8 Other Diseases



10.1055/b-0039-171770

8 Other Diseases



8.1 Hydrocephalus (Table 8.1)



















































Definition/condition

Diagnosis and comments

Treatment

Imaging criteria for diagnosis of hydrocephalus


Hydrocephalus suspected if:




  1. Ballooning of lateral ventricles and 3rd ventricle



  2. Transependymal CSF (hypodense on CT, hyperintense on T2WI MRI)



  3. Frontal horn (FH)/internal diameter (ID) ratio > 0.5



  4. FH/biparietal diameter (BPD; Evan’s ratio) > 0.3



  5. Temporal tip diameter > 2 mm


  1. Nonsurgical management of hydrocephalus:




    • Useful for premature newborns with low birth weights



    • Temporizing measures




      1. Serial spinal or ventricular taps



      2. Acetazolamide + steroids



  2. Surgical management of hydrocephalus




    1. Ventriculoperitoneal shunt:




      • Indications: communicating / NPH AND noncommunicating hydrocephalus



      • Ventricular catheter entry point: see Table 8.2



      • Peritoneal catheter:




        1. Midline—between rectus abdominis muscles



        2. Subcostal: 3 cm below ribcage in mammillary line



      • Alternative locations for distal shunt catheter (if peritoneum is contraindicated):




        1. Right atrium or superior vena cava



        2. Pleural cavity



        3. Gallbladder



        4. Ureter or bladder



        5. Sagittal sinus



    2. Endoscopic third ventriculostomy:




      • Indications: Recommended for obstructive hydrocephalus (especially aqueductal stenosis)



      • There are reports of successful treatment of communicating hydrocephalus although mechanism poorly understood



      • Requires very thin (transparent) floor of the 3rd ventricle



      • Approach with rigid endoscope through frontal horn into foramen of Monro into the 3rd ventricle



      • Direct endoscopic visualization of mammillary bodies and tip of basilar artery through the 3rd ventricular ependyma MANDATORY—if not visualized, abort the procedure



    3. Lumboperitoneal shunt




      • Indications: communicating hydrocephalus / NPH ONLY



      • Placement of lumbar catheter with C-arm guidance



      • To reduce valve migration or difficulty tapping shunt → Place valve over iliac bone just below crest


      To reduce risk of overshunting → Place programmable shunt valve


Obstructive Hydrocephalus (AKA Noncommunicating Hydrocephalus)


Obstruction of the normal CSF flow pathways at:




  1. Foramen of Monro (colloid cyst, etc.)



  2. Cerebral aqueduct (aqueductal stenosis, tectal glioma, etc.)



  3. Foramen magnum (Chiari’s malformation. Dandy–Walker malformation, etc.)



  4. Trapped ventricle (see below)


Communicating Hydrocephalus




  1. Inadequate absorption of CSF because of “plugged” arachnoid granulations:




    • Posthemorrhage



    • Postinfection



    • Tumor



    • Arteriovenous malformation (AVM)



    • Postsurgery



  2. Overproduction of CSF:




    • Very rare



    • Typically related to choroid plexus papilloma


Normal-pressure hydrocephalus (NPH)




  • A type of communicating hydrocephalus



  • Cause: unknown



  • Presentation with typical triad of symptoms:




    1. Gait disturbance (small steps, difficulty turning)



    2. Urinary incontinence



    3. Memory impairment



  • Diagnosis:




    1. Clinical presentation PLUS MRI brain consistent with hydrocephalus



    2. If diagnosis likely or probable, perform ancillary test:




      1. Lumbar puncture: opening pressure >10 cm H2O is a positive predictor of good outcome after shunt (opening pressure >24 cm H2O is not consistent with NPH but indicative of obstructive hydrocephalus)



      2. Large-volume CSF removal: spinal tap → remove 40–50 mL → then check for improvement in symptoms



      3. Continuous CSF drainage: place lumbar drainage → remove 10 mL/h for 3 – 5 d → then check for improvement in symptoms



  • Improvement after treatment (best response first):




    1. Incontinence



    2. Gait



    3. Memory


Arrested Hydrocephalus (AKA Compensated Hydrocephalus)


Three criteria:




  1. Near-normal ventricular size



  2. Normal head growth



  3. Normal development


  • Spontaneous third ventriculostomy has been suggested



  • Close clinical follow-up for signs of high intracranial pressure (ICP)


