Differential Diagnosis

The patient's symptoms have been ongoing for over 20 days, with a complex presentation of headache, balance problems, visual disturbances, speech difficulties, and widespread pain. Considering the patient's known conditions, including Chiari malformation and idiopathic intracranial hypertension, the following differential diagnoses are proposed:

• Single Most Likely Diagnosis
  • Chronic Daily Headache with features of New Daily Persistent Headache (NDPH) or Hemicrania Continua: The patient's headache has been continuous for over 20 days, with a consistent pattern of pain on one side of the head, face, and neck, and occasional shifts to the other side. The presence of autonomic features like photophobia and the pattern of pain suggest a primary headache disorder, but the chronic nature and associated symptoms like balance problems and visual disturbances complicate the picture.
• Other Likely Diagnoses
  • Complications of Chiari Malformation: Given the patient's known Chiari malformation, complications such as syringomyelia (formation of a fluid-filled cavity within the spinal cord) or cerebellar tonsil herniation could explain some of the symptoms, including balance problems, pain, and potentially some of the neurological deficits.
  • Idiopathic Intracranial Hypertension (IIH) Exacerbation: The patient's history of IIH, combined with symptoms like visual disturbances (blurring and lines across vision), headache, and photophobia, suggests that an exacerbation of IIH could be contributing to the current clinical picture.
  • Cervicogenic Headache: The patient's pain pattern, involving the neck, shoulder, and head on one side, could suggest a cervicogenic headache, where the pain is referred from the cervical spine.
• Do Not Miss Diagnoses
  • Brain Tumor or Mass Lesion: Although less likely, given the duration and nature of symptoms, a brain tumor or other mass lesion could cause increased intracranial pressure, leading to headache, visual disturbances, and neurological deficits. The presence of a Chiari malformation and history of lumbar punctures complicates the clinical picture but does not rule out this possibility.
  • Stroke or Transient Ischemic Attack (TIA): The patient's symptoms of sudden onset of speech difficulties, balance problems, and visual disturbances could suggest a vascular event, although the chronic nature of most symptoms makes this less likely.
  • Multiple Sclerosis (MS): MS could explain some of the neurological symptoms, including vision problems, balance issues, and widespread pain, especially if the patient is experiencing a relapse.
• Rare Diagnoses
  • Trigeminal Neuralgia: This condition involves sudden, severe, shock-like pain around the eyes, lips, or nose mainly because of abnormal blood vessels pressing on the trigeminal nerve in the head. While the patient's pain is more constant and widespread, some features could overlap.
  • Ehlers-Danlos Syndrome (EDS): This genetic disorder affects the body's connective tissue and could potentially explain some of the patient's symptoms, including joint pain and possibly some neurological features, although it would not directly cause all the symptoms described.

Each of these diagnoses requires careful consideration and further investigation to determine the underlying cause of the patient's symptoms. Given the complexity and the patient's known medical history, a multidisciplinary approach involving neurology, pain management, and possibly other specialties is warranted.