Neurology pdf - د. بشار

Fifth stage

Medicine

Lec-12

د.بشار

17/4/2016

Diseases of Peripheral Nerves

Numerous inherited and acquired pathological processes may affect the nerve roots
(radiculopathy), the nerve plexuses (plexopathy) and/or the individual nerves (neuropathy).

Cranial nerves 3-12 share the same tissue characteristics as peripheral nerves elsewhere and
are subject to the same range of diseases. Nerve fibres of different types (motor, sensory or
autonomic) and of different sizes may be variably involved. Disorders may be primarily
directed at the axon, the myelin sheath (Schwann cells) or the vasa nervorum

PATTERN OF INVOLVMENT:

Mononeuropathy Simplex=Single Nerve

Mononeuropathy Multiplex=Several Nerves Randomly &Noncontiguously

Polyneuropathy( Peripheral Neuropathy)=Dysfunction of Numerous Peripheral Nerves at the
Same Time leading to predominantly distal & symmetrical deficit usually affecting lower
more than upper limbs

Types &Causes of peripheral neuropathy لالطالع

Diseases of Peripheral Nerves

SYMPTOMS &SIGNS

1.Sensory Disturbances

A.Numbness, Hyperpathia, Impaired Sensation &

SPONTANEOUS PAIN esp. in SMALL FIBER

involvement ;D. M. , Porphyria, AIDS, Alcoholic,

Entrapment …..

B. Dissociated Sensory Loss

Small Fib. Pain &Temp.

Large Fib. Touch, Vib. & Position

2. MOTOR DEFICITS

Weakness , Wasting , Fasciculation

Diminished or Absent Reflexes

i.e. LMNL

3.AUTONOMIC DISTURBANCES

Post. Hypotension, Coldness, Imp. Sweating, Impotence….esp. GBS, Diabetes, Renal
Failure, Porphyria….

4. ENLARGED NERVES

Leprosy, Amyloidosis, HSMN, Refsum Dis., Acromegaly..

Causes of P. N:

1. Inflammatory: GBS , CIPD

2. Metabolic &Nutritional :D.M. ,Uremia, Liver Failure, Hypothyroidism, Acromegaly, B12
Deficiency….

3.Infectious &Granulomateous:AIDS, Leprosy, Diphtheria, Sarcoidosis…

4.Vasculitis: PAN, SLE, Rh.Arthritis…

5.Neoplastic &Paraneoplastic

6. Drugs &Toxins:Alcohol, INH, Vinicristine, Phenytoin, Heavy Metals….

7.Hereditory:HSMN, HSN, Refsum Disease,Porphyria..

8. IDIOPATHIC

Drugs causing peripheral neuropathy لالطالع

EVALUATION OF PATIENTS:

TIME COURSE=Acute; Inflamm., Infectious, Toxins…

Chronic;Hereditory, Metabolic…

AGE= Early; Hereditory

Late; Metabolic, Neoplastic

OCCUPATION= Exposure to toxins

MEDICAL HISTORY

DRUGS

FAMILY HISTORY

DIFFERENTIALDIAGNOSIS:

 Diseases of muscles &n.m. junction  normal sensation& tendon reflexes
 Diseases of spinal cord  pyramidal signs &sensory level below the lesion

 Radiculopathies  dermatomal &myotomal distribution

INVESTIGATIONS:

 CONFIRM DIAGNOSIS

EMG = DENERVATION

ENG &NCV = Demyelination or Axonal Degeneration

 REVEAL UNDERLYING CAUSE

INVESTIGATION OF PERIPHERAL NEUROPATHY لالطالع

TREATMENT:

UNDERLYING CAUSE

NURSING CARE ? ULCERS &CONTRACTURES

RESPIRATORY MONITORING &MANAGEMENT

CARE OF SKIN &NAILS

RELIEF OF PAIN ----Lancinating Pain-- PHENYTOIN

CARBAMAZEPINE

MEXILETINE

Constant Pain----AMITRIPTYLINE

GABAPENTINE

GUILLIAN BARIE SYNDROME
ACUTE ASCENDING POLYRADICLONEUROPATHY

This syndrome of acute paralysis develop in 70 % of patients 1-4 weeks after respiratory
infection or diarrhoea (particularly Campylobacter).

In Europe and North America, acute inflammatory neuropathy is most commonly
demyelinating ( AIDP ).

Axonal variants ,either ( AMAN ) or (ASMAN) are more common in China and Japan .

Clinical features:

Distal paraesthesia and limb pains precede a rapidly ascending muscle weakness from lower
to upper limbs , more marked proximally than distally.

Facial and bulbar weakness commonly develops , and respiratory weakness requiring
ventilatory support occurs in 20 % of cases .

In most patients weakness progresses for 1-3 weeks but rapid deterioration to respiratory
failure can develop within hours

On examination there is diffuse weakness with widespread loss of reflexes.

