Station 3: Neuro (Upper Limbs) Flashcards
Unilateral hand wasting -> what to look for next?
Thenar wasting?
Hypothenar or intrinsic muscle wasting?
Both groups wasted?
unilateral hand wasting with only thenar wasting
Hand of Benediction sign: proximal Median nerve damage
Carpal tunnel syndrome
unilateral hand wasting with hypothenar/ intrinsic muscle wasting
usually ulnar nerve neuropathy
unilateral hand wasting, with intrinsic muscles, hypothenar and thenar eminence wasting
how to differentiate between C8-T1 segment vs median and ulnar neuropathy
finger extension should be weak in C8-T1 segment involvement
unilateral hand wasting, with intrinsic muscles, hypothenar and thenar eminence wasting
- causes
medial and ulnar nerve neuropathy: either simple compression, mononeuritis multiplex, multifocal motor neuropathy
C8/T1 segment: which also involves weak finger extension
- can be due to brachial plexopathy, cord involvement at C8/T1, Anterior horn cell (but with normal sensation), nerve root (associated with radicular symptoms)
what is the course of the radial nerve and its branches?
nerve roots: C5-T1
emerges from the posterior cord of the brachial plexus
features of a radial nerve palsy that is affected at the wrist?
ie. superficial radial nerve palsy aka Watenberg syndrome
the radial nerve continues as the superficial radial nerve which provides sensory innervation of the posterior aspect of the radial 3.5 digits (pure sensory)
pain and numbness over first web space dorsally (bc of overlap)
no motor weakness
features of radial nerve palsy injured at lower 1/3 humerus to proximal forearm?
posterior interosseous nerve affected (pure motor): supplies all the extensors of the forearms including APL and supinator except the extensor carpi radialis longus
Motor: finger drop
extensors of the fingers at the MCPJ affected
wrist drop not a feature as the extensor carpi radialis longus is intact
features of radial nerve palsy injured at middle 2/3 humerus along the spiral groove?
radial nerve pierces the intermuscular septum at lower third of humerus to enter the anterior compartment of arm to supply brachioradialis
Brachioradialis weak
Wrist drop
Finger drop (weak finger extensors)
triceps reflex preserved, triceps intact
features of radial nerve palsy injured at
upper 1/3 humerus?
motor:
weak triceps - elbow extension
weak brachioradialis
weak wrist extension (wrist drop)
weak finger extension (finger drop)
weak thumb extension
Reflex: triceps jerk affected
sensation: dorsum of lateral 3.5 fingers
anatomical snuffbox innervated by superifical branch of radial nerve
once radial palsy is detected, proceed to look for level of lesion, what to examine for?
- demonstrate weakness of extension at MCPJ
- weakness of wrist extension
- brachioradialis
- test triceps muscle
- triceps jerk
- look for reduced sensation over anatomical snuffbox
- inspect forearm, elbow, humerus, shoulder for scars
- test function (fine motor, coarse)
preservation of IPJ extension (lumbricals, interossei)
screen for median nerve involvement: thumb abduction, oschner’s clasping test
screen for ulnar nerve involvement: finger abduction, froment’s sign
causes of radial nerve palsy?
trauma from accident/ surgery
compression, entrapment
part of mononeuritis multiplex
lead poisoning
other causes, e.g. finger drop could be 2’ synovitis from RA
ix of radial nerve palsy?
detailed history for cause
X-ray : evaluate for fracture, tumour, healing callus
NCS, EMG to locate level of injury and to monitor recovery progress
management of radial nerve palsy?
education and counselling
PTOT: wrist splint, cock up splint for finger drops
surgical decompression of entrapment
prognosis of radial nerve palsy if neuropraxia with no disruption to the sheath or the axon?
recovery complete and rapid (weeks)
prognosis of radial nerve palsy if axonotmesis with disruption of axon but intach schwann sheath?
recovery complete but slower (1mm/day)
prognosis of radial nerve palsy with complete transection of the nerve?
recovery is incomplete
what is the course of the median nerve and its branches?
formed by lateral (C5-7) and medial (C8, T1) cords of the brachial plexus
features of median nerve palsy if injured at level of wrist?
median nerve enters the carpal tunnel and supplies LOAF (lateral 2 lumbricals, opponens policis, abductor pollicis brevis, flexor pollicis brevis) and sensory branch to the lateral 3.5 fingers
->
wasting of thenar muscles
externally rotated thumb
weak abduction of thumb
Tinel’s and Phalen’s positive in carpal tunnel
sensory loss of the lateral 3.5 fingers
features of median nerve palsy if injured superifically at level of forearm
gives off the anterior interosseous nerve in the forearm which supplies the flexor pollicis longus (flexion of the DIPJ thumb), flexor digitiorum profundus of lateral 2 fingers (flexion of DIPJ), pronator quadratus
-> AIN syndrome
no sensory loss
weak pinch sign (due to weakness of flexor pollicis longus and digitorum profundus)
features of median nerve palsy if injured proximally
median nerve supplies all the muscles of the forearm except the flexor carpi ulnaris and the ulnar half of the flexor digitorum profundus and LOAF
motor:
wasting of thenar eminence
thumb externally rotated
Hand of benediction
oschner’s clasping test
weak thumb abduction, opposition, flexion
Weak MCPJ flexion and IPJ extension by lumbricals
Weak wrist flexion by flexor carpi radialis
no reflexes affected
sensation: palm of lateral 3.5 fingers
median nerve palsy: how to screen for involvement of radial and ulnar nerve involvement?