Trapped ventricle




  • Can occur in ventricles containing choroid plexus (ALL but frontal and occipital horns)



  • Outflow of ventricle is obstructed, but CSF production continues



  • For the 4th ventricle: inflow into the 4th ventricle AND outflow (foramina Luschka and Magendie) are obstructed



  • Typically seen postinfection (4th ventricle) or with tumors (all others)


  • Remove cause of obstruction (i.e., tumor)



  • Implant separate shunt for trapped ventricle


External Hydrocephalus




  • Large subarachnoid space (bifrontal) and wide interhemispheric fissure (frontally) in infants



  • Ventricles are mildly dilated or normal



  • Head perimeter crosses percentiles



  • Possibly frontal bossing



  • Look for “cortical vein sign” (veins extend from inner skull to cortical surface, which is not to be seen in subdural hematoma)


  • Close follow-up



  • Self-resolving by 2–3 y of age


Siphoning




  • Patient with shunt has orthostatic headache



  • Possibly slit ventricles



  • Possible subdural hematomas


  • Anti-siphon device OR



  • Increase programmable valve pressure


Slit Ventricle Syndrome




  • Slit ventricles on imaging studies AND



  • Signs of intermittent or constant shunt malfunction



  • Causes:




    1. Permanent scarred down ventricles



    2. Intermittent ventricular collapse that temporarily occludes the catheter


  • Always rule out shunt malfunction first, because ventricles may just be scarred down slit



  • Steroids may help



  • Increase valve pressure setting


Shunt malfunction in pregnancy





  • In trimesters 1 and 2: new ventriculoperitoneal shunt



  • In trimester 3: new ventriculoatrial or ventriculopleural shunt



  • Prophylactic antibiotics in labor and continue until 48 h after birth (Ampicillin 2 g IV every 4 h + Gentamicin 1.5 mg/kg IV every 8 h)



8.2 Ventricular Catheter Placement Tips (Table 8.2)


























Entry point

Specifics

Kocher’s point


Coordinates:




  • 11 cm up from nasion (= 1 cm anterior from coronal suture) on midline



  • 3 cm lateral of midline (midpupillary line)


Trajectory:




  • Aim toward ipsilateral medial canthus (ipsilateral eye) and external acoustic meatus



  • Length: NOT DEEPER than 6.5 cm from the skull


It is the Preferred entry point for ventricular access


Frazier’s point


Coordinates:




  • 7 cm up from inion on midline



  • 3 cm lateral


Trajectory:




  • Aim toward nasion



  • Length: 10 cm


For emergency access, if needed during posterior fossa craniotomy


Keen’s point


Coordinates:




  • 3 cm above and



  • 3 cm posterior to pinna


Trajectory:




  • Aim toward nasion



  • Length: 7–10 cm


Dandy’s point


Coordinates:




  • 3 cm up from inion on midline



  • 2 cm lateral to inion


Beware of transverse sinus


Trajectory:




  • Aim toward nasion



  • Length: 7 cm


Remember:




  1. Conversion from cm H2O to mm Hg:




    • Multiply pressure in cm H2O × 0.74



    • 10 cm H2O = 7.4 mm Hg



  2. Conversion from mm Hg to cm H2O:




    • Multiply pressure in mm Hg × 1.36



    • 10 mm Hg = 13.6 cm H2O



8.3 Intracranial Hypotension and Hypertension (Table 8.3 )


























Clinical presentation

Diagnostic studies

Treatment



  1. Spontaneous intracerebral hypotension




  • Spontaneous positional (orthostatic) headache



  • No history of trauma or iatrogenic cause


REMEMBER:


Spontaneous subdural hemorrhage (without trauma): search for spine CSF leak


  1. Spinal tap: Low CSF pressure (<6 cm H2O) (not always)



  2. MRI brain and spine with contrast:




    • Pachymeningeal enhancement



    • Sagging brain



    • Pituitary hyperemia



    • Subdural collections



    • Engorged veins



  3. CT brain (coronal thin cuts) and spine with intrathecal contrast with immediate (45 min) and delayed (4 h) images:




    • Skull base leaks



    • Spinal meningeal cysts


Delayed diagnosis makes treatment more difficult


  1. Symptomatic treatment:




    • Treat like postlumbar puncture headache:




