Dr. S. Rajkumar
Brain & Spine Surgeon, KG Hospital, Coimbatore — with Dr. T.C.R. Ramakrishnan and Dr. R. Senthilkumar.
Arnold–Chiari Malformation (Chiari Malformation) is a structural disorder affecting the posterior fossa and hindbrain — the region that includes the cerebellum, pons, and medulla oblongata. This condition disrupts the normal flow of cerebrospinal fluid (CSF) and can cause the cerebellar tonsils to herniate through the foramen magnum, the natural opening at the skull base.
Depending on severity, associated abnormalities such as hydrocephalus, syringomyelia, syringobulbia, and spinal dysraphism may occur. Among the various types, Chiari Type I Malformation is the most common and mildest form, often discovered incidentally during MRI scans, identified when the cerebellar tonsils extend more than 5 mm below the foramen magnum.
Case Reports: Successful Chiari Malformation Surgeries at KG Hospital
Case 1
A 32-year-old female presented with hoarseness of voice, difficulty swallowing, occipital headache, and neck pain. Clinical findings included right 6th nerve palsy, reduced gag reflex, and right 12th nerve palsy. MRI confirmed Chiari malformation with syringobulbia. She underwent Foramen Magnum Decompression (FMD) with arachnoid band excision, tonsillar cauterization, and lax duraplasty using fascia lata. Post-surgery, swallowing difficulty and voice quality improved remarkably within days.
Case 2
A 23-year-old male reported neck pain, paresthesia over the right shoulder, and sleep-related breathing difficulty, with dissociated sensory loss and wasting of the right deltoid muscle on examination. MRI showed cerebellar tonsillar descent with extensive syringomyelia (C2–D2). He underwent Foramen Magnum Decompression, tonsillar cauterization, and lax duraplasty, experiencing marked symptom relief and continued recovery during follow-up.
Symptoms
The most common symptom is a suboccipital headache and neck pain that worsens with coughing, sneezing, or straining. Other symptoms include dizziness or vertigo, blurred or double vision, difficulty swallowing or speaking, weakness or numbness in limbs, dissociated sensory loss, gait imbalance or ataxia, and sleep apnea due to brainstem compression.
Diagnostic Evaluation
MRI of the brain and cervical spine is the gold standard for diagnosis, identifying descent of the cerebellar tonsils (>5 mm), reduced posterior fossa space, and presence of syringomyelia or syringobulbia. Cine MRI can further evaluate CSF flow dynamics to guide treatment planning.
Surgical Treatment: Posterior Fossa Decompression (PFD)
- Suboccipital craniectomy — removes bone to enlarge the foramen magnum
- C1 (and sometimes C2) laminectomy — decompresses the brainstem
- Dural opening to inspect and expand space
- Dissection of arachnoid adhesions to improve CSF circulation
- Duraplasty — enlargement using fascia lata or synthetic graft
- Tonsillar cauterization, if required, to reduce herniation
Early surgical intervention — within two years of symptom onset — is associated with the best neurological recovery. With timely diagnosis, Chiari I Malformation has an excellent prognosis.
