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PACES 2024 > Station 3: Neuro (Upper Limbs) > Flashcards

Station 3: Neuro (Upper Limbs) Flashcards

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1
Q

Unilateral hand wasting -> what to look for next?

A

Thenar wasting?

Hypothenar or intrinsic muscle wasting?

Both groups wasted?

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2
Q

unilateral hand wasting with only thenar wasting

A

Hand of Benediction sign: proximal Median nerve damage

Carpal tunnel syndrome

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3
Q

unilateral hand wasting with hypothenar/ intrinsic muscle wasting

A

usually ulnar nerve neuropathy

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4
Q

unilateral hand wasting, with intrinsic muscles, hypothenar and thenar eminence wasting

how to differentiate between C8-T1 segment vs median and ulnar neuropathy

A

finger extension should be weak in C8-T1 segment involvement

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5
Q

unilateral hand wasting, with intrinsic muscles, hypothenar and thenar eminence wasting
- causes
​

A

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)

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6
Q

what is the course of the radial nerve and its branches?

A

nerve roots: C5-T1
emerges from the posterior cord of the brachial plexus

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7
Q

features of a radial nerve palsy that is affected at the wrist?
ie. superficial radial nerve palsy aka Watenberg syndrome

A

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

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8
Q

features of radial nerve palsy injured at lower 1/3 humerus to proximal forearm?

A

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

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9
Q

features of radial nerve palsy injured at middle 2/3 humerus along the spiral groove?

A

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

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10
Q

features of radial nerve palsy injured at
upper 1/3 humerus?

A

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

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11
Q

once radial palsy is detected, proceed to look for level of lesion, what to examine for?

A
  • 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

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12
Q

causes of radial nerve palsy?

A

trauma from accident/ surgery
compression, entrapment
part of mononeuritis multiplex
lead poisoning

other causes, e.g. finger drop could be 2’ synovitis from RA

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13
Q

ix of radial nerve palsy?

A

detailed history for cause
X-ray : evaluate for fracture, tumour, healing callus

NCS, EMG to locate level of injury and to monitor recovery progress

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14
Q

management of radial nerve palsy?

A

education and counselling
PTOT: wrist splint, cock up splint for finger drops
surgical decompression of entrapment

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15
Q

prognosis of radial nerve palsy if neuropraxia with no disruption to the sheath or the axon?

A

recovery complete and rapid (weeks)

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16
Q

prognosis of radial nerve palsy if axonotmesis with disruption of axon but intach schwann sheath?

A

recovery complete but slower (1mm/day)

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17
Q

prognosis of radial nerve palsy with complete transection of the nerve?

A

recovery is incomplete

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18
Q

what is the course of the median nerve and its branches?

A

formed by lateral (C5-7) and medial (C8, T1) cords of the brachial plexus

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19
Q

features of median nerve palsy if injured at level of wrist?

A

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

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20
Q

features of median nerve palsy if injured superifically at level of forearm

A

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)

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21
Q

features of median nerve palsy if injured proximally

A

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

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22
Q

median nerve palsy: how to screen for involvement of radial and ulnar nerve involvement?

A

radial nerve: test wrist and elbow extension

ulnar nerve: finger abduction, Froment’s sign

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23
Q

median nerve palsy: what to examine for to suggest underlying cause

A

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

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24
Q

oschner test

A

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.

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25
causes of median nerve palsy?
trauma iatrogenic: surgical compression mononeuritis multiplex infection-leprosy inflammatory- CIDP ischaemic- vasculitis
26
causes of carpal tunnel syndrome
idiopathic pregnancy, OCPs endocrine- acromegaly, hypothyroidism Hands; RA, gout, TB tenosynovitis, OA of carpus amyloidosis, sarcoidosis
27
management of median nerve palsy?
education OT, wrist splint medications- treatment of underlying disease, IA steroid, withdrawing OCPs surgical decompression
28
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
29
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
30
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
31
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
32
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
33
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
34
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
35
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
36
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
37
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
38
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
39
management of ulnar nerve palsy?
education and avoidance of resting on elbow PTOT Medical- analgesia Surgical decompression with anterior transposition of the nerve
40
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
41
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)
42
Unilateral UL weakness, UMN pattern of weakness
cortical subcortical brainstem hemicord
43
bilateral UL weakness with UMN pattern of weakness
spinal cord lesion (myelopathy, compression, infarct) bilateral brainstem bilateral subcortical bilateral cortical
44
UL weakness, LMN pattern of weakness, proximal weakness with abnormal sensation
GBS CIDP Syringomyelia
45
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
46
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)
47
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
48
what special tests if suspecting myotonic dystrophy?
percussion myotonia of the thenar eminence myotonic grasp
49
reflexes and sensation in myotonic dystrophy?
reflexes reduced sensation normal
50
X linked muscular dystrophy pseudohypertrophy of calves Gowers sign, proximal weakness cardiomyopathy
Duchenne's, Becker's (less severe form, later onset)
51
Autosomal recessive muscular dystrophy shoulder and pelvic girdle affected usually 30s sparing of face and heart
limb girdle muscular dystrophy
52
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
53
what is myotonia?
continued contraction of the muscles after voluntary contraction ceases, followed by impaired relaxation
54
autosomal dominant disorder myotonia, weakness, no sensory loss
myotonic dystrophy
55
what other organ systems may be affected in myotonic dystrophy?
intellectual disability cataracts dilated CMP, conduction defects testicular atrophy, gynaecomastia DM nodular thyroid enlargement
56
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
57
58
differentials for dissociated sensory loss?
anterior spinal artery occlusion (Affects spinothalamic tract) DM neuropathy, leprosy, hereditary amyloidotic polyneuropathy
59
DDx for syringomyelia?
haematomyelia intramedullary tumours of the spinal cord spinal cord injuries cranioverterbral anomalies
60
associated abnormalities of syringomyelia?
arnold chiari malformation bony defects around the foramen magnum hydrocephalus spina bifida spinal cord tumours
61
ix syringomyelia?
MRI spinal cord
62
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
63
what is syringobulbia?
syrinx in the medulla of the brainstem usually extension of the syringomyelia but can be isolated
64
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
65
Huntington's disease?
young adult, chorea, dementia autosomal dominant pattern
66
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
67
extra pyramidal side effects of antipsychotics?
acute dystonia (oculogyric) parkinonism akathisia (restless legs syndrome) tardive dyskinesia (orofacial dyskinesia)

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