37.2 Specialty I: Neurosurgery (Raised Intracranial Pressure and Herniation, Head Injury and Hematomas, Spontaneous Intracranial Hemorrhage, CNS and Peripheral Nerve Tumors, Spinal Cord Compression, Neurosurgical Infections) and Ophthalmology (Glaucoma, Cataract, Ophthalmic Emergencies)

Why this area matters

Head injury from motorcycle crashes is a major cause of death and disability in the Philippines. Stroke from hypertensive hemorrhage is common, and CNS infections (TB meningitis, brain abscess) still cause neurosurgical emergencies. Cataract is the leading cause of blindness in the country. Questions test emergency recognition and first steps.

Raised intracranial pressure and herniation

• Monro-Kellie doctrine: the skull contains brain, blood and CSF at a fixed total volume. An expanding lesion is compensated at first by displacing CSF and venous blood, then ICP rises steeply.
• Cerebral perfusion pressure (CPP) equals MAP minus ICP. A target of about 60 to 70 mmHg is used in TBI.
• Signs:
  • headache worse in the morning and when lying down;
  • vomiting;
  • papilledema;
  • falling level of consciousness;
  • sixth nerve palsy (a false localizing sign);
  • in infants, a bulging fontanel and increasing head size.
• Herniation syndromes:
  • uncal (transtentorial) herniation: an ipsilateral fixed dilated pupil (CN III compression), contralateral hemiparesis, then coma;
  • tonsillar herniation: compresses the medulla, causing respiratory arrest;
  • Cushing triad: hypertension, bradycardia and irregular respiration.
• Emergency management:
  • airway and ventilation (avoid hypoxia and hypercarbia);
  • head elevation 30 degrees with the neck straight;
  • osmotherapy with mannitol or hypertonic saline;
  • brief hyperventilation only as a bridge to surgery;
  • sedation;
  • treat fever and seizures;
  • surgical decompression (evacuate the lesion, external ventricular drain, decompressive craniectomy).
  • Steroids reduce edema around tumors, but not in trauma or stroke.

Head injury and its hematomas

• Classification: severity is graded by the GCS (mild 13 to 15, moderate 9 to 12, severe 3 to 8).
• Primary versus secondary injury:
  • primary injury happens at impact;
  • secondary injury comes from hypoxia, hypotension, raised ICP, seizures, fever and hypoglycemia, and is preventable;
  • a single episode of hypotension (systolic below 90) or hypoxia significantly worsens outcome.
• CT of the head is indicated by clinical decision rules (GCS below 15 at 2 hours, suspected skull fracture, vomiting, age 65 or more, dangerous mechanism, anticoagulant use).
• Skull fractures:
  • depressed fractures deeper than the skull thickness or open fractures need elevation and debridement;
  • basal skull fracture: raccoon eyes, Battle sign (mastoid bruising), CSF rhinorrhea or otorrhea and hemotympanum; do not pass a nasal tube.
• Diffuse axonal injury: coma out of proportion to CT findings, from rotational acceleration.
• Chronic subdural hematoma: occurs in elderly people and alcoholics on antithrombotics. It presents over weeks with confusion, headache and hemiparesis, and is drained by burr holes.

Operative and ICU management of head injury:

• Acute epidural hematoma (lens-shaped on CT, often with a temporal fracture over the middle meningeal artery): evacuate urgently if over about 30 mL, or with midline shift, a falling GCS or pupillary signs.
• Acute subdural hematoma (crescent-shaped, from torn bridging veins, usually with underlying brain injury): evacuate if thicker than about 10 mm, with midline shift over 5 mm, or if GCS falls. The outcome is worse than for epidural hematoma.
• Severe TBI (GCS 8 or less):
  • intubate to protect the airway;
  • keep oxygen saturation normal and systolic BP at or above 100 to 110 mmHg;
  • monitor ICP and treat ICP above about 22 mmHg;
  • prophylactic antiseizure drugs for the first 7 days reduce early seizures;
  • steroids are not used, because they increase mortality in head injury;
  • decompressive craniectomy for refractory ICP.
• The GCS table and the full hematoma features are in the trauma section.

