for remembering everything you should look for in a neuro exam (upper or lower limb)?

Answer 33

DWARFS
Deformation
Wasting
Asymmetry
Rigidity
Fasciculations
Spasticity/ scars

Question 34

Give a mneumonic to remember the most common causes of peripheral neuropathy

Answer 34

The mnemonic DANG THERAPIST is helpful in recalling the more common causes of
peripheral neuropathy:

Diabetes Mellitus
Alcohol
Nutritional (B12 deficiency)
Guillain-Barre Syndrome
Toxins (Pb, As, Zn, Hg)
Hematologic (paraproteins)
Endocrine (hypothyroid)
Rheumatologic (SLE, rheumatoid arthritis, vasculitis)
Amyloid
Porphyria
Infectious (syphilis, HIV)
Sarcoid
Tumor (paraneoplastic neuropathy)