Isolated Lissencephaly Type 1 Without Known Genetic Defect C4275151
A rare brain malformation where folds are absent, causing developmental delays. Managed with supportive therapies and seizure control.
Key facts at a glance
- ICD-10
- G43.909
- ICD-11
- 8A00.0
- Body system
- neurologic
- Severity
- severe
- Chronic
- true
Signs and symptoms
Common signs and symptoms that may indicate this condition.
Warning signs - seek immediate care
Epilepsy
Generalized symptoms
(neurologic)Significant symptoms that substantially affect daily functioning.
Frequency: Common at all stages
Global developmental delay
(neurologic)Hypotonia
(neurologic)Microcephaly
(neurologic)Diagnosis and tests
How this condition is diagnosed and what test results mean.
Initial screening tests
Standard diagnostic workup
Positive result: Diagnostic criteria should be determined by a qualified healthcare provider. [Content pending medical review.]
Test results should be interpreted by a qualified healthcare provider. [Content pending medical review.]
Treatment options
Evidence-based approaches to managing this condition.
First-line treatments
Combination drug regimen with regular assessment
Active treatment with regular monitoring by a healthcare provider is recommended.
Seizure Management
Antiepileptic drug therapy tailored to seizure type and EEG findings in lissencephaly patients. Many patients have refractory epilepsy requiring multiple antiepileptic agents and regular medication adjustments.
Neuroimaging Surveillance
Periodic MRI imaging to monitor for hydrocephalus progression, epilepsy-related changes, and other complications. Helps guide neurosurgical interventions and assess disease progression.
Additional treatment options
Rehabilitative Physical Therapy
Long-term physical therapy focusing on maintaining joint mobility, preventing contractures, and optimizing functional abilities. Addresses the significant motor impairment typical of lissencephaly type 1.
physical_therapyVentriculoperitoneal Shunting
Surgical placement of a CSF shunt to manage hydrocephalus if present, which is common in severe lissencephaly. Requires lifelong monitoring for shunt malfunction and infection.
surgicalComprehensive Developmental Support
Integrative developmental services addressing cognitive impairment, feeding difficulties, and communication challenges. Includes family counseling and transition planning for adult care needs.
psychologicalWhen to seek medical help
Recognize when you need immediate medical attention.
See a doctor within 24 hours
Moderate to severe symptoms that may indicate worsening of this condition. Prompt medical evaluation is recommended.
Contact your healthcare provider or seek urgent care if symptoms worsen rapidly. Go to the emergency department for life-threatening symptoms.
Frequently asked questions
Common questions about this topic.
What is Isolated Lissencephaly Type 1 Without Known Genetic Defect C4275151?
Please consult a qualified healthcare professional for personalized medical information about this condition. [Content pending medical review.]
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Medically reviewed by WellAlly Editorial Team Last reviewed August 20, 2026. · Read our editorial policy