Spontaneous intracranial hemorrhage

• Subarachnoid hemorrhage:
  • usually a ruptured berry aneurysm (circle of Willis, especially the anterior communicating artery);
  • a thunderclap headache ("worst ever"), neck stiffness, vomiting and loss of consciousness;
  • non-contrast CT first, and lumbar puncture for xanthochromia if CT is negative after 6 hours;
  • CT angiography locates the aneurysm;
  • the aneurysm is secured early by endovascular coiling or surgical clipping;
  • nimodipine prevents delayed cerebral ischemia from vasospasm (days 4 to 14);
  • watch for hydrocephalus, rebleeding and hyponatremia.
• Hypertensive intracerebral hemorrhage:
  • sites are the basal ganglia (putamen), thalamus, pons and cerebellum;
  • manage with BP control, reversal of anticoagulation and ICP management;
  • cerebellar hemorrhage over 3 cm or with brainstem compression or hydrocephalus needs urgent surgical evacuation.
• Arteriovenous malformations cause hemorrhage and seizures in young people.

CNS and peripheral nerve tumors

• Adult brain tumors:
  • metastases are the most common (lung, breast, melanoma, kidney, colon), often multiple at the gray-white junction;
  • glioblastoma is the most common primary malignant tumor: a ring-enhancing mass crossing the corpus callosum ("butterfly"), treated with resection, radiotherapy and temozolomide, with a poor prognosis;
  • meningioma is extra-axial, dural-based with a dural tail, usually benign, and resected if symptomatic;
  • pituitary adenoma causes bitemporal hemianopia and hormonal syndromes, and is treated transsphenoidally (prolactinomas with dopamine agonists);
  • vestibular schwannoma arises at the cerebellopontine angle.
• Pediatric brain tumors: most are infratentorial (medulloblastoma, pilocytic astrocytoma, ependymoma), plus craniopharyngioma.
• Presentation of brain tumors: progressive focal deficits, seizures, raised ICP and personality change. Dexamethasone reduces edema.
• Spinal tumors: extradural metastases are the most common; meningiomas and schwannomas are intradural extramedullary.
• Peripheral nerve tumors: schwannoma (benign, can be shelled out from the nerve) and neurofibroma (part of NF1, which can become a malignant peripheral nerve sheath tumor).
• Peripheral nerve injury:
  • neurapraxia recovers fully;
  • axonotmesis recovers slowly by regeneration;
  • neurotmesis (a severed nerve) needs repair.

Spinal emergencies

• Malignant spinal cord compression:
  • back pain (often at night), then weakness, sensory level and sphincter dysfunction in a cancer patient;
  • urgent MRI of the whole spine;
  • high-dose dexamethasone;
  • radiotherapy and/or surgical decompression.
• Cauda equina syndrome:
  • from a large central disc herniation, tumor or abscess;
  • saddle anesthesia, urinary retention with overflow, fecal incontinence and bilateral sciatica and weakness;
  • emergency MRI and surgical decompression within 48 hours preserve function.
• Spinal epidural abscess:
  • fever, back pain and neurologic deficit;
  • often S. aureus in diabetics or people who inject drugs;
  • MRI, antibiotics and decompression.
• Spinal TB (Pott disease) is treated with anti-TB drugs, with surgery for deformity or cord compression.

Neurosurgical infections

• Brain abscess:
  • spreads from the sinuses, ears and teeth, or by blood (endocarditis, cyanotic heart disease);
  • headache, fever (not always) and focal signs;
  • ring-enhancing lesion on imaging;
  • treated with aspiration or excision plus antibiotics for 6 to 8 weeks (ceftriaxone, metronidazole and vancomycin as indicated).
• Subdural empyema is a surgical emergency.
• Ventriculoperitoneal shunt infection occurs mainly in the first months, usually from skin staphylococci. Remove the shunt, place an external drain and give antibiotics.
• Shunt malfunction presents with signs of raised ICP.
• Neurocysticercosis and tuberculomas are treated medically, with surgery for hydrocephalus or mass effect.