      • Bed rest



      • Hydration



      • Caffeine



    • Epidural blood patch that can be repeated (inject 10–20 mL of autologous blood in epidural space and place the patient placed in Trendelenburg after the injection)



  2. Surgical repair (exact site of leak must be known)




  • B. Pseudotumor cerebri AKA benign (or idiopathic) intracranial hypertension




  • Most common in (4 F’s):




    • Female



    • Fat



    • Fertile



    • Forty (usually 40 y old)



  • Common symptoms:




    • Headache



    • Papilledema



    • Enlarged blind spot



    • Constricted visual field (the best test for following vision)



    • Blindness may occur but rarely



  • Uncommon symptoms:




    • CMVI palsy



    • Tinnitus



    • Nausea



    • Neck stiffness


  1. MRV brain: exclude venous sinus thrombosis or stenosis



  2. MRI brain




    • Slit ventricles



    • Possible empty sella



  3. Lumbar puncture: CSF pressure > 20 cm H2O (remember the possible variations during day; so if there is strong suspicion, repeat the test)


  1. General treatment recommendations:




    • Weight loss (recent gain can worsen vision)



    • Salt restriction



    • Diuretics (acetazolamide, furosemide)



    • Topiramate



    • Steroids (short term if no response to other medications)



    • Serial lumbar punctures (consider especially in pregnancy)



  2. Surgery:




    1. Headache ± visual disturbance:




      • Ventricular peritoneal shunt



      • Lumbar peritoneal shunt



      • Always consider programmable shunt systems



    2. Visual disturbance without headache:




      • Shunt



      • Optic fenestration


REMEMBER: Spontaneous remission, but also relapse, is common. Close follow-up necessary.



8.4 Arachnoid Cyst (Table 8.4 )


















Epidemiology/classification

Histology/Presentation/diagnostics

Treatment

Arachnoid cyst AKA leptomeningeal cyst (CAUTION: not synonymous with posttraumatic leptomeningeal cyst; see Pediatric Head Injury in Chapter 6)


Location:




  • Middle cranial fossa (the most common)



  • Cerebellopontine angle



  • Suprasellar area



  • Posterior fossa



  • Intraventricular



  • Optic nerve



  • Spine (most commonly thoracic spine)


Male:female = 3:1


Galassi classification of the middle cranial fossa arachnoid cysts:




  1. Type 1:




    • Small, temporal tip



    • Free communication with cisterns



  2. Type 2:




    • Intermediate size



    • Rectangular shape



    • It originally communicated with subarachnoid space and later sealed off



  3. Type 3:




    • Large



    • No communication to subarachnoid space



    • Causing local mass effect

Proposed mechanisms:




  • Cyst formation and brain hypoplasia secondary to cyst development



  • Primary brain hypoplasia of brain (i.e., temporal lobe) with arachnoid cyst “filling the void”


Histology:




  • Splitting of arachnoid membrane



  • Thickening of the collagen layer in cyst wall



  • No arachnoid trabeculations within the cyst



  • Hyperplastic arachnoid cells in cyst wall


Clinical presentation:




  • Commonly an incidental finding



  • Macrocephaly



  • Asymmetric head growth with focal skull protrusion



  • Seizures (controversial)



  • Signs of increased ICP



  • Pituitary dysfunction (suprasellar cysts)



  • Hydrocephalus (suprasellar cysts)



  • Visual impairment (optic nerve cyst)


Diagnostic tests:




  • CT and MRI



  • Follows CSF intensity on all MRI sequences (difference from dermoid cysts)


  1. Asymptomatic:



  2. Repeat MRI imaging at 6 mo



  3. If no change in size or appearance, no further imaging studies are needed



  4. Symptomatic:



  5. Craniotomy with cyst fenestration and opening cyst to subarachnoid space



  6. Endoscopic cyst fenestration and cyst wall marsupialization



  7. Cystoperitoneal shunt



  8. CT-guided needle aspiration (spinal arachnoid cysts)



  9. Cyst amputation at the stalk (spinal arachnoid cysts)


REMEMBER:


Cysts are a known RISK FACTOR for development of subdural hematomas . Patients need to be counseled regarding contact sports and head trauma

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May 11, 2020 | Posted by in NEUROSURGERY | Comments Off on 8 Other Diseases

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