• rapid (<72/24) onset of facial paralysis - may be preceded by a slight fever, pain behind the ear on the affected side, a stiff neck, and weakness and/or stiffness on one side of the face.
• unilateral paralysis is complete vs stroke which does NOT include forehead paralysis due to crossing of innervation
• may have loss of taste on one side of mouth, drooling, and an increased sensitivity to sound (hyperacusis)
• usually results from ischemia and/or compression of CN VII
• exact cause not known - viral and auto-immune frequently implicated. There appears to be an inherited tendency
• usually resolves - 2/52
• Prednisolone if presents ≤72/24. No consensus on dosage but 2 possible regimens:
  • 50 mg daily for 10/7 or
  • 60 mg daily for 5/7 followed by a daily reduction in dose of 10 mg (for a total treatment time of 10/7) if a reducing dose is preferred.
• Differential:
  • acoustic neuroma - due to associated compression of the neuroma on VII
  • Myasthenia Gravis
  • Ramsay-Hunt syndrome - due to Varicella zoster. Look for associated rash

rare neurological disorder caused by varicella zoster characterized by paralysis of CN-VII with variable presentation of other findings:

• erythematous & vesicular rash affecting the pinna and sometimes external auditory canal and occasionally the soft palate and pharynx.
• may be associated with tinnitus and hearing loss.
• Treatment with antivirals ≤72/24 + other symptomatic Rx

• Compression of the brachial plexus which can occur between the anterior and middle scalene muscles, underneath a cervical rib, beneath the pectoralis minor tendon, or by fibrous bands anywhere along the course of the plexus.
• scalenus anticus syndrome: abnormal insertion of scalenus anterior onto 1st rib (commonest cause)
• congenital cervical rib
• bony abnormality of 1st rib or clavicle (congenital anomaly, malunited fracture, callus, Paget disease, tumour)
• elongated C7 transverse process
• muscle hypertrophy
• fibrous bands
• supraclavicular tumour or lymphadenopathy

• Differentials - other causes of brachial plexopathy including trauma, mass lesions, vascular lesions, brachial plexitis, and cervical spinal cord or foraminal stenosis

subtypes:

• arterial thoracic outlet syndrome (ATOS)
• neurogenic thoracic outlet syndrome (NTOS)
• venous thoracic outlet syndrome (VTOS)
• neurogenic pectoralis minor Syndrome (NPMS)
• venous pectoralis minor syndrome (VPMS)
• arterial pectoralis minor syndrome (APMS)

Neurogenic TOS (95% of all TOS) presents with pain, weakness, numbness and tingling in the hand and arm.

• neck pain and headache in the back of the head are common.
• usually caused by neck trauma - whiplash injuries or repetitive stress injury at work commonly initiate symptoms. The original injury said to cause over-stretching of the neck muscles which heal by forming irritative scar tissue

Venous TOS, also known as Paget-Schroetter disease, presents with arm swelling, blue or dark discolouration, and a feeling of fullness or aching in the arm

• usually an anatomical variation leading to compression or thrombosis (Paget-Schroetter disease)

Arterial TOS presents with coldness, numbness, tingling, pain, and white discolouration in the fingers or whole hand.

• Cramping of the forearm and hand with activity (claudication) is common.
• Pain usually involves the hand and arm, but not the neck or shoulder.
• more commonly related to thrombus

Useful tests:

• Wright test - hyperabduction leading to increased pain or loss of pulse in vascular TOS
• Adson test - ipsilateral head rotation and inspiration leading to increased pain or loss of pulse in vascular TOS.