An unusual axonal variant described by Miller Fisher comprises the triad of ophthalmoplegia
, ataxia and areflexia .

Overall, 80% of patients recover completely within 3-6 months, 4% die, and the remainder
suffer residual neurological disability which can be severe. Adverse prognostic features
include older age, rapid deterioration to ventilation and evidence of axonal loss on EMG.

Investigations:

The CSF protein is abnormal at some stage of the illness, but may be normal in the first 10
days. There is usually no rise in CSF cells ( lymphocytosis of > 50/ml suggests an alternative
diagnosis ).

Electrophysiological studies are often normal in the early stages but show typical changes
after a week or so , with conduction block and multifocal motor slowing , sometimes most
evident proximally as delayed F-waves.

Management:

During the phase of deterioration , regular monitoring of respiratory function ( vital capacity
and arterial blood gases) is required, as respiratory failure may develop with little warning
and require ventilatory support.

Ventilation may be needed if the vital capacity falls below 1L , but ventilation is more often
required because of bulbar weakness leading to aspiration.

General management to protect the airway and prevent pressure sores and venous thrombosis
is essential .

Corticosteroids have been shown to be ineffective .

Plasma exchange and intravenous immunoglobulin therapy shorten the duration of the illness
,reduce severity and improve prognosis provided treatment is started within 14 days of the
onset of symptoms .

Chronic demyelinating polyneuropathy لالطالع

It is either hereditary or immune-mediated.

Charcot-Marie-Tooth (CMT) disease which is of many types ;the most commom 70-80 % is
the autosomal dominant one causing distal wasting (inverted champagne bottle or stork leg )
often with pes cavus and a predominantely motor involvement

Presents with a relapsing or progressive generalized neuropathy.

Sensory,motor or autonomic nerves can be involved but the signs are predominantely motor .

Multifocal Motor Neuropathy MMN is a variant with motor involvement only .

CIDP لالطالع

CIDP usually responds to immunosuppressive treatment ;corticosteroids , methotrexate or
cyclophosphamide OR to immunomodulatory treatments (plasma exchange or IVIg ),which
is the best of patients with MMN .

About 10 % of patients with acquired demyelinating polyneuropathy have an abnormal
serum paraprotein , sometimes associated with a lymphoproliferative malignancy .

DIABETIC NEUROPATHY:

 AMYOTROPHY = PAIN &WEAKNESS WITH ATROPHY PELVIC GIRDLE

&THIGH MUSCLES WITH ABSENT KNEE REFLEX &LITTLE SENSORY LOSS

 MONONEUROPATHY = ACUTE PAINFUL CRANIAL NERVES
 BOTH HAVE GOOD PROGNOSIS

Entrapment neuropathy:

Focal compression or entrapment is the usual cause of mononeuropathy . However , some
patients present with what initially appears to be a single nerve lesion and then go on to
develop multiple nerve lesions.This is termed mononeuritis multiplex .

Symptoms and signs:

In an entrapment neuropathy, pressure initially damages the myelin sheath, and
neurophysiology will show slowing of conduction over the relevant site. Sustained or severe
pressure damages the integrity of the axons, demonstrable as loss of the sensory action
potential distal to the site of compression.

Certain conditions increase the propensity to develop entrapment neuropathies. These
include acromegaly, hypothyroidism, pregnancy, any pre-existing mild generalised axonal
neuropathy (e.g. diabetes), and oseophytes. Patients with multiple recurrent entrapment
neuropathies, especially at unusual sites, should be screened for autosomal dominant
hereditary neuropathy with liability to pressure palsies (HNPP) .

Unless axonal loss has occurred, entrapment neuropathies will recover, provided the pressure
on the nerve is relieved, either by avoiding precipitating activities or limb positions, or by
surgical decompression.

Entrapment neuropathy CTS:

 MEDIAN N. COMPRESSION AT THE WRIST
 IDIOPATHIC, PREGNANCY, TRAUMA, ARTHRITIS, MYXOEDEMA,

ACROMEGALY, TENOSYNOVITIS……

 PAIN, NUMBNESS IN MEDIAN N. DISTIBUTION ?SHOULDER

 AT NIGHT

  WEAKNESS & ATROPHY OF THENAR MUSCLES
  TINEL SIGN , PHALEN MANEUVER
  Rx LOCAL STEROIDS, WRIST SPLINT,   SURGERY

Facial nerve palsy:

Idiopathic facial nerve palsy or Bells palsy is a common condition affecting all ages and both
sexes .The lesion is within the facial canal and may be due to reactivation of latent herpes
simplex virus 1 infection .Symptoms usually develop subacutely over a few hours , with pain
around the ear preceding the unilateral facial weakness. Patients often describe the face as
numb but there is no objective sensory loss (except possibly to taste).

Hyperacusis can occur if the nerve to stapedius is involved , and there may be diminished
salivation and tear secretion . Examination reveals an ipsilateral lower motor neuron facial
nerve palsy . Vesicles in the ear or on the palate indicate that the facial palsyis due to herpes
zoster rather than Bells palsy .