radial nerve: test wrist and elbow extension
ulnar nerve: finger abduction, Froment’s sign
median nerve palsy: what to examine for to suggest underlying cause
Tinel’s phalens for carpal tunnel syndrome
Look for signs of scars, RA hands, acromegaly, pregnancy, hypothyroidism
Look at wrist, forearm, elbow, arm, axilla for scars
oschner test
Ochsner’s clasping test assesses the function of the median nerve for lesions in the cubital fossa or above, by testing for the function of flexor digitorum superficialis.
The patient is asked to clasp his hands together. Inability to flex the index finger confirms a lesion on that side.
causes of median nerve palsy?
trauma
iatrogenic: surgical
compression
mononeuritis multiplex
infection-leprosy
inflammatory- CIDP
ischaemic- vasculitis
causes of carpal tunnel syndrome
idiopathic
pregnancy, OCPs
endocrine- acromegaly, hypothyroidism
Hands; RA, gout, TB tenosynovitis, OA of carpus
amyloidosis, sarcoidosis
management of median nerve palsy?
education
OT, wrist splint
medications- treatment of underlying disease, IA steroid, withdrawing OCPs
surgical decompression
what is the anatomical course of the ulnar nerve?
medial cord of the brachial plexus (C8, T1)
provides motor to all muscles of the hands except the LOAD, flexor carpi ulnaris and flexor digitorum profundus to 4th and 5th fingers
sensory to ulnar 1.5 fingers
features of ulnar nerve injury at level of wrist
hypothenar eminence wasting
pronounced claw hand
froment’s sign positive
weakness of finger abduction
loss of sensation to medial 1.5 fingers
features of ulnar nerve injury at forearm?
wasting of hypothenar muscles and small muscles of hand
less severe ulnar claw hand (Ulnar paradox)
weak DIPJ of little finger
weak flexor carpi ulnaris tendon on flexion of wrist
weak finger abduction, adduction
weak flexion of 4th and 5th fingers
Froments sign positive (weakness of adductor pollicis)
sensory loss to medial 1.5 fingers
what is the ulnar claw hand?
hyperextension of the 4th and 5th MCPJ associated with flexion of the IPJs at 4th and 5th fingers
due to unopposed long extensors of the 4th and 5th fingers in contrast to the index and middle finger which are counteracted by the lumbricals which are served by the median nerve
what is the ulnar paradox?
ulnar claw deformity is more pronounced for lesions distally
this is because a more proximal lesion at the elbow also causes weakness of the ulnar half of the flexor digitorum profundus, resulting in less flexion of the IPJs at the 4th and 5th fingers
how to differentiate ulnar nerve palsy vs T1 lesion?
motor: in T1 lesions, thenar eminence will also be wasted
sensory: loss of T1 dermatomal distribution
ulnar nerve palsy what to rule out?
rule out median nerve involvement: thumb abduction, oschners test
radial nerve involvement: wrist and elbow extension
T1 sensory loss
ulnar nerve palsy what are some examination fingers which may suggest aetiology?
elbow scars, cubitus valgus deformity
compression at Guyon’s canal at the wrist (spares sensory)
Compression at cubital tunnel by 2 heads of the flexor carpi ulnaris
hypopigemented patch finger resorption, thickened nerves suggestive of leprosy
what is Froment’s sign
patient asked to grasp a piece of paper between thumb and lateral aspect of index finger
the affected thumb will flex as adductor pollicis muscles are weak
causes of ulnar nerve palsy?
compression or entrapment (Guyons canal at wrist, Cubital tunnel at elbow)
trauma
surgical
mononeuritis multiplex
infection- leprosy
ischaemia- vasculitis
inflammatory- CIDP
ix of ulnar nerve palsy?
Bloods: HbA1c to rule out DM
X ray of elbow and wrist
KIV C spine if suspected T1 involvement
EMG and NCS to locate level of injury and monitor recovery progress
management of ulnar nerve palsy?
education and avoidance of resting on elbow
PTOT
Medical- analgesia
Surgical decompression with anterior transposition of the nerve
bilateral wasted hands with wasting of hypothenar and thenar muscles + intrinsic muscles of the hand
C8/T1 lesion:
Cervical spondylosis -> radicular pain
Anterior horn cell like MND or polio: No pain or sensory loss
Cord: C8/T1 myelopathy, syringomyelia, Transverse myelitis
Peripheral neuropathy:
if LL affected with glove and stocking sensory loss, then think of diffuse peripheral neuropathy
if LL ok, maybe mononeuritis multiplex (sensory loss in the pattern of nerves), multifocal motor nueropathy
unilateral wasted hands, what possible causes
cervical cord
anterior horn cell: poliomyelitis
C8-T1 root lesions (cervical spondylosis)
brachial plexus (Trauma, cervical rib, tumour, radiation)
Peripheral nerve (median, ulnar, combined; asymmetric peripheral neuropathy)
Unilateral UL weakness, UMN pattern of weakness
cortical
subcortical
brainstem
hemicord
bilateral UL weakness with UMN pattern of weakness
spinal cord lesion
(myelopathy, compression, infarct)
bilateral brainstem
bilateral subcortical
bilateral cortical
UL weakness, LMN pattern of weakness, proximal weakness with abnormal sensation
GBS CIDP
Syringomyelia
what is syringomyelia?