(Parsonage-Turner Syndrome)

• otherwise known as idiopathic or hereditary neuralgic amyotrophy
• uncommon, characterized by severe shoulder pain followed by patchy muscle paralysis and sensory loss involving the shoulder girdle and upper extremity.
• any nerve or branch within the brachial plexus can be involved
• auto-immune and biomechanical causes implicated
• ultimately inflammatory processes predominate
• lower trunk worse prognosis c/w upper trunk
• recovery over many months - 2/3 have motor function ≤1/12

• Often in stages
  • sudden severe pain - may last weeks
  • painless flaccid paralysis - more often upper branches
  • slow recovery over months - 6-18/12 recovery period for motor function

• Cervical spine radiculopathy - pain and weakness follows a specific nerve root distribution
• Rotator cuff pathology - shoulder pain persists despite development of shoulder weakness
• Entrapment neuropathy - shoulder pain with progressive weakness in a specific peripheral nerve distribution
• Idiopathic hypertrophic brachial neuritis (IHBN) - rare and painless. Characterized by weakness in upper limb muscles and hypertrophy of the brachial plexus

• Groin pain of neural origin can be caused by pelvic surgeries, blunt trauma, sports injury, hypertrophy of the abdominal muscles from excessive training, or from unknown causes
• genitofemoral and lateral femoral cutaneous nerve entrapments can result from tight clothing
• Obturator nerve entrapment can be caused by pelvic trauma and tumours or normal pregnancy
• Among athletes, most cases of entrapment of the ilioinguinal nerve are linked to hypertrophy of the abdominal muscles as a result of excessive training
• Iliohypogastric nerve injury combined with tears in the external oblique aponeurosis has been described in soccer and rugby players
• In athletes, obturator nerve entrapment appears to be the result of a fascial band at the distal end of the obturator canal, esp in skaters, Australian Rules football players, and soccer players as a result of adductor muscle development

a condition due to deficiency of Thiamine (vit B1)

• Dry Beriberi - neurological symptoms
• Wet Beriberi - Cardiac symptoms with or without neurology
• infantile Beriberi - neurocardiac symptoms in infant <1/12
• sensorimotor neuropathy of dry Beriberi can mimic the signs and symptoms of acute or chronic GBS.
• mild-to-moderate reduction in all sensory modalities in a stocking distribution with reduced reflexes.
• may have mild, predominantly distal weakness.
• Wet beriberi can present with fulminant CVS collapse with overload and severe lactic acidosis which rapidly responds to Thiamine replacement
• Thiamine deficiency:
  • reduced thiamine intake - alcohol abuse, anorexia nervosa, dieting, or malabsorption following bariatric surgery
  • Malabsorption - diarrhea, celiac disease, tropical sprue, or dysentery.
  • Other - burns, pregnancy, dialysis, and malignancy
• Thiamine repletion leads to rapid clinical improvement in dry beriberi c/w Guillain Barré Syndrome

Red flags:

• Severe low back pain (LBP)
• Sciatica: often bilateral but sometimes absent, especially at L5/S1 with an inferior sequestration
• Saddle and/or genital sensory disturbance
• Bladder, bowel and sexual dysfunction

• Mostly commonly large lumbar disc herniation
• Less common - epidural haematoma, infections, malignancy, trauma

3 main variations:

1. Rapid onset without a previous history of back problems.
2. Acute bladder dysfunction with a history of low back pain and sciatica.
3. Chronic backache and sciatica with gradually progressing CES often with canal stenosis.

Important to distinguish between Complete and Incomplete as CES-Incomplete has a good prognosis with emergency surgical intervention. CES-Complete does not respond as well and surgery may even be delayed:

• CES-Incomplete
  • urinary difficulties of neurogenic origin including altered urinary sensation
  • loss of desire to void, poor urinary stream and the need to strain in order to micturate
  • Saddle and genital sensory deficit is often unilateral or partial
  • trigone sensationclose an inflated urinary catheter is gently pulled and should elicit the desire to micturate should be present.
• CES-Complete
  • painless urinary retention and overflow incontinence (CES-Retention)
  • There is usually extensive or complete saddle and genital sensory deficit
  • deficient trigone sensation.

Lumbar Plexus N entrapment syndromes - groin pain in athletes
https://www.orthobullets.com/shoulder-and-elbow/3065/brachial-neuritis-parsonage-turner-syndrome
https://basicmedicalkey.com/summary-of-cranial-nerves/
https://cks.nice.org.uk/topics/bells-palsy/
Cauda equina review 2011
https://rarediseases.org/rare-diseases/thoracic-outlet-syndrome/
J NeuroSurg. Thoracic Outlet synd 2015