Differential Diagnosis
The patient's symptoms of "wobbling in his knees" and inability to walk in a straight line after restarting gabapentin suggest a range of possible diagnoses. Here are the potential causes, categorized for clarity:
- Single most likely diagnosis
- Gabapentin-induced ataxia: The patient's symptoms started after restarting gabapentin, which is known to cause ataxia (loss of coordination) as a side effect. The temporal relationship between the medication and the symptoms makes this the most likely diagnosis.
- Other Likely diagnoses
- Vestibular dysfunction: The patient's complaint of swaying to one side or the other when walking could be indicative of a vestibular issue, such as benign paroxysmal positional vertigo (BPPV) or labyrinthitis. However, the absence of dizziness or vertigo makes this less likely.
- Proprioception disorder: The patient's inability to walk in a straight line could be related to a proprioception disorder, which affects the sense of body position and movement. This could be due to various causes, including neuropathy or musculoskeletal issues.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Cerebellar stroke or hemorrhage: Although the CT head and CTA head and neck are negative, it is essential to consider the possibility of a cerebellar stroke or hemorrhage, which could present with ataxia and balance disturbances. Further imaging or evaluation may be necessary to rule out this potentially life-threatening condition.
- Multiple sclerosis: While less likely, multiple sclerosis (MS) could present with ataxia, balance disturbances, and neuropathic pain. MS is a potentially debilitating condition that requires prompt diagnosis and treatment.
- Rare diagnoses
- Spinocerebellar ataxia: This is a group of rare genetic disorders that affect the cerebellum and spinal cord, leading to ataxia and balance disturbances. The patient's symptoms could be indicative of a spinocerebellar ataxia, although this would be a rare and unlikely diagnosis.
- Vitamin B12 deficiency: A vitamin B12 deficiency can cause neuropathic pain, ataxia, and balance disturbances. Although less likely, this is a rare diagnosis that should be considered, especially if the patient has a history of malabsorption or dietary deficiencies.