cavity formation with presence of a large fluid filled cavity in the grey matter of the cervical spinal cord which is in communication with the central canal and contains CSF
triad of LMN weakness in ULs, dissociated sensory loss in the ULs and UMN weakness in LLs
features of syringomyelia?
at the level of the syrinx:
LMN anterior horn cells affected -> flaccid weakness
dissociated sensory loss: loss of pinprick but intact sensation to vibration and propioception
below level of syrinx: affects corticospinal tracts, so spastic paraparesis of LLs
extension into cervical cord and medulla
- horner’s syndrome
- bulbar palsy (CN X-XII)
- ataxia and nystagmus (affects medial longitudinal bundle if lesion from C5 upwards)
- onion skin pattern loss of pain in the face (spinal nucleas of V CN which extens from pons to the upper cervical cord)
causes of proximal myopathy?
congenital/ inherited: Myotonic dystrophy, fascioscapulohumeral dystrophy, Becker’s, LImb girdle muscular dystrophy, oculopharyngeal muscular dystrophy
endocrine/ metabolic: cushings syndrome, thyroid disease, ESRF, lactic acidosis, periodic hypokalaemic paralysis
inflammatory/ immune: poly/dermatomyositis
infection: HIV
drugs (statins, fibrates), alcohol
mitochondrial myopathy - CPEO, mcardle’s syndrome
what special tests if suspecting myotonic dystrophy?
percussion myotonia of the thenar eminence
myotonic grasp
reflexes and sensation in myotonic dystrophy?
reflexes reduced
sensation normal
X linked muscular dystrophy
pseudohypertrophy of calves
Gowers sign, proximal weakness
cardiomyopathy
Duchenne’s, Becker’s (less severe form, later onset)
Autosomal recessive muscular dystrophy
shoulder and pelvic girdle affected
usually 30s
sparing of face and heart
limb girdle muscular dystrophy
autosomal dominant muscular dystrophy
bilateral symmetrical weakness of facial muscles and SCM with bilateral ptosis
weakness of shoulder muscles and later the pelvic girdle muscles
fascioscapulohumeral muscular dystrophy
what is myotonia?
continued contraction of the muscles after voluntary contraction ceases, followed by impaired relaxation
autosomal dominant disorder
myotonia, weakness, no sensory loss
myotonic dystrophy
what other organ systems may be affected in myotonic dystrophy?
intellectual disability
cataracts
dilated CMP, conduction defects
testicular atrophy, gynaecomastia
DM
nodular thyroid enlargement
how to ix myotonic dystrophy?
**confirm diagnosis: **
genetic testing
EMG - dive bomber pattern ie waxing and waning of potentials
muscle biopsy shows no inflammatory changes
muscle enzymes are normal
screen for complications:
Fasting glucose- screen for DM
ECG: conduction defect
CXR- cardiomegaly
Slit lamp for cataracts
differentials for dissociated sensory loss?
anterior spinal artery occlusion (Affects spinothalamic tract)
DM neuropathy, leprosy, hereditary amyloidotic polyneuropathy
DDx for syringomyelia?
haematomyelia
intramedullary tumours of the spinal cord
spinal cord injuries
cranioverterbral anomalies
associated abnormalities of syringomyelia?
arnold chiari malformation
bony defects around the foramen magnum
hydrocephalus
spina bifida
spinal cord tumours
ix syringomyelia?
MRI spinal cord
management of syringomyelia?
drainage of the syrinx to the subarachnoid space
syringoperitoneal drainage
- in AC malformation, cervical laminectomy and removal of lower central portion of the cervical bone
- intramedullary tumour excision
what is syringobulbia?
syrinx in the medulla of the brainstem
usually extension of the syringomyelia but can be isolated
features of syringobulbia?
horner’s
ataxia, nystagmus
Bulbar palsy
CN V, VII, IX, X
Onion skin pattern of loss of pain sensation of the face
Huntington’s disease?
young adult, chorea, dementia
autosomal dominant pattern
causes of choreathetosis?
Congenital: Huntington’s chorea, wilsons disease
endocrine/ metabolic: hyperthyroidism, post hyperglycaemia
inflammatory/ immune: SLE
vascular: globus pallidus stroke
infection: rheumatic fever, post encephalitis
drugs: L dopa, phenytoin, neuroleptics
toxins: CO poisoning
extra pyramidal side effects of antipsychotics?
acute dystonia (oculogyric)
parkinonism
akathisia (restless legs syndrome)
tardive dyskinesia (orofacial dyskinesia)