Ophthalmology

• Primary open-angle glaucoma:
  • painless, gradual peripheral (tunnel) vision loss with increased cup-to-disc ratio and raised or normal IOP;
  • risk factors are age, family history, myopia and diabetes;
  • treated with prostaglandin analog drops (latanoprost), beta-blockers, alpha-agonists or carbonic anhydrase inhibitors, laser trabeculoplasty or trabeculectomy;
  • vision lost is not recovered, so screening matters.
• Acute angle-closure glaucoma (a painful red eye with a mid-dilated pupil) is covered in the red-eye section below.
• Cataract:
  • lens opacity causing gradual painless blurring and glare;
  • causes are age (most common), diabetes, steroids, trauma, UV light, congenital rubella and galactosemia;
  • treated by cataract surgery (phacoemulsification or small-incision surgery with an intraocular lens) when vision limits daily life;
  • congenital cataracts (absent red reflex) need early surgery to prevent amblyopia.

Ophthalmology and Otolaryngology (ENT) Emergencies

Acute Angle-Closure Glaucoma (AACG)

Obstruction of aqueous humor outflow through the trabecular meshwork by apposition of the peripheral iris, triggered by pupillary dilation (mydriasis in dark environments, anticholinergics, sympathomimetics).

• Clinical Presentation: Sudden, excruciating unilateral ocular and peri-orbital pain, frontotemporal headache, severe nausea and vomiting, blurred vision, and seeing rainbow-colored halos around lights.
• Physical Examination: Diffuse conjunctival injection ("ciliary flush"), hazy/steamy cornea, shallow anterior chamber, fixed mid-dilated non-reactive pupil, and a stony-hard globe on gentle digital palpation. Intraocular pressure (IOP) is markedly elevated ($> 40-70\text{ mmHg}$; normal: $10-21\text{ mmHg}$).
• Immediate Medical Management: Lower IOP rapidly using multi-agent pharmacotherapy:
  • Topical $\beta$-blocker (Timolol 0.5%; decreases aqueous production).
  • Topical $\alpha_2$-adrenergic agonist (Apraclonidine 1%; decreases production and increases outflow).
  • Carbonic anhydrase inhibitor (Acetazolamide $500\text{ mg}$ IV or oral; suppresses aqueous humor formation).
  • Osmotic agent (IV Mannitol $1-2\text{ g/kg}$; rapidly reduces vitreous volume in refractory cases).
  • Topical miotic (Pilocarpine 1-2%; applied once IOP $< 40\text{ mmHg}$ to induce pupillary constriction, pulling the peripheral iris away from the trabecular meshwork).
• Definitive Treatment: Bilateral Peripheral Laser Iridotomy (relieves pupillary block and treats contralateral eye prophylactically).

Retinal Detachment

Separation of the neurosensory retina from the underlying retinal pigment epithelium, most commonly rhegmatogenous (retinal tear allows liquid vitreous into subretinal space). Risk factors: severe myopia, prior cataract surgery, ocular trauma.

• Clinical Presentation: Painless vision loss preceded by photopsia (flashes of light), sudden shower of floaters ("cobwebs" or "soot"), followed by a dark shadow or "curtain falling over the visual field".
• Fundoscopy: Elevation of wrinkled, grayish, mobile, undulating retina with loss of the underlying choroidal vascular pattern. Urgent operative reattachment (pneumatic retinopexy, scleral buckling, or vitrectomy) is mandatory to prevent permanent macular ischemia.

Other eye emergencies:

• Chemical injury:
  • irrigate immediately and copiously (litres of saline or water, at least 30 minutes) before testing acuity or referral, until the pH is neutral;
  • alkali burns are worst.
• Central retinal artery occlusion: sudden painless monocular vision loss, a pale retina with a cherry-red spot. Look for an embolic source or giant cell arteritis (check ESR and give steroids if suspected).
• Penetrating eye injury: shield the eye, do not press on it or remove a protruding object, give antibiotics and tetanus prophylaxis, and refer urgently.
• Orbital (postseptal) cellulitis: proptosis, painful and restricted eye movements and reduced vision. Needs IV antibiotics and CT.
• Hyphema: bed rest with the head raised, a shield, and monitoring of IOP.
• Corneal ulcer in contact lens wearers: Pseudomonas; needs urgent ophthalmology review.