Prednisolone 40-60 mg daily for a week speeds recovery if started within 72 hours.Artificial
tears and ointment prevent exposure keratitis and the eye should be taped shut overnight.
About 80% of patients recover spontaneously within 12 weeks. A slow or poor recovery is
predicted by complete paralysis, older age and reduced facial motor action potential
amplitude after the first week. Recurrences can occur but should prompt further
investigation. Aberrant re-innervation may occur during recovery, producing unwanted facial
movements (e.g. eye closure when the mouth is moved) or 'crocodile tears' (tearing during
salivation).

MOTOR NEURONE DISEASE:

 DEGENERATION OF MOTOR NEURONS IN SPINAL CORD MOTOR

NUCLIE OF LOWER CRANIAL NERVES ,

  ONSET 30 -60 YEARS, > IN MALES, 2/ 100000,
  SPORADIC, 5- 10 %FAMILIAL ( AUT. DOM. ) CHR 15
  CAUSE : UNKNOWN

o  ?AUTOIMMUNE
o  INCREASED OFR FORMATION
o  REDUCED NEUROTROPHIC FACTORS
o  EXCITOTOXINS

CLINICAL TYPES &FEATURES

A. PROGRESSIVE BULBAR PALSY = LMN CRANIAL NERVES
B.PSEUDOBULBAR PALSY = UMN CRANIAL NERVES
C.SPINAL MUSCULAR ATROPHY = LMN SPINAL CORD AHC
D. PURE LATERAL SCLEROSIS = UMN IN LIMBS
E. AMYOTROPHIC LAT. SCLEROSIS = MIXED C. & D.
MAY BE WITH A. & B.

NO EXTRA OCULAR MUSCLES INVOLVEMENT
NO SPHINCTER INVOLVEMENT
NO SENSORY DEFICIT
NORMAL CSF
EMG

Rx = RILUZOLE 100mg /day may slow progression & reduce mortality. It is GLUTAMATE
ANTAGONIST . Side effects = fatigue, dizziness, GIT diturbance, raised liver enzymes.
Anticholinergics for drolling of saliva
Physiotherapy
FEEDING = Semisolid diet, NG tube, Gastrostomy.
Tracheostomy

Prognosis = Bad especially in Bulbar type
Progressive &fatal in 3 -5 years

MND IN CHILDREN

لالطالع

 INFANTILE = WERDING HOFFMANN DIS. ONSET AT 3 MONTHS , DEATH

  AT 3 YEARS, AR , DIFFICULT SUCKING , SWALLOWING&
  VENTILATION, ATROPHY & FASCICULATION OF TONGUE &
  LHMB MUSCLES, NO SENSORY DEFICIT , NO Rx

 INTERMEDIATE = CHRONIC W-H-DISEASE

 AR, 2

of 1

year, LESS BULBAR INVOLVEMENT ,

 BENIGN, SLOWLY PROGRESSIVE , KYPHOSCOLIOSIS

 &CONTRACTURES , SURVIVE TO ADULTHOOD

 JUVENILE = KUGELBERG – WELANDER DISEASE

  AR, COULD BE  AD OR X – LINKED
  ONSET AT CHILDHOOD OR EARLY ADOLESCENCE
  MORE IN PROXIMAL MUSCLES , LITTLE BULBAR INVOLV.
  DISABILITY IN EARLY ADULT LIFE
  NO Rx

SYRINGOMYELIA

لالطالع

  CAVITATION OF SPINAL CORD
  COMMUNICATING = CENTRAL CANAL &THE CAVITY
  NON – COMMUN.   = CYSTIC DILATATION OF SPINAL CORD
  CLINICALLY = DISSOCIATED SENSORY LOSS

  WEAK. & WASTING OF MUSCLES ; CERVICAL &T 1
  PYRAMIDAL SIGNS &SPHINCTER DIST. BELOW
  NECK & RADICULAR PAIN
  HORNER SYNDROME
  SYRINGOBULBIA

 MAY BE ASSO. WITH TUMOR, TRAUMA , ARACHNOIDITIS OR ANMALIES LIKE

ARNOLD – CHIARI MALFORMATION

 Rx = DECOMPRESSION OF DISTENDED SYRINX

SUBACUTE COMBINED DEGEN. OF THE CORD

لالطالع

  B12 DEFICIENCY
  PARASTHESIA &WEAKNESS OF THE EXTREMITIES = PERIPHERAL NERVES
  SPASTIC PARAPARESIS = PYRAMIDAL FIBERS
  SENSORY ATAXIA  = POSTERIOR COLUMN TRACT
  LHERMITTS SIGN
  SCOTOMAS = OPTIC ATROPHY
  BEHAVIOURAL OR PSYCHIATRIC SYMPTOMS
  ANEMIA MEGALOPLASTIC NOT NECESSARILY PRESENT
  Rx   B12I. M